Repro

43 Endometrial cancer

Carcinoma of the uterine endometrium is the most common pelvic malignancy in women. The USA and Canada have the highest incidence rates in the world, whereas developing countries and Japan have inci- dence rates four to ve times lower. Epidemiologic data indicate that there are two forms of endometrial cancer. One is directly related to estrogen exposure and is most common in the USA. The other is unre- lated to estrogen and occurs throughout the world. Estrogen-related type I tumors occur among younger perimenopausal women and carry a good prognosis. In fact, type I lesions are potentially preventable through recognition of patient risk, diagnosis of the precursor lesion (atypical endometrial hyperplasia) and proper treatment. Non-estrogen- related type II tumors occur in older postmenopausal women without a history of estrogen exposure and have a poorer prognosis. The molecu- lar genetic alterations present in type I and II endometrial carcinomas are distinct and may help to explain their clinical characteristics. Cells of the Müllerian tract can differentiate into a wide range of tissue types. This is demonstrated by the variety of histologic subtypes seen among the endometrial cancers. The vast majority are endome- trioid adenocarcinomas. Prognosis for patients with endometrioid adenocarcinoma is determined largely by its degree of differentiation or histologic grade (well, moderately or poorly differentiated). In fact, histologic grade is a prognostic factor independent of stage at diagno- sis. Less common histologic subtypes include mucinous adenocarci- noma, serous adenocarcinoma, clear cell adenocarcinoma, squamous cell carcinoma and a variety of rare mixed and undifferentiated tumors. For all subtypes other than endometrioid adenocarcinoma, prognosis depends more on histologic subtype than on histologic grade. Endometrioid adenocarcinoma rst invades the stroma of the under- lying uterine tissue by destroying the glandular basement membrane. It then invades the myometrium and cervix. Endometrioid adenocar- cinoma typically spreads via the pelvic and periaortic lymphatic chan- nels rather than hematogenously. Vascular invasion is usually seen only with high-grade, non-estrogen-dependent lesions. Treatment of endometrial cancer usually involves surgical removal of the uterus, fallopian tubes and ovaries. Patients with deep myometrial invasion or disease outside of the uterus may be treated postoperatively with radiation, chemotherapy or progestin-based hormonal therapies. Pretreatment analysis of endometrioid adenocarcinoma specimens for estrogen and progesterone receptor status may help to direct postsurgi- cal therapy. There is a good correlation between tumor differentiation and receptor content. Well-differentiated tumors usually have greater numbers of estrogen and progesterone receptors. Because receptor content predicts response to progestin therapy, patients with well- differentiated tumors may be good candidates for progestin therapy. The survival rate for endometrial cancer is relatively good. Overall, survival approaches 70% at both 5 and 10 years. Patients with stage 1 disease, in which the tumor has not invaded through more than half the myometrial thickness, have a 5-year survival rate of over 90%. Because of its high prevalence, endometrial cancer can be considered a neoplasia of high morbidity and relatively low mortality in developed countries. Epidemiology of endometrial cancer Endometrial cancer is largely a disease of the postmenopausal woman. About 80% of cases diagnosed are in women aged 50-75 years of age, with peak incidence in those aged 55-70. A woman entering meno- pause has double the chance of developing endometrial cancer com- pared with her chance for developing carcinoma of the cervix or the ovary. The incidence of endometrial cancer varies dramatically from country to country. This geographic pattern follows that of breast and ovarian cancer, with the highest rates in industrialized countries. It is exactly the opposite of patterns observed for cervical cancer. An association between estrogen exposure and endometrial cancer has been apparent for over 50 years. Many of the risk factors listed in Table 43.1 are thought to increase the risk because of their close association with high estrogen levels, typically unopposed by proges- terone. The single most important and best de ned risk factor for adenocarcinoma of the uterus is obesity. Adipose tissue has active aromatase enzymes. Adrenal androgens are rapidly converted to estro- gens within the adipose tissue of obese individuals. These newly synthesized estrogens also have excellent bioavailability because the metabolic changes associated with obesity inhibit the production of sex hormone-binding globulins by the liver. Obese individuals may have dramatic elevations in their circulating bioavailable estrogens and this exposure can cause hyperplastic growth of the endometrium. Close links exist between the risk of endometrial cancer, a high-fat diet and gross national product, which suggests that level of industrial development may affect incidence of endometrial carcinoma by in u- encing food consumption. A high-fat diet is also associated with obesity and type 2 diabetes mellitus. Amount and type of dietary fat in uences estrogen metabolism. For example, diets rich in beef or in fats increase estrogen reabsorption from the bowel. White women are three times more likely to be diagnosed with endometrial cancer than black women. Again, this is exactly the oppo- site of what is seen for cervical cancer. Steroid hormones and endometrial cancer As noted above, the epidemiologic data on endometrial cancer reveal a striking association between estrogen exposure and cancer development. Interestingly, a direct causal link can only be inferred at this time. The basis for considering estrogen as an etiologic factor comes from three sources: (i) the biologic activity of estrogen and progester- one on the endometrium; (ii) animal and human data on the effects of diethylstilbestrol (DES) on carcinogenesis; and (iii) the association of endometrial cancer with endometrial hyperplasia in conjunction with the association of hyperplasia with prolonged and unopposed estrogen exposure. The strongest attestation to the high sensitivity of the endometrium to ovarian steroid hormones is the dramatic changes that occur in this tissue during each menstrual cycle (Chapters 10 and 14). In a normally cycling woman, the endometrium changes its morphology on a day- to-day basis. In the follicular phase of the cycle, estrogens stimulate proliferation of the epithelium covering the endometrial glands and of the underlying stroma. Estrogen induces production of its own recep- tor and of the progesterone receptor during this time. Progesterone secreted after ovulation promptly arrests the proliferative activity in the glands and converts the epithelium to a secretory state. The stroma responds to progesterone with angiogenesis and functional maturation. If pregnancy should occur, these changes will prepare the endometrium for implantation. It is believed that the potent mitogenic effect of estrogen on the epithelium of the endometrial glands accelerates the spontaneous mutation rate of predisposing oncogenes and/or tumor suppressor genes. This leads to neoplastic transformation. Animal and human data gathered after developmental exposure to DES add biologic evidence for the carcinogenic potential of estrogens in the reproductive tract. DES is a nonsteroidal estrogen agonist that was among the rst synthetic estrogens to be developed. It was admin- istered to over 2 million women between 1940 and 1970 as treatment for threatened miscarriage. In mice, neonatal exposure to DES pro- duces endometrial cancer in 95% of animals by 18 months of age. In women, prenatal DES exposure leads to structural abnormalities of the reproductive tract (Chapter 27) and to clear cell adenocarcinoma of the vagina and cervix. The carcinogenic action of the DES appears to be mediated in part through activation of the estrogen receptor. Whether prenatal DES exposure will cause endometrial cancer in humans will be determined as this cohort of women continues to be followed through menopause. The molecular genetic mechanism by which DES lead to clear cell carcinoma and naturally occurring estro- gens to type I endometrial cancer may be similar. Genetic instability of microsatellite sequences has been demonstrated in both of these tumors. Molecular biology of endometrial cancer K-ras oncogene mutations and microsatellite instability are most common in type I estrogen-related tumors. Mutations of the PT53 tumor suppressor gene and overexpression of the ERBB2 oncogene are more frequently observed in type II non-estrogen-related tumors. Endometrial hyperplasia Endometrial hyperplasia describes a spectrum of changes in the endometrium. These can range from slightly disordered patterns that merely exaggerate the changes seen in the late proliferative stage of the menstrual cycle to irregular, hyperchromatic lesions that are dif- cult to distinguish from endometrioid adenocarcinoma. Nonetheless, noninvasive endometrial hyperplasia can be divided into two basic types: hyperplasia and atypical hyperplasia. Atypia is characterized by nuclear enlargement, hyperchromasia or irregularities in nuclear shape. Hyperplastic lesions can be further subdivided. Simple hyper- plasia describes hyperplastic changes with regular glandular architec- ture while complex hyperplasia has irregular glandular architecture (Fig. 43.1a). Of the four types of endometrial hyperplasias - simple, complex, atypical simple and atypical complex - only atypical complex hyperplasia poses signi cant risk for progression to invasive carcinoma. The progression from hyperplasia is slow and may take 5 years or more. About 20% of women with complex atypical hyperpla- sia will develop endometrial adenocarcinoma (Fig. 43.1b). Only 1-2% of those with the other hyperplastic lesions will progress. Endometrial hyperplasia has the same epidemiologic risk factors as endometrial cancer. Among patients with atypical endometrial hyper- plasia, postmenopausal status is associated with the highest risk of progression to adenocarcinoma (33% over 10 years). Endometrial cancer is rare during the child-bearing years. When it occurs, it is usually associated with clinical disorders that cause chronic, unop- posed estrogen exposure, including the polycystic ovary syndrome and chronic anovulation (Chapter 31). Estrogen-producing ovarian tumors, such as the granulosa-theca cell tumors (Chapter 42), are also associ- ated with the development of endometrial hyperplasia and adenocar- cinoma in premenopausal women. Progesterone-based therapies are used to halt endometrial prolifera- tion and to convert the endometrium to a secretory state in women with endometrial hyperplasia with low malignant potential. Treatment can be given cyclically or continuously. Atypical endometrial hyper- plasia is treated surgically (hysterectomy) unless there is a contrain- dication to the procedure.

Preeclampsia

Clinical spectrum of pre-eclampsia Pre-eclampsia is a unique disorder found only in human pregnancies. Historically, pre-eclampsia has been de ned as the triad of hyper- tension, proteinuria and edema in a pregnant woman. Eclampsia is the occurrence of seizures that cannot be attributed to another cause in a patient with pre-eclampsia. Pre-eclampsia typically occurs in the third trimester of pregnancy, although some cases manifest earlier. Although many patients with pre-eclampsia demonstrate the classic triad, it is now clear that the disorder is really a spectrum of clinical signs and symptoms that accompany microvascular changes in multiple organ systems (Fig. 38.1). The disorder has so many presentations that it has been called the "great imitator." Central nervous system involvement can result in severe headaches, visual changes, seizures, stroke and blindness. Renal involvement is almost always present and can manifest as proteinuria, oliguria or renal failure. Edema can accumulate in many sites, including the feet, hands, face and lungs. Hemoconcentration, thrombocytopenia and intravascular hemolysis are common signs of hematologic involve- ment. Hepatic dysfunction often accompanies hematologic changes and produces a group of clinical ndings known as HELLP syndrome (hemolysis, elevated liver function tests, low platelets). Patients with HELLP will often develop vague epigastric pain resulting from liver involvement which may be mistaken for heartburn, gallbladder disease or the u by an unsuspecting health care provider. The overall incidence of pre-eclampsia in the obstetric population is 5-8%; the absolute number depends on the proportion of patients at increased risk. Risk factors for developing pre-eclampsia include the primigravid state ( rst pregnancy), multiple gestation, diabetes, pre- existing hypertension, a long interval between pregnancies, pre- eclampsia in a previous pregnancy, a family history of pre-eclampsia, hydatidiform mole, and inherited and acquired clotting disorders (e.g., protein S and protein C de ciencies and antiphospholipid antibodies). There is considerable overlap between the risk factors for pre-eclampsia and those for fetal growth restriction (FGR). Indeed, the presence of FGR may be the rst sign of impending pre-eclampsia and women with pre-eclampsia are at risk for delivering a growth-restricted baby. Left untreated, pre-eclampsia can be a highly morbid and even fatal disease. The ultimate treatment for the condition is delivery of the pregnancy. This is so effective a therapy that all deranged physiology will revert to normal after delivery provided that no permanent tissue damage has occurred. If the mother is medically supported through a timely delivery and postpartum recovery, her kidneys will begin to make urine again, blood will clot and seizures will stop. In spite of its potential for a 100% cure with proper diagnosis and treatment, pre- eclampsia remains one of the leading causes of maternal death in both developed and developing countries. Potential mechanisms in pre-eclampsia pathogenesis It is clear that placental abnormalities are central to the pathogenesis of pre-eclampsia. Delivery cures pre-eclampsia and hydatidiform mole, a form of gestational trophoblast disease characterized by pla- cental overgrowth but no fetal development (Chapter 45), predisposes to the disease. It was originally thought that the placenta secreted a toxin that caused pre-eclampsia and the disorder was appropriately called "toxemia." While no unique toxins have been identi ed in the circulation of patients with pre-eclampsia, abnormal concentrations of speci c metabolites are found in many of these patients. Circulating thromboxane, a vasoconstricting prostaglandin, is elevated while nitric oxide production is subnormal. A number of other factors, including a soluble form of a vascular endothelial growth factor (VEGF) recep- tor (sVEGFR-1 or sFlt-1), placental growth factor (PLGF) and soluble endoglin (sENG), a circulating receptor for transforming growth factor β (TGF-β), have been shown to be markedly different in the serum of pregnant women weeks or months before the symptoms of pre- eclampsia manifest. Unfortunately, the test accuracies of these markers are inadequate to predict pre-eclampsia in clinical practice. There are many unproven but enticing theories about the etiology and pathogenesis of pre-eclampsia. It is likely that there are several initiators of the disease that ultimately converge in a nal common pathway. Examination of the small blood vessels in the uteri of women with pre-eclampsia often reveals a failure of the invading trophoblast to remodel the spiral arteries (Fig. 38.2). There are several explana- tions for why the cytotrophoblast might fail to invade these vessels including abnormal immune activation or genetic predisposition. Cytotrophoblast differentiation into an invasive phenotype is accom- panied by increased production of VEGF and PLGF, both proang- iogenic factors. Placentas from pre-eclamptic pregnancies secrete increased amounts of sFlt-1, the soluble antagonist to VEGF, and sENG; both are antiangiogenic factors. Abnormal immune activation that inhibits trophoblast invasion of maternal blood vessels could explain why pre-eclampsia is most common when a woman is exposed to paternal antigens for the rst time: a rst pregnancy or, in a multigravid woman, the initial preg- nancy with a new partner. Loss of immune tolerance over time would also explain why a long interval between pregnancies is a risk factor for developing pre-eclampsia. Abnormal activation of the immune system underlies other autoimmune diseases, such as systemic lupus erythematosus, that carry an increased risk for pre-eclampsia. Some women with pre-eclampsia have activating autoantibodies to the angi- otensin II receptor that inhibit trophoblast invasiveness in vitro. Speci c genetic abnormalities may be involved in the pathophysiol- ogy of pre-eclampsia. Women who carry a mutation in the complement receptor CR-1 have an increased risk for pre-eclampsia as do women carrying a speci c polymorphism for plasminogen activator inhibitor type 1. Pre-existing insulin resistance confers an increased risk. The fact that a family history of pre-eclampsia increases a woman's risk for the disease indicates that there may be many additional genetic predispositions to the disease. A mismatch between fetal and placental demands and the maternal ability to meet them may also cause pre-eclampsia and would explain risk factors such as multiple gestation, maternal vascular disease and hypercoagulable states. Proponents of this theory propose that the undernourished fetus sends signals to the mother to increase perfusion of the placenta. If the mother cannot compensate in response to these initial signals, the fetus sends more urgent signals. Pre-eclampsia would theoretically result from the effects of excessive signals. As an example, hypoxia has been shown to increase the production of sFlt-1 by tro- phoblast cells. Increased sFlt-1 may be part of the pathogenesis of pre-eclampsia. While the initiating placental abnormality is unclear, the nal common pathway for pre-eclampsia is known to be endothelial dys- function and injury. The vascular endothelium normally functions to prevent microcoagulation and to modulate vascular tone. Vascular injury results in coagulation and alters the response of the underlying vascular smooth muscle to vasoactive substances. Often, substances that act as vasodilators on an intact endothelium will cause vasocon- striction of damaged endothelium. In pre-eclampsia, endothelial dys- function can solely explain the basic triad: hypertension (vasospasm), edema (capillary leak) and proteinuria (renal cell damage secondary to hypoperfusion). Experiments in animal models indicate that excess sFlt-1 can directly produce some of the organ dysfunction seen in pre-eclampsia. What remains inexplicable is why only a few, but not all, of the signs and symptoms of pre-eclampsia will appear in any given patient.

. Ch 14: The menstrual cycle

Gametogenesis and steroidogenesis proceed in a continuous fashion in the postpubertal human male. In contrast, the postpubertal human female exhibits repetitive cyclic changes in the hypothalamic-pituitary-ovarian axis that allow: (i) the maturation and release of gametes from the ovary; and (ii) the development of a uterine environment prepared to support a pregnancy should fertilization occur. In the absence of conception, each cycle ends in menstrual bleeding. The pituitary gonadotropins, luteiniz- ing hormone (LH) and follicle-stimulating hormone (FSH), link the hypothalamus and the ovary and mediate these cyclic changes. The menstrual cycle is best understood if divided into the four phases of functional and morphologic changes in the ovary and endometrium: (i) follicular, (ii) ovulatory, (iii) luteal and (iv) men- strual (Fig. 14.1). Follicular phase Conventionally considered the rst phase, this is the phase of the menstrual cycle leading up to ovulation. In a typical 28-day menstrual cycle, it comprises the rst 14 days. In ovulatory cycles of more or less than 28 days' duration, the deviation from the average is largely caused by differences in the length of the follicular phase. During this phase of the menstrual cycle, a cohort of ovarian follicles will rapidly mature, although only one typically becomes the dominant follicle, called the Graa an follicle. Those follicles that undergo nal maturation in a given cycle have likely been growing for several months prior to that cycle. Progression from the primordial or resting state to the small antral stage is largely gonadotropin-independent. During the few days prior to the start of menstruation, a small cohort of these growing follicles, now at the small antral stage, is recruited for further gonadotropin-dependent growth. As one cycle ends, the scheduled demise of the corpus luteum results in a rapid decline in its hormonal secretion. The resultant fall in serum estradiol releases the central nega- tive feedback inhibition on FSH secretion. Associated declines in pro- gesterone and inhibin A are involved to a lesser degree. Increases in FSH secretion during the late luteal phase are accompanied by an increase in the pulse frequency of LH secretion. Day 1 of menstrual bleeding is considered the rst day of the follicu- lar phase. During days 4-5 of this phase, development of the recruited ovarian follicle cohort is characterized by FSH-induced granulosa cell proliferation and aromatase activity. The theca cells of the developing follicle produce androgen precursors. These are converted into estradiol within neighboring granulosa cells. The process has been called the two-cell hypothesis (Chapter 2). Estradiol levels increase. The recruited follicles have several layers of granulosa cells surrounding their oocytes and a small accumulation of follicular uid. FSH induces synthesis of additional FSH receptors on granulosa cells, expanding its own effects. FSH also stimulates synthesis of new LH receptors on the granulosa cells, thereby initiating LH responsiveness. By days 5-7 of the menstrual cycle, a single, selected follicle pre- dominates to the detriment of the others in the selected cohort, and will mature and ovulate between days 13 and 15. The predominant follicle is characterized by the highest mitotic index of all the recruited follicles, an optimal capacity for FSH retention in its follicular uid, and high estradiol and inhibin B synthesis. Nondominant follicles have elevated androgen : estrogen ratios in their follicular uid, suggesting suboptimal induction of aromatase activity, and will undergo atresia. Androgens appear to be key to the atresia process, as granulosa cells treated with androgen in vitro undergo apoptosis. During the mid to late follicular phase, continued elevations in circulating estradiol and inhibin B suppress FSH secretion, so prevent- ing new follicular recruitment. Continuous high elevations of circulat- ing estradiol exert a somewhat unexpected effect on the pituitary gland; exponential increases in LH secretion. The ovary also exhibits increased responsiveness to the gonadotropins. Lastly, high estrogen levels cause growth of the endometrial tissue lining the uterus. These changes in the endometrium can be distinguished microscopically and are de ned as the "proliferative phase" (Chapter 10). Ovulatory phase This phase of the menstrual cycle is characterized by a surge in pitui- tary LH secretion, culminating in extrusion of the mature ovum through the capsule of the ovary. In the 2-3 days preceding the onset of the LH surge, circulating estradiol and inhibin B rise rapidly and in parallel. Estradiol synthesis is at a maximum and no longer depend- ent on FSH. Progesterone begins to rise as the surging LH induces progesterone synthesis by the granulosa cells. Key to ovulation is the midcycle positive feedback effect of estro- gen on LH secretion. Proof that rising ovarian estrogens are central to ovulation lies in the observation that a gonadotropin surge can be elicited when prolonged elevated circulating estradiol concentrations are produced experimentally by 2-3 days of exogenous estrogen administration in women. The effects of elevated circulating estrogen are further augmented by the presence of ovarian progesterone. The site of the positive feedback actions of midcycle estrogen on LH secre- tion appears to be in both the hypothalamic neuroendocrine cells and the pituitary gonadotropes. The exact mechanism by which estrogen induces the midcycle LH surge is uncertain, but dopaminergic and β-endorphinergic neuronal modulation of the gonadotropin-releasing hormone (GnRH) pulse generator are involved. In fact, at midcycle, there is a 20-fold increase in sensitivity of the pituitary gonadotropes to GnRH. Further, the GnRH pulse generator can be inhibited by both synthetic and naturally occurring opioids, suggesting that opioids have a pivotal role in the neuronal control of the midcycle LH surge. A small rise in FSH occurs simultaneously with the pronounced rise in LH at midcycle, presumably in response to the GnRH signal. Ovulation appears to require LH. The exact mechanism of this effect is unknown, although prostaglandins are thought to be at least one of the mediators. To this point, LH has been shown to stimulate prostag- landin biosynthesis by ovarian cells and inhibitors of prostaglandin synthesis inhibit ovulation in animals. Luteal phase After ovulation, the dominant morphologic and functional feature of the ovary is the formation and maintenance of the corpus luteum. In humans, the luteal cells make large amounts of estrogen and inhibin. In fact, the circulating estrogen concentrations during the luteal phase are in the preovulatory, positive feedback range. Characteristic of the luteal phase, however, are the uniquely high concentrations of proges- terone and 17-hydroxyprogestrone secreted by the corpus luteum. Progesterone at these elevated levels prevents estrogen from stimulat- ing another LH surge from the pituitary. Instead, in the presence of the combination of high concentrations of progesterone and estrogen, the preovulatory GnRH pulses are reduced in frequency, resulting in only baseline FSH and LH secretion. The length of the luteal phase is more consistent than that of the fol- licular phase, normally 14 ± 2 days. If pregnancy does not ensue, the corpus luteum spontaneously regresses and follicular development proceeds for the next cycle. Only small amounts of LH are necessary to maintain the corpus luteum in a normal cycle. However, after 14 days, even basal LH secretion will not support the endocrine function of the gland. If pregnancy ensues, maintenance of the corpus luteum and progesterone production is critical to the success of the early gestation. Human chorionic gonadotropin (hCG) is a hormone homologous to LH. hCG is secreted by the placental tissues (trophoblast) of a developing pregnancy. Therefore, in the presence of pregnancy, hCG secreted by gestational trophoblast can maintain the corpus luteum until the tro- phoblast assumes the role of progesterone secretion (Chapter 18). High progesterone levels also create the "secretory phase" of the endometrium, which is marked by endometrial maturation that can allow implantation of the embryo (Chapter 16). The exact trigger for the demise of the corpus luteum in a cycle that does not result in pregnancy is unknown. DNA fragmentation patterns characteristic of apoptosis appear in the corpus luteum as early as the mid to late luteal phase. The rise in FSH secretion near the end of the luteal phase is reliant on a concomitant drop in the high circulating levels of proges- terone, estradiol and inhibin. It is clinically signi cant that an estrogen antagonist such as clomiphene citrate, administered in the luteal phase, causes a rise in circulating FSH levels and initiation of follicular recruitment. Menstrual phase The rst day of menstruation marks the beginning of the next cycle. A new wave of follicles has been recruited and will progress toward maturation and, for one, ovulation. The phenomenon known as men- struation is largely an endometrial event, triggered by the loss of progesterone support from the corpus luteum in nonconception cycles. Dramatic structural changes occur in the endometrium during men- struation, driven by complex and only partially understood mecha- nisms. Hormonally regulated matrix-degrading proteases and lysosomes appear to be involved. Matrix-degrading proteases are part of the metalloproteinase (MMP) family of enzymes whose substrates include collagen and other matrix proteins. Of the MMP family, seven members are expressed in cell- and menstrual cycle-speci c patterns. Also, the endothelins, which are potent vasoconstrictors, appear to have maximum activity at the end of the luteal phase. Finally, the premenstrual fall in progesterone is associated with a decline in 15-hydroxyprostaglandin dehydrogenase activity. This results in an increase in the availability of prostaglandin PGF2α, a potent stimulator of myometrial contractility. Prostaglandin and thromboxane homeos- tasis direct myometrial and vascular contractions within the uterus. Control of such contractility is central to the creation of endometrial ischemia, the promotion of endometrial sloughing and the cessation of menstrual bleeding.

multifetal pregnancy

A pregnancy in which the woman is carrying two or more fetuses. Also called multiple gestation. Etiology of dizygotic twins Most of the spontaneously conceived multifetal pregnancies are twin gestations. The incidence of conception of twins is at least twice the rate of liveborn twins. In many cases, one of a pair of diamniotic dichorionic twins just disappears. Less often, the whole pregnancy miscarries. The frequency of monozygotic twinning is about 1 set in every 250 births and is relatively xed in most populations. In contrast to monozygotic twinning, the incidence of dizygotic twinning varies dramatically among different populations. Dizygotic twinning is highly in uenced by race and heredity. Maternal age over 40, increas- ing parity and infertility treatment are positively linked to dizygotic twinning. The racial differences in dizygotic twinning are quite marked. Twin- ning among Asians is least common, with a rate of only 1.3 dizygotic twin births per 1000 total births in Japan. White women in the USA and the UK have rates of about 8 dizygotic twin sets per 1000 births. Black women have the highest rates of all. They range from a rate of 11 per 1000 births in the USA to 49 per 1000 in some tribes in Nigeria, or 1 in every 20 births. The in uence of heredity on dizygotic twinning is carried largely through maternal lineages, with about a 2% chance of delivering twins if the mother herself is a dizygotic twin. When the father of the baby is a dizygotic twin, the rate of twinning is only 0.8%. In developed countries, most multifetal pregnancies result from infertility treatments. Ovulation induction, in vitro fertilization (IVF) and other assisted reproductive techniques dramatically increase the frequency not only of twinning, but also of conceiving higher order multiple gestations (triplets, quadruplets and more); (Fig. 35.2). Table 35.1 lists recent outcome data approximating the frequency of multi- fetal pregnancies in the USA, dependent on the means of conception. If one uses Hellin's theorem to calculate the expected frequency of twins in Nigeria, which has the highest spontaneous twinning rate in the world, one can see the impact of infertility treatment on the higher- order multiple gestations. Hellin's theorem states that if the frequency of twinning is n in a population, then the frequency of triplets is n2, quadruplets n3, and so on. Using n = 0.05 for the Nigerian tribes, one would only expect 0.25% triplet and 0.012% quadruplet gestations. Thus, infertility treatment can increase the risk of triplets 20-fold and quadruplets 80-fold over the world's most "twinningest" people. Although infertility treatment dramatically increases the frequency of nonidentical multiples, the rate of monozygous twinning is also double that expected in these women. A disproportionate number of these monozygotic twins are also monochorionic. Transfer of day 5 blastocysts into the uterus during IVF is associated with a higher rate of monozygotic twins than transfer of day 3 zygotes. The stimuli for monozygotic twinning following ovulation induction alone have not been identi ed. Elevated gonadotropins promote recruitment of more than one ovarian follicle in a given cycle and represent the single most important risk factor for dizygotic conceptions. This is most evident during infertility treatments where the use of injected gonadotropins is associated with the development of multiple ovulatory follicles. The increased rates of spontaneous twinning seen with black race, advanc- ing maternal age, parity and heredity are also related to elevations in endogenous gonadotropins, most notably in FSH. Pregnancy risks with multiple gestations The inherent risk in multiple gestations depends largely on whether single or multiple placentas are present and on whether there is a shared amniotic sac. All monochorionic twins have some degree of vascular connection within the placental bed. In about 15% of mono- chorionic twin pregnancies, these vascular connections permit the exchange of blood between the two fetuses. When this occurs, the hemodynamics of the two twins can become so deranged that one fetus will preferentially pump extra blood into the other ("twin-twin trans- fusion syndrome"). The "donor" twin becomes anemic and produces an abnormally low amount of amniotic uid, whereas the "recipient" twin is volume overloaded and produces excessive amounts of amni- otic uid. Fetuses in multiple gestations also have an increased risk for abnormal insertion of the umbilical cord onto the placenta. The umbilical cord typically inserts into the middle of the placental disc and is completely surrounded by a protective layer of Warton's jelly. With multiple gestations, each fetus has an increased incidence of having its cord insert along the edge of the placenta (velamentous insertion). Cords with velamentous insertions are not completely sur- rounded by Warton's jelly and can be kinked or compressed more readily than more protected cords. Such compression can result in suboptimal fetal blood ow. The umbilical cords of monoamniotic twins invariably become entangled. This leads to fetal deaths in over half of the cases. In addition to the problems that can arise from their placentas and membranes, monozygotic twins are also at increased risk of chromo- somal abnormalities and congenital malformations. Because affected twin pairs are often discordant for the abnormality, it is presumed that whatever intrauterine events caused these embryos to divide can also randomly increase the risk for disordered embryonic development. All multiple gestations are at risk for growth restriction of one or more of the fetuses. The risk increases as the number of fetuses increases. There are many possible causes for fetal growth restriction in multiple gestations. Suboptimal perfusion of the area of placental implantation of one or more fetus can cause fetal growth restriction. Velamentous umbilical cord insertions may also cause decreased fetal perfusion and growth restriction, as can donation of blood to a co-twin in the twin-twin transfusion syndrome. All multiple gestations are at risk for preterm labor (Chapter 37). The risk increases in parallel with increasing numbers of fetuses. Uterine distension may explain the early onset of labor in pregnancies complicated by multiple gestations; however, other nonmechanical factors may also be involved.

Ch 26: Abnormalities of male sexual differentiation and development

Cryptorchidism An undescended testis (cryptorchidism) is the most common genital abnormality seen in male newborn infants. It occurs in 3% of babies. Either one or both testes may be involved. Cryptorchidism occurs when the gubernaculum fails to develop or fails to pull the testes into the scrotum. Androgen activity directs gubernacular development and function, thus gubernacular dysfunction re ects androgen abnormali- ties. Insuf cient androgen activity can result from developmental defects anywhere along the fetal hypothalamic-pituitary-testicular axis. To this point, cryptorchidism can result from any of the following: (i) fetal hypothalamic failure to stimulate gonadotropin secretion in the third trimester (Kallmann and Prader-Willi syndromes, anencephaly); (ii) failure of the testes to secrete androgens (gonadal dysgenesis); (iii) failure of testosterone conversion to dihydrotestosterone (DHT) in target tissues (5α-reductase de ciency); or (iv) absence of functioning androgen receptors (androgen insensitivity syndromes) (Table 26.1). Cryptorchid testes may remain in the inguinal canal (70%), the abdomen or retroperitoneum (25%), or other ectopic locations (5%). Testes remaining in the abdomen or inguinal canal will be exposed to comparatively higher temperatures than those in the scrotum and will cease spermatogenesis in response. They are also prone to neo- plastic change. Medical therapy for cryptorchidism involves adminis- tration of human chorionic gonadotropin (hCG) or androgens. Surgical therapy is called orchiopexy. Some cryptorchid testes are unresponsive to medications or cannot be brought into the scrotum surgically. These testes are usually removed because they cannot be adequately moni- tored for the development of a neoplasm. Inguinal hernia is a forme fruste of cryptorchidism. Here, testicular descent occurs, but the inguinal ring does not close completely after descent. Boys who have an inguinal hernia diagnosed before the age of 15 have twice the risk of developing testicular cancer when com- pared to boys in the general population. Hypospadias Hypospadias is a very common congenital abnormality seen in male newborn infants. In hypospadias, the urethral meatus opens on to the ventral surface of the penile shaft at sites proximal to the normal loca- tion (Fig. 26.1). Embryologically, hypospadias results from a failure of complete ventral closure of the urethral groove. The penile urethra depends on the androgen DHT to differentiate. Therefore, hypospadias can result from de ciencies in testosterone (T) production, from inad- equate conversion of T to DHT, or from local de ciencies in androgen recognition (insuf cient androgen receptor number or function). There is a non-Mendelian genetic predisposition to hypospadias. If one sibling has a hypospadias, the recurrence risk is 12% in that family. If both the father and a brother are affected, the risk for a second son is 25%. Cryptorchidism is seen in 16% of boys with hypospadias. If both are present, the child may be a pseudohermaphrodite and chromo- somal and hormonal testing should be obtained. Congenital bilateral absence of the vas deferens Congenital bilateral absence of the vas deferens (CBAVD) is a rare congenital anomaly found most often in men with cystic brosis (CF). It can also occur in the absence of clinically apparent CF. When it does, it is usually associated with mutations in the gene coding for the CF transmembrane receptor (CFTR). The molecular mechanism by which an abnormal transmembrane receptor involved in chloride channels leads either to failure of the vas deferens to differentiate or to its resorption is not known. The presence of CBAVD mandates genetic testing for CF genes. Microorchidism The presence of at least one additional X chromosome in most of the cells of a man with Kleinfelter syndrome (usually 47XXY) results in hypogonadism and frequent infertility and microorchidism. XXY men are variably affected with other physical (tall stature, gynecomastia) and behavioral (speech and learning) problems. This is the most common sex chromosome aneuploidy in males and may be one of the most common chromosome abnormalities in humans. Pseudohermaphroditism Individuals possessing testes, but in the presence of external and/or internal genitalia with a female phenotype are called male pseudoher- maphrodites. Gonadal sex does not match genital phenotype. Male pseudohermaphroditism results from an inappropriate fetal hormonal environment. This can be caused by biochemical defects in androgen activity or by abnormal sex chromosome constitution. Pseudoher- maphroditism is a rare disorder, but its multiple etiologies have offered the opportunity to further understand the role of steroids in human genital development. A list of the known biochemical defects leading to male pseudohermaphroditism includes: • Androgen insensitivity syndromes • 5α-reductase de ciency • Testosterone biosynthesis defects • Congenital adrenal hyperplasia (CAH) syndromes • Impaired androgenization • Anti-Müllerian hormone defect. Androgen insensitivity syndromes The androgen insensitivity syndromes are a group of X-linked reces- sive traits that produce a spectrum of incompletely virilized pheno- types. The most severe form, complete androgen insensitivity (AI), was originally known as testicular feminization. In complete AI, the intracellular androgen receptor is absent or nonfunctional. Androgen induction of Wolf an duct development does not occur. Müllerian- inhibiting substance (MIS) is produced by the normally functioning testes and the Müllerian ducts regress. The testes descend to the level of the inguinal ring under the in uence of MIS. A short vagina forms from the urogenital sinus. At birth, children with complete AI are typically assigned the female sex because there is no trace of androgen activity and the external genitalia clearly appear female. Complete AI is typically diagnosed after puberty when primary amenorrhea becomes apparent. Examination of the complete AI individual reveals a blind- ending, short vagina and an absent cervix, uterus and ovaries. Breast development is normal, but axillary and pubic hair is scant or absent. Complete AI accounts for about 10% of all cases of primary amenor- rhea. In contrast to those individuals with a dysgenetic gonad bearing a Y chromosome, those with complete AI have less than a 5% risk of developing a gonadal tumor. Gonadal tumors that do develop in AI patients rarely appear before age 25. Therefore, gonadectomy is post- poned until puberty is complete. The incomplete androgen insensitivity syndrome (Reifenstein syndrome) is far less common than the complete and is associated with a broad spectrum of phenotypes. These vary from almost com- plete failure of internal and external genital virilization to complete phenotypic masculinization. Between these extremes exist patients with mild clitoromegaly and slight labial fusion to those with signi - cant genital ambiguity. Recently, several men have been described whose only indication of AI was infertility resulting from low or absent sperm production. Some fertile males who appear underviri- lized probably have a mild form of this disorder. Incomplete AI results from mutations in the androgen receptor gene. The gene encoding the androgen receptor localizes to the q11-12 region of the X chromosome. Defects can occur in the androgen- binding domain of the receptor, the DNA-binding domain of the recep- tor or in receptor protein production. Identi ed abnormalities range from complete loss of receptor function to subtle qualitative changes in the transcription of androgen-dependent target genes. There is poor correlation between absolute androgen receptor levels and the degree of masculinization seen in patients with incomplete AI. 5α-reductase de ciency The syndrome seen among patients with 5α-reductase de ciency was originally given the name pseudovaginal perineoscrotal hypospadias (PPH). It differs from AI in that masculinization occurs at puberty. At birth, individuals with 5α-reductase de ciency have external genitalia that resemble those of incomplete AI, including hypospadias, varying degrees of failure of the labioscrotal folds to fuse and either a urogenital opening or separate vaginal and urethral openings. The cleft in the scrotum resembles a vagina and most children with 5α-reductase de - ciency are raised as girls. In these patients, adrenal steroid production is normal and the karyotype is XY. Measuring blood levels of testoster- one and DHT and demonstrating an elevated T : DHT ratio can establish the diagnosis of 5α-reductase de ciency and eliminate the diagnosis of CAH in an incompletely virilized newborn infant (Chapter 27). Molecular analyses have demonstrated that there are two 5α-reductase genes; mutations in the isoenzyme coded on chromo- some 2 (SRD5A2 gene) are responsible for this form of male pseudo- hermaphroditism. Multiple mutations of SRD5A2 have been identi ed. The segregation of the same speci c defects in unrelated individuals of the same ethnicity suggests common ancestry. Compound hetero- zygotes are common, suggesting that the gene frequency for SRD5A2 mutations may be fairly high. Women are not clinically affected by 5α-reductase de ciency. Congenital adrenal hyperplasia syndromes A group of enzymatic defects of the steroidogenic pathways cause reproductive and metabolic disorders collectively known as the CAH syndromes. Among these, lipoid congenital adrenal hyperplasia (StAR protein de ciency), 3β-hydroxysteroid dehydrogenase de - ciency, 17α-hydroxylase de ciency and 17β-hydroxysteroid dehy- drogenase de ciency can cause feminization of fetal external genitalia. All are speci c enzymatic defects in the steroidogenic pathway common to the testes and adrenal glands and all involve enzymes occurring early in the steroidogenic pathway between cholesterol and testosterone (Chapters 2 and 29). CAH syndromes that cause mascu- linization in female fetuses are much more common and result from enzymatic defects more distal in the steroidogenic pathways. Gender assignment Gender assignment in male infants with pseudohermaphroditism requires knowledge of the speci c defect. Most are raised as females. Individuals with complete AI (testicular feminization) are raised as females because they unambiguously appear as females at birth. In addition, because they lack functional androgen receptors, AI patients will never be virilized. Males whose incomplete AI presents with ambiguous genitalia are also usually raised as females because predict- able feminization with gynecomastia will occur at puberty. Males with 5α-reductase de ciency have been successfully raised as either females or males. In fact, in cultures with a high frequency of the disorder, children have been raised as females in childhood and males after puberty. Patients with 5α-reductase de ciency who are assigned as females and wish to retain their female gender will need to be gonadec- tomized to avoid deepening of their voices and a male pattern of muscle development that will occur at puberty. Both will occur in response to pubertal testosterone, a substance to which they can respond. Estrogen and progesterone therapy can be used to produce female secondary sexual development. Patients with 5α-reductase de ciency who are assigned to the male gender require repair of their hypospadias and cryptorchidism. At puberty, spermatogenesis and masculine sexual maturation will occur under the in uence of testosterone. True gonadal dysgenesis is relatively rare in individuals with an XY karyotype. Bilateral dysgenesis of the testes (Swyer syndrome) results in normal, but infantile female external and internal genital develop- ment and lack of secondary sexual development at puberty. Fibrous bands appear in place of the testes. Gonadectomy is necessary to prevent the 20-30% risk of tumor formation. Estrogen and progesterone therapy support female secondary sexual development at puberty.

45 Genetic imprinting and reproductive tract tumors

Imprinting Imprinting is the differential expression of a gene or set of genes that is determined by whether that genetic material was inherited from the mother or from the father. During the imprinting process, speci c genes are methylated so that they can no longer be transcribed. Therefore, for certain genetic loci, only the information from one parent is transcrip- tionally active. When a gene is maternally imprinted, the gene acquired from the mother is inactive and that from the father is transcribed. With paternal imprinting, the allele acquired from the father is inactive. Normal embryonic development requires that one set of genes be maternally imprinted and a second paternally imprinted. Therefore, a zygote must not only have a 2n chromosome content but each of the 1n components must derive from different parents. Several tumors of the reproductive system have helped us to better understand the process of imprinting and the consequences of imprinting abnormalities. Gestational trophoblastic disease (GTD), dermoid cysts of the ovary and germ-cell tumors (GCTs) of the testis all display abnormalities in imprinting. GTD and dermoid tumors contain two sets of chromo- somes from a single parent, so there exists no opportunity for bipa- rental imprinting. Two sets of maternally imprinted genes are present in dermoid tumors of the ovary. The result is development of disorgan- ized fetal tissues without any supporting placenta or fetal membranes. Conversely, two sets of paternally imprinted genes are present in GTD. In these cases, dysplastic trophoblast develops, but a fetus does not. GCTs of the testis have taught different lessons concerning the impor- tance of imprinting. GCTs that arise in immature and incompletely imprinted cells are more aggressive than those that arise in fully imprinted germ cells. Gestational trophoblastic disease GTD is one of the earliest reported neoplasms. Hippocrates rst described "dropsy" of the uterus in 400 bc and a 13th century tomb- stone noted the birth of 365 "children," half boys and half girls, to the woman buried there. Today GTD, also called molar pregnancy, retains its leading position in tumor biology as the most sensitive and curable of all human cancers. The genetic origin of molar pregnancies has also played a pivotal part in our understanding of the role of the maternal and paternal genome in embryonic development. There is a spectrum of diseases within the GTD classi cation: hydatidiform mole, either complete (CHM) or partial (PHM), persist- ent, nonmetastatic GTD, metastatic good-prognosis GTD and meta- static poor-prognosis GTD. The latter includes aggressive tumors known as choriocarcinomas (CC). Of these, CHM and PHM follow abnormal conceptions and are restricted to women. CC is unique among GTD in that it can arise from a normal conception, a molar pregnancy or a germ-cell line. CC in men is exclusively of germ-cell origin (Chapter 40). CHM and PHM contain two sets of paternal chromosomes (Fig. 45.1). The former has only paternally derived genomic DNA. This situation promotes the development of placental tissues in the absence of fetal tissue development. In PHM, two sets of paternal chromo- somes are accompanied by a single set of maternal chromosomes. Again, the paternally imprinted genes are duplicated and placental overgrowth occurs. Here, maternally imprinted genes are also present and fetal tissue development is seen. Complete hydatidiform mole CHM is the most common of the GTDs and occurs in about 1 in 1000-1500 pregnancies in Western countries. It is at least twice as common in Asia but less common in black races. Extremes of age increase the risk for CHM, with women under 15 and over 40 at highest risk. Other risk factors include previous history of CHM, previous miscarriage, maternal balanced chromosomal translocation, profes- sional occupation and perhaps de ciencies in animal fat and carotene in the diet. A previously normal pregnancy lowers the risk of CHM. CHM is characterized histologically by the presence of large amounts of hydropic placental villi and no fetal tissue. It presents clinically with delayed menses and the diagnosis of pregnancy. Pregnancy symptoms such as nausea and vomiting are often exaggerated because of the high human chorionic gonadotropin (hCG) production by the abnormal trophoblast. Some patients with CHM will be hyperthyroid because hCG exhibits some intrinsic thyroid-stimulating activity. Women with CHM who want to preserve their fertility are treated by removing the molar tissue from the uterine cavity (uterine evacuation). Those who do not desire future fertility may choose hysterectomy. Eighty per cent of CHMs will respond to these approaches. Those who ave persistent disease require chemotherapy and the vast majority will ultimately be cured. CHM is exquisitely sensitive to antimetabolite chemotherapy, typically methotrexate with folate rescue. The unique genetic origins of CHM were suspected well before the advent of modern molecular techniques when karyotype analyses revealed that 96% of them were 46XX. Polymerase chain reaction and restriction fragment length polymorphism (RFLP) analyses have dem- onstrated that while CHM is always diploid, the chromosomes are all of paternal origin. Most CHMs arise from fertilization of an enucle- ate, or empty egg, with a single 23X sperm. This paternal haplotype reduplicates and the 46XX karyotype results. The remaining CHMs arise after fertilization of the enucleate egg with two sperm (dispermy); of these about one-quarter (4% of the total CHMs) will have a 46XY karyotype. All CHM have maternal mitochondrial DNA and this con- rms that the oocyte cell machinery is involved. To date, the mechanism by which the egg enucleates is not known. Some hypothesize that the maternal chromosomes degenerate, others pose that the female pronu- cleus is extruded with the polar body (Chapters 4 and 16). Partial hydatidiform mole PHM exists when proliferative villi with hydropic degeneration coexist with a fetus. The fetus is genetically abnormal and will com- monly die by the late rst or early second trimester. The villous hydropic changes seen in PHM are not as pronounced as those in CHM and may be missed on ultrasonographic examination. Pathologic examination of the placenta is often necessary to make the diagnosis. Patients with PHM tend to be older than those with CHM. PHM has a lower risk of subsequent malignancy than does CHM. PHM pregnancies are all triploid and contain two copies of the paternal genome. PHM pregnancies most commonly arise from dis- permic fertilization (diandry). They occasionally occur after fertiliza- tion by a diploid sperm that failed to undergo a rst or second reduction division during meiosis (Chapter 4). Persistent and metastatic gestational trophoblastic disease Persistent and metastatic GTD are typically preceded by CHM. They occasionally follow PHM or even normal pregnancies. Persistent GTD can invade the uterus or metastasize to liver, lung and brain. Even meta- static disease has a very high cure rate with appropriate treatment. Genetic study of neoplastic trophoblastic tissue is very important to the patient because gestational tumors have a better than 90% cure rate whereas nongestational tumors with trophoblastic differentiation are essentially lethal. Dermoid tumors Benign ovarian teratomas, also known as dermoids, arise from "par- thenogenetic" activation of premeiotic oocytes. Parthenogenetic acti- vation of the oocyte stimulates oocyte mitosis in the absence of the male pronucleus and its accompanying DNA. Parthenogenetic activa- tion can be induced in vitro by a variety of methods, including chemi- cal and electrical exposure. The stimuli that drive parthenogenesis in the formation of ovarian teratomas are not known. All the chromo- somes in an ovarian dermoid tumor are maternally derived and, there- fore, maternally imprinted. The tumors are characterized by disorganized overgrowth of many of the cell types normally seen in fetuses. This includes hair, bone, cartilage, adipose tissue and glandu- lar derivatives (Fig. 45.2). Ovarian dermoid tumors arise from more mature germ cells than the other female GCTs (Chapter 42). Like other GCTs, the molecular event(s) that lead to activation of the germ cells can occur in utero, and indeed dermoid tumors have been detected in the fetus and newborn infant. GCTs of the testis Spermatocytic seminomas are unique among the GCTs of the testis in that they are found in older men and are typically slow-growing (Chapter 40). This less aggressive behavior may occur because sper- matocytic seminomas arise from mature spermatogonia rather than spermatogonial stem cells. During the development of spermatozoa, the diploid (biparental) spermatogonial stem cell must undergo reduc- tion division to the haploid state. It is equally important that the DNA in these haploid cells be completely uniparental. If this occurs, appro- priate paternally imprinted DNA will be transmitted during fertiliza- tion. Imprinting appears to occur during spermatocyte maturation some time after the second meiotic division halves the chromosome number. When neoplastic transformation occurs in immature testicular germ cells, the biparental imprinting of the cells preserves pluripoten- tiality and allows the development of less differentiated, aggressive tumors with embryonal or trophoblastic components. When transfor- mation occurs in more mature and fully imprinted spermatogonium, the tumors are less aggressive (spermatocytic seminomas).

Menopause

Menopause is a normal stage of life. Its health consequences have only become apparent as life expectancy has increased well beyond the 6th decade of life for women. It is estimated that women living in developed countries will live at least one-third of their lives after menopause. Functionally, menopause may be considered an "estrogen withdrawal syndrome." It is recognizable by the loss of menses and, for most women, by the appearance of signs and symptoms such as hot ashes, insomnia, vaginal atrophy, decreased breast size and reduced skin elasticity. Osteoporosis and cardiovascular disease rep- resent longer term consequences of estrogen de ciency (Fig. 24.1). Both are more indolent and less predictable than the early signs and symptoms of menopause. Physiology of menopause The postmenopausal ovary is small and essentially devoid of follicles. The appearance of the postmenopausal ovary, coupled with the obser- vation that oophorectomy is associated with menopausal symptoms, led to the original theory that follicular depletion was responsible for menopause. More recent evidence suggests that menopause has origins in both the central nervous system and the ovary. In addition, men appear to experience a similar, albeit later and more subtle change, called andropause. Both changes can be referred to as "gonadopause" and associated mechanisms in the central nervous system and gonads seem to be quite extensive and to re ect the general aging process. Fertility decreases dramatically in women beginning at about age 35 but accelerating after the age of 40. The accelerated fall after 40 may be the rst sign of impending ovarian failure. Although ovarian follicles remain visible on ultrasound, attempts at arti cial induction of ovulation with injected gonadotropins are largely unsuccessful after about age 45 years. This suggests that a physiologic defect develops within the oocytes or follicles prior to their depletion. About 3-4 years before menopause is apparent, serum follicle-stimulating hormone (FSH) levels begin to rise subtly and ovarian estrogen, anti-Müllerian hormone, inhibin and progesterone production falls. Menstrual cycle length tends to decrease as the follicular phase progressively shortens. Ultimately, ovulation and menstruation cease entirely. The age of onset of menopause has changed very little over time - even the Ancient Greeks mention the age of 50 as typical. Age of menopause is affected by multiple factors. Maternal menopausal age is predictive of a daughter's menopausal age. Age of menarche does not affect age of menopause. Most agree that race and parity have no effect. Smokers enter menopause at an earlier age than nonsmokers. Although ovarian failure is a major component of menopause, functional alterations also occur at the level of the pituitary. Changes arise in the intrinsic rhythms that control sleep and the neuroendocrine axes. Such changes in the circadian oscillator lead to diminished nocturnal melatonin secretion and altered sleep, decreased responsiveness of the gonadotropin axis to steroid feedback and decreased adrenal steroid production. Aging is also associated with a more general decline in central dopaminergic and noradrenergic neu- ronal function. Estrogen de ciency further exacerbates the dopamine de ciency by increasing the ratio of norepinephrine to dopamine. During menopause, the decrease in ovarian estrogen and inhibin production reduces negative feedback signals to the pituitary and hypothalamus and results in a progressive rise in gonadotropin levels. Because inhibin acts exclusively to regulate FSH (Chapter 1), FSH levels rise disproportionately to luteinizing hormone (LH) levels. When in doubt, persistent elevation of serum FSH levels con rmsthe diagnosis of menopause. Although ovarian estrogen production essentially ceases, the ovary continues to make the androgens testoster- one and androstenedione. Most of this steroid biosynthesis occurs in the hilar cells of the medulla of the gland and very little occurs in the stroma. Hilar cells share a common embryologic origin with testicular Leydig cells, the main androgen-secreting cells in the male (Chapter 5). Although ovarian estrogen production ceases at menopause, post- menopausal women are not completely estrogen de cient. Peripheral tissues such as fat, liver and kidney express the enzyme aromatase and can convert circulating androgens to estrogens. The major difference between direct ovarian estrogen secretion and peripheral conversion is that most of the estrogen produced by the latter process is estrone. Estrone is the estrogen produced from aromatization of androstenedi- one, the major androgen secreted by the postmenopausal ovary and adrenal gland (Chapter 2). Estrone is a very weak estrogen compared with estradiol. In the typical concentrations found in postmenopausal women, estrone does not provide protection against the long-term consequences of estrogen de ciency. Obese postmenopausal women are somewhat protected from this. Fat is a particularly rich source of aromatase activity and obese postmenopausal women can produce substantial amounts of estrone. These high quantities of endogenous estrone provide some protection against the risk of menopausal vaso- motor symptoms and osteoporosis but at a cost. Prolonged exposure of the endometrium to estrogen stimulation that is unopposed by pos- tovulatory progesterone will increase the risk for the development of endometrial hyperplasia and carcinoma (Chapter 42). The endometrium is never converted from proliferative physiology to secretory morphol- ogy and this unregulated growth favors neoplastic change. A similar risk of endometrial stimulation is present in women receiving estrogen alone for postmenopausal hormone replacement. For this reason, women who still have their uterus but require or choose postmenopau- sal estrogen replacement should also be given progesterone in a con- tinuous or cyclic fashion. Signs and symptoms Hot ashes Hot ashes or ushes occur in about 75% of menopausal women. Nocturnal hot ashes often wake a woman from sleep and may produce signi cant sleep deprivation or insomnia. During a hot ash most women note a sensation of pressure in their head followed by a ush of heat or burning. This sensation begins on the head or neck area and passes over the entire body. Sweating invariably accompanies the ush. While there are profound physiologic changes associated with hot ashes, the mechanism by which estrogen de ciency pro- duces this symptom is not known. The physiologic changes include an initial increase in skin conductance and then temperature, a re ec- tion of peripheral vasodilatation. Core body temperature subsequently drops by an average of 0.2°C. Circulating estrogen levels do not change before or after the ash but LH, cortisol, dehydroepiandroster- one (DHEA), androstenedione and the pro-opiomelanocortin (POM-C) derived peptides all do. It is believed that the hot ash represents an initial change in central thermoregulation that elicits a number of compensatory mechanisms. These mechanisms transiently raise, but ultimately reduce the core body temperature to the new set point. Central nervous system catecholamines are involved in hypothalamic temperature regulation and the impact of estrogen de ciency on noradrenergic neuronal function likely has a role in hot ashes. Some hypothesize that estrogen de ciency predisposes to vasodilatation within the hypothalamus. This results in an increase in hypothalamic temperature and a response favoring a reduction in the core body temperature. In addition to hot ashes, most menopausal women experience vaginal atrophy and changes in their breasts and skin. Vaginal atrophy can lead to decreased vaginal lubrication. This may be physi- cally uncomfortable, may predispose to urinary tract infections and may result in dyspareunia during intercourse. These changes are directly related to the loss of estrogen stimulation in target tissues and can largely be reversed by estrogen replacement. Bone changes Bone loss in women actually begins at about age 30. It accelerates at menopause. The most rapid bone loss occurs in the rst 3-4 years after menopause. Bone loss occurs more quickly in women who smoke and in very thin women. African-American race and uoride treatment of the water supply are associated with a lower incidence of osteoporosis. The most common site of osteoporosis-related fractures is the vertebral body, an effect that may be noted clinically as back pain and the develop- ment of a "dowager's hump." The upper femur, humerus, ribs and distal forearm are also frequently affected by postmenopausal bone loss. Upper femoral fractures that involve the hip joint may be life-threaten- ing because of an accompanying risk of venous thromboembolic disease. Osteoporosis resulting from prolonged estrogen de ciency involves a reduction in the quantity of bone without alterations in its chemical composition. Bone formation by osteoblasts is normal in estrogen- de cient women but the rate of bone resorption by osteoclasts is increased. Trabecular bone is affected rst, followed by cortical bone. Estrogen appears to antagonize the effects of parathyroid hormone (PTH) on calcium mobilization. This may occur as a direct effect of estrogen on bone because estrogen receptors have been found on bone cells in culture. Cardiovascular changes Estrogen receptors are present on blood vessels and estrogen appears to clinically decrease vascular resistance and increase blood ow. One potential mechanism by which estrogen may improve blood ow is through its demonstrated ability to decrease the production of endothe- lin, a potent vasoconstrictor, by vascular endothelium. Estrogen therapy is also associated with an increase in high-density lipoproteins and decrease in low-density lipoproteins. Despite these mechanistic ndings, the results of several recent large population studies have suggested that postmenopausal hormone replacement therapy (HRT) may have untoward cardiovascular effects. These results need to be taken in context with risks and bene ts weighed for a particular patient. For instance, one arm of the Women's Health Initiative, which is the largest randomized trial of HRT, showed that use of combina- tions of estrogen and progestin in the treatment of postmenopausal women resulted in seven additional cases of heart disease, eight pul- monary emboli, eight strokes and eight additional cases of breast cancer among 10 000 women treated for 1 year. At the same time, there were six fewer cases of colon cancer and ve fewer hip fractures. This resulted in 20 women who were harmed by therapy out of 10000 undergoing treatment. Although recent data have relaxed prohibitions somewhat, postmenopausal estrogen replacement regimens in the years after release of the results of the Women's Health Initiative have been severely retstricted, with most practitioners limiting therapy to the treatment of hot ashes and vaginal atrophy. When given, estrogen has typically been provided in the lowest dose and for the shortest duration possible. Alternative medications and delivery systems for postmenopausal hormone replacement are under investigation.

Induced Abortion in the United States

Nearly half (45%) of all pregnancies among U.S. women in 2011 were unintended, and about four in 10 of these were terminated by abortion.1 Nineteen percent of pregnancies (excluding miscarriages) in 2014 ended in abortion.1 Approximately 926,200 abortions were performed in 2014, down 12% from 1.06 million in 2011. In 2014, some 1.5% of women aged 15-44 had an abortion.2 Just under half of these women (45%) reported having a previous abortion.3 The abortion rate in 2014 was 14.6 abortions per 1,000 women aged 15-44, down 14% from 16.9 per 1,000 in 2011.2 This is the lowest rate ever observed in the United States; in 1973, the year abortion became legal, the rate was 16.3.4 At 2014 abortion rates, one in 20 women (5%) will have an abortion by age 20, about one in five (19%) by age 30 and about one in four (24%) by age 45.5 WHO HAS ABORTIONS? More than half of all U.S. abortion patients in 2014 were in their 20s: Patients aged 20-24 obtained 34% of all abortions, and patients aged 25-29 obtained 27%.6 Twelve percent of abortion patients in 2014 were adolescents: Those aged 18-19 accounted for 8% of all abortions, 15-17-year-olds for 3% and those younger than 15 for 0.2%.6 White patients accounted for 39% of abortion procedures in 2014, blacks for 28%, Hispanics for 25% and patients of other races and ethnicities for 9%.6 Seventeen percent of abortion patients in 2014 identified as mainline Protestant, 13% as evangelical Protestant and 24% as Catholic; 38% reported no religious affiliation and the remaining 8% reported some other affiliation.6 The vast majority (94%) of abortion patients in 2014 identified as heterosexual or straight. Four percent of patients said they were bisexual, while 0.3% identified as homosexual, gay or lesbian and 1% identified as "something else."6 In 2014, some 46% of all abortion patients had never married and were not cohabiting. However, nearly half were living with a male partner in the month they became pregnant, including 14% who were married and 31% who were cohabiting.6 Fifty-nine percent of abortions in 2014 were obtained by patients who had had at least one birth.6 Some 75% of abortion patients in 2014 were poor or low-income. Twenty-six percent of patients had incomes of 100-199% of the federal poverty level, and 49% had incomes of less than 100% of the federal poverty level ($15,730 for a family of two).*6 The reasons patients gave for having an abortion underscored their understanding of the responsibilities of parenthood and family life. The three most common reasons—each cited by three-fourths of patients—were concern for or responsibility to other individuals; the inability to afford raising a child; and the belief that having a baby would interfere with work, school or the ability to care for dependents. Half said they did not want to be a single parent or were having problems with their husband or partner.7 Fifty-one percent of abortion patients in 2014 were using a contraceptive method in the month they became pregnant, most commonly condoms (24%) or a hormonal method (13%).8 PROVIDERS AND SERVICES The number of U.S. abortion-providing facilities declined 3% between 2011 and 2014 (from 1,720 to 1,671). The number of clinics providing abortion services declined 6% over this period (from 839 to 788). Ninety percent of all U.S. counties lacked a clinic in 2014, and 39% of women of reproductive age lived in those counties.2 In 2014, some 46% of abortion clinics offered very early abortions (at four weeks' gestation or earlier, before the first missed period), and 99% offered the procedure up to eight weeks from the last menstrual period. Seventy-two percent of clinics offered abortions up to 12 weeks, 25% up to 20 weeks and 10% up to 24 weeks.9 In 2014, the average amount paid for an abortion in a nonhospital setting at 10 weeks' gestation and with local anesthesia was $508. The average paid for an early medication abortion (up to 9 weeks' gestation) was $535.9 Eighty-four percent of clinics reported at least one form of antiabortion harassment in 2011. Picketing was reported by 80%, and phone calls by 47%. Fifty-three percent of clinics were picketed 20 times or more in a year. Three percent of clinics reported receiving at least one bomb threat in 2011.10 EARLY MEDICATION ABORTION In September 2000, the U.S. Food and Drug Administration approved mifepristone to be marketed in the United States for nonsurgical abortion. According to U.S. Food and Drug Administration guidelines, medication abortion is approved for abortions up to 10 weeks' gestation. The protocol involves two drugs—mifepristone and misoprostol—one of which can be taken at home following a provider visit. Medication abortions accounted for 31% of all nonhospital abortions in 2014, and for 45% of abortions before nine weeks' gestation.2 In 2014, some 87% of all nonhospital abortion providers—900 facilities—provided one or more medication abortions,2 and 26% of clinics provided only early medication abortion.9 Medication abortions increased from 6% of all nonhospital abortions in 2001 to 31% in 2014, even while the overall number of abortions continued to decline. Data from the Centers for Disease Control and Prevention show that the average time of abortion has shifted earlier within the first trimester; this is likely due, in part, to the availability of medication abortion services.11 SAFETY OF ABORTION A first-trimester abortion is one of the safest medical procedures and carries minimal risk: Major complications (those requiring hospital care, surgery or transfusion) occur at a rate of less than 0.5%.12,13 Abortions performed in the first trimester pose virtually no long-term risk of problems such as infertility, ectopic pregnancy, spontaneous abortion (miscarriage) or birth defect, and little or no risk of preterm or low-birth-weight deliveries.14 Exhaustive reviews by panels convened by the U.S. and UK governments have concluded that there is no association between abortion and breast cancer. There is also no indication that abortion is a risk factor for other cancers.14 Leading experts have concluded that among women who have an unplanned pregnancy, the risk of mental health problems is no greater if they have a single first-trimester abortion than if they carry the pregnancy to term.15 The risk of death associated with abortion increases with the length of pregnancy, from 0.3 for every 100,000 abortions at or before eight weeks to 6.7 per 100,000 at 18 weeks or later.16 INSURANCE COVERAGE AND PAYMENT Most U.S. abortion patients had health insurance in 2014. Thirty-five percent had Medicaid coverage, while 31% had private insurance.6 However, insurance does not necessarily cover abortion services, and even when it does, patients may not use their coverage for a variety of reasons (e.g., because they do not know their plan covers it, they are concerned about confidentiality or their provider does not accept their plan).17 Overall, 53% of abortion patients paid out of pocket for their procedure in 2014.6 Medicaid was the second-most-common method of payment, reported by 24% of abortion patients. The overwhelming majority of these patients lived in the 15 states that allow state funds to be used to pay for abortion.6 Fifteen percent of patients used private insurance to pay for the procedure. Most patients with private insurance (61%) paid out of pocket.6 LAW AND POLICY Since recognizing a woman's constitutional right to abortion in 1973 in Roe v. Wade, the U.S. Supreme Court has in subsequent decisions reaffirmed that right. The Court has held that a state cannot ban abortion before viability (the point at which a fetus can survive outside the uterus), and that any restriction on abortion after viability must contain exceptions to protect the life and health of the woman. Furthermore, any previability abortion restriction cannot create an "undue burden" by placing a substantial obstacle in the path of a woman seeking an abortion. This "undue burden" standard was established in Planned Parenthood v. Casey in 1992 and clarified in the 2016 decision in Whole Woman's Health v. Hellerstedt. The latter affirmed that courts must consider credible evidence when evaluating the constitutionality of abortion restrictions and strike down measures that do not have tangible benefits that outweigh the real-world burdens imposed on women. The Hyde Amendment, in effect since 1977, essentially bans federal dollars from being used for abortion coverage for women insured by Medicaid, the nation's main public health insurance program for low-income Americans. Similar restrictions apply to other federal programs and operate to deny abortion care or coverage to women with disabilities, Native Americans, prison inmates, poor women in the District of Columbia, military personnel and federal employees.18 Although the Hyde Amendment bars federal funds from being used to provide Medicaid coverage of abortion, states may use their own, nonfederal funds. Seventeen states have a policy requiring the state to provide abortion coverage under Medicaid, but just 15 appear to be doing so in practice.19 As of January 1, 2018, all but 10 states had imposed at least one of five major abortion restrictions: unnecessary regulations on abortion clinics, mandated counseling designed to dissuade a woman from obtaining an abortion, a mandated waiting period before an abortion, a requirement of parental involvement before a minor obtains an abortion or prohibition on the use of state Medicaid funds to pay for medically necessary abortions.20-23 In 2014, some 76% of abortion patients were able to obtain an abortion within seven days of calling to book an appointment. The 7% of abortion patients who had to wait more than 14 days between booking an appointment and obtaining the procedure were more likely to have been exposed to disruptive life events or to live in a state with a required waiting period.24 In 2000, a total of 13 states had at least four types of major abortion restrictions, qualifying them as hostile to abortion rights.25 By 2017, 29 states met this definition.26 The proportion of U.S. women of reproductive age living in hostile states rose from 31% to 58% during this time period. In contrast, the number of states that were supportive of abortion rights fell from 17 to 12 between 2000 and 2017.25,26 The proportion of women of reproductive age living in supportive states declined from 40% to 30% over this period.

Ch1 Gonadotropins

Pituitary structure and function There are three lobes to the pituitary gland (hypophysis): the anterior lobe, the posterior lobe and the pars intermedia, a small intermediate structure lying between the anterior and posterior lobe that is actually a subdivision of the anterior lobe. The pituitary is connected to the brain via a small branch of tissue known as the pituitary stalk or infundibulum. The posterior pituitary serves mainly as a storage site for two hormones produced in the hypothalamus: oxytocin and arginine vasopressin (also known as anti- diuretic hormone, ADH). In contrast, the anterior pituitary produces tropic hormones under the regulatory control of the hypothalamus. This control is mediated by neuroendocrine signals from the hypotha- lamus that travel through rich vascular connections surrounding the pituitary stalk. Blood owing through this highly vascular plexus delivers signals to the anterior pituitary gland, regulating production and release of its protein products. There are ve cell types in the anterior pituitary that are associated with tropic hormone production: gonadotropes, lactotropes, soma- totropes, thyrotropes and corticotropes. These speci c cells are responsible for production and secretion of: follicle-stimulating hormone (FSH) and luteinizing hormone (LH); prolactin; growth hormone; thyroid-stimulating hormone (TSH); and adrenocortico- tropic hormone (ACTH), respectively. The thyrotropes and gonado- tropes closely resemble each other histologically because their secretory products, LH, FSH and TSH, are all glycoprotein hormones that stain with carbohydrate-sensitive reagents. LH and FSH are pro- duced by a single cell type, allowing coupled secretion and regulation by a single releasing factor. Control of pituitary gland activity comes largely from the hypotha- lamus with important direct modulation by feedback mechanisms. The hypothalamic nuclei associated with reproduction include the supraop- tic, paraventricular, arcuate, ventromedial and suprachiasmatic nuclei. Neurons in two less well-de ned areas, the medial anterior hypotha- lamus and the medial preoptic areas, are also involved. The magnocel- lular (large) neurons that originate in the supraoptic and paraventricular nuclei project into the posterior pituitary and produce the hormones vasopressin and oxytocin. The parvocellular (small) neurons found in the paraventricular, arcuate and ventromedial nuclei and the periven- tricular and medial preoptic areas produce regulatory peptides that control the tropic hormones produced by the anterior pituitary. Those cells in the hypothalamic nuclei that regulate the pituitary have several functions. They receive signals from higher centers in the brain, generate neural signals of their own and have neuroendocrine capabilities. The higher areas of the brain that connect to the hypotha- lamic nuclei involved with reproduction are the locus ceruleus, the medulla and pons, the midbrain raphe, the olfactory bulb, the limbic system (amygdala and hippocampus), the piriform cortex and the retina. Endogenous opioids also in uence hypothalamic function. The neuroendocrine signals generated within the hypothalamus are mediated by peptide-releasing factors that travel through the hypothalamic-pituitary portal system to their site of action in the pitui- tary gland. Gonadotropin-releasing hormone (GnRH) is the key tropic hormone for regulating gonadotrope cell function and hence, reproduc- tion. A key neural signal in human reproduction arises from what is known as the GnRH pulse generator. The mechanism by which pul- satile GnRH release controls gonadotropin synthesis and secretion remains poorly de ned. At baseline, GnRH secretes from the hypotha- lamus in pulses at a frequency of approximately one pulse per hour. GnRH pulse frequency is most rapid in the follicular phase, slightly slower in the early luteal phase and slowest in the late luteal phase of the female menstrual cycle. In general, rapid pulse frequencies favor LH secretion and slower pulse frequencies favor FSH release. The relationship between pulse frequency and LH and FSH secretion appears to exist in both women and men. Continuous GnRH release inhibits gonadotrope function. This is the basis for the downregulating activities of long-acting exogenous GnRH agonists and antagonists. Thyrotropin-releasing hormone (TRH) and prolactin inhibitory factor (PIF) also have roles in reproductive regulation. Those hypothalamic neuroendocrine peptides that control growth hormone (GH) and ACTH secretion are less directly related to reproduction. Structure of LH and FSH LH, FSH and TSH are structurally similar. They are formed by two distinct, noncovalently bound protein subunits called α and β. The pregnancy-speci c gonadotropin, human chorionic gonadotropin (hCG), is a fourth glycoprotein formed of α and β chains. The α subunit for all four hormones is identical. The β subunit of each hormone differs, conferring functional speci city on each αβ dimer (Fig. 1.1a and b). The β chains for LH and hCG are the most similar with 82% homology. Carbohydrate side chains on both the α and β chains of LH, hCG and FSH add to structural speci city. The carbo- hydrate chains also in uence metabolic clearance rates for the glyco- protein hormones. This effect is most dramatic with the hCG molecule. The β chain of hCG has a 24 amino acid extension at its C terminus that contains four O-linked polysaccharides. This sugar-laden "tail" dramatically slows the clearance of hCG. By prolonging its half-life, the effects of small amounts of this glycoprotein are dramatically enhanced. This characteristic is very important in early pregnancy recognition and maintenance (Chapters 16 and 18). Regulation of FSH and LH The biosynthesis and secretion of FSH and LH are tightly controlled within the reproductive cycle. There are multiple ways in which FSH and LH can be regulated, including alterations in gene transcription, mRNA stabilization, rate of protein subunit synthesis, posttransla- tional glycosylation and changes in the number of gonadotropin- secreting cells. Gonadal steroids exert negative feedback control over FSH and LH synthesis and secretion. Estrogen, androgen and progesterone receptors are present in the gonadotropin-secreting cells of the pitui- tary and in some neurons in the hypothalamus. In the pituitary, the gonadal steroids appear to affect the transcription rate of the genes coding for FSH-β, LH-β and the common α subunit. While there is some evidence that steroids can act at the level of the hypothalamic pulse generator, gonadal steroid hormone receptors do not appear to be present in the GnRH-containing cells of the arcuate nucleus. There is one important exception to the generally inhibitory effect of gonadal steroids on gonadotrope function. In certain situations, estrogen exerts positive feedback on gonadotropin secretion. This is critical to produce the midcycle LH surge in women (Chapter 14) and requires a sustained (>48 h) elevation in circulating estradiol. Estrogen- induced stimulation involves both increased gonadotropin gene expression in the pituitary and alterations in GnRH pulse frequency in the hypothalamus. Inhibin and activin are closely related peptides produced by the ovary, testes, pituitary gland and placenta that in uence gonadotrope function. As suggested by their names, inhibin decreases gonadotrope function and activin stimulates it. Inhibin and activin are formed from common α and β subunits. Inhibin is formed of one α subunit linked to either of two highly homologous β subunits to form inhibin A (αβA) or inhibin B (αβB). Activin is composed of three combinations of the β subunits: activin A (βAβA), activin AB (βAβB) and activin B (βBβB). Activin is a member of the transforming growth factor β (TGF-β) superfamily of growth and differentiation factors that include TGF-β, Müllerian-inhibiting substance (MIS) and bone morphogenic proteins. Follistatin is structurally unrelated to either inhibin or activin. It is a highly glycosylated pituitary peptide that inhibits gonadotrope func- tion but at one-third the potency of inhibin. All three of these peptides have their major in uence on the expression of the FSH-β gene. Of these peptides, inhibin appears to be the most biologically important regulator of the FSH gene, directly suppressing its activity. The other two peptides appear to act within the pituitary cells through locally released second messengers or autocrine peptides. Activin B stimu- lates FSH release. Activins also affect the gonads directly by increas- ing the activity of the aromatase enzyme in the ovary and stimulating proliferation of spermatogonia in the testes. Mechanism of action of gonadotropins There are distinct FSH and LH receptors. The latter also bind the closely related hCG molecule. Receptors for both glycoprotein hor- mones FSH and LH are located in the plasma membranes of the granulosa cells in the ovary and the Sertoli cells in the testes. Ovarian thecal cells and testicular Leydig cells only display LH receptors. In addition to regulating steroidogenesis and gametogenesis, gonadotro- pins regulate expression of their own receptors in a dose-dependent fashion. FSH also induces LH/hCG receptor formation in granulosa and Sertoli cells. Although gonadotropin receptors are normally present in very low concentrations on the cell surface, they have high speci city and af n- ity for their ligands. The interactions between the glycoprotein dimer and its receptor lead to conformational changes in the receptor. This then activates a membrane-associated G protein-coupled signaling system. Although the G protein-coupled cAMP pathway is the princi- pal mediator of both FSH and LH receptor activity, activation of the protein kinase C system can also occur. In addition to activating speci c intracellular signaling processes, binding of the gonadotropin to its receptor also initiates a regulatory function termed desensitization. Desensitization reduces the cell's responsiveness to ongoing stimulation. In the rst phase of desensitiza- tion, the gonadotropin receptor becomes "uncoupled" from its down- stream activity so that it no longer activates adenylate cyclase. In the second, slower phase of desensitization, the degradation rate for the receptors is increased. This latter process is called "downregula- tion." Both are involved in the activities of GnRH agonists and antagonists.

Ch 48 The special cases of syphilis and human immunode ciency virus

Syphilis Natural history of untreated syphilis Syphilis is caused by the spirochete bacterium, Treponema pallidum, which enters the body through miniscule breaks in the skin of the external genitalia that occur during sexual intercourse. Once the spi- rochete has entered, the untreated disease progresses through four consecutive stages: primary, secondary, latent and tertiary syphi- lis. Antibiotic treatment at any stage short of tertiary can prevent the late, life-threatening sequelae of the disease. Syphilis may also be transmitted from a woman to her fetus at any point during pregnancy, with serious consequences. The primary lesion of syphilis, the chancre, develops in venereal locations close to where T. pallidum typically enters the body: the penis, labia, perineum, anus or rectum. Chancres are painless, small papules that persist for 1-2 months and heal spontaneously. The secondary stage of syphilis is a disseminated form. Blood- borne spirochetes populate the dermis throughout the body causing a widespread papular rash over the trunk and extremities. Because the disease is systemic, fever, myalgias, lymphadenopathy, sore throat and headache are common. Secondary syphilis can also be associated with immune complex deposition in the joints, kidneys and eyes, leading to arthritis, glomerulonephritis, nephrotic syndrome and uveitis. Untreated secondary syphilis resolves over 4-12 weeks, leaving the patient symptom free. The subsequent months to years until the onset of symptoms of tertiary syphilis is known as the latent period. Tertiary syphilis usually appears many years after the disseminated stage. Tertiary syphilis can involve multiple organs, including the cardio- vascular and nervous systems. Overall, about one-quarter of untreated patients develop recognizable late (tertiary) complications of syphilis, one-quarter have asymptomatic lesions demonstrable at autopsy and half have no anatomic lesions attributable to syphilis present at autopsy. About half of the patients with symptomatic tertiary syphilis will die as a direct result of the disease, typically of cardiovascular complications. Infection of the placenta and fetus will occur in virtually 100% of pregnant women who suffer the spirochetemia accompanying primary or secondary syphilis. Complications of syphilis in pregnancy include miscarriage, stillbirth, premature delivery and congenital syphilis. The manifestations of congenital syphilis are protean. Its neonatal mortal- ity rate is 50%. Syphilis is treated with penicillin in all but highly allergic patients. Epidemiology of syphilis Syphilis was very common in many parts of the world until antibiotic therapy became available in the 1940s. The prevalence of the disease fell dramatically after World War II but began to increase again in the 1960s. Up to 75% of cases go unreported. Women and men at high risk for contracting syphilis are young, from lower socioeconomic groups, and have multiple sexual partners. Some 10-50 syphilitic organisms are suf cient to cause infection and about one-third of the sexual contacts of an infected person will become infected. The inci- dence of congenital syphilis parallels that in women and is increasing. Mandatory prenatal screening has reduced the incidence of late con- genital syphilis; late or absent prenatal care is the biggest risk factor for congenital syphilis. Biology of T. pallidum Treponema pallidum is a member of the bacterial order Spirochaeta- ceae, and closely related to two other treponemas responsible for human disease: Treponema pertenue, which causes yaws, and T. cara- teum, which causes pinta. Neither electron microscopic examination nor DNA analyses can distinguish between these three organisms. It is believed that the different diseases that develop re ect adaptations of the organism and the host to different points of entry into the body. Treponema pallidum is a relatively fragile organism that cannot survive for more than a few hours outside moist areas of the body. Its microbiology is very poorly understood because the organism cannot be maintained in cell culture. Most of the manifestations of syphilis are secondary to the in am- matory reaction caused by the organism. Polymorphonuclear cells arriving at the site of the inoculum ingest the spirochetes but do not kill them. Lymphocytes and macrophages are recruited to the site. They also surround, but do not kill the treponemes. Antitreponemal antibodies are produced, sometimes in quantities that cause immune complex glomer- ulonephritis. It remains both amazing and unknown how T. pallidum is able to evade host defenses and establish an infection. The site of primary infection is surrounded by a mucoid material composed of hyaluronic acid and chondroitin sulfate that may alter the host defenses. The best clue available to explain the persistence of disease is the nding that delayed type sensitivity to treponemal antigens is absent in secondary syphilis. New spirochetes inoculated into the system are not infectious while the original infection persists. This is a common mechanism in chronic parasitic diseases, called "premunition"; the host resists reinfection but cannot clear the initial infection. Once the systemic phase of the infection is established, spirochetes are present virtually everywhere in the infected tissues. However, in ammation occurs preferentially around small vessels and causes intimal hyperplasia and obliterative endarteritis. The subsequent focal ischemic necrosis and brosis are responsible for the many late mani- festations of the disease. The in ammatory changes caused by the spirochetes are most strik- ing in congenital syphilis. The placenta is diffusely brotic with in ammation and necrosis of the fetal blood vessels in the placental villi. The resulting vascular insuf ciency leads to poor fetal growth (intrauterine growth restriction) and stillbirth. Fibrosis of the liver and spleen cause fetal anemia. Compensatory extramedullary hemato- poeisis promotes hepatosplenomegaly and the development of pleural effusions and ascites (fetal hydrops). Some infants will have a skin rash that closely resembles that of secondary syphilis. A runny nasal discharge loaded with spirochetes (snuf es) may be the only hint of congenital syphilis at birth. The late manifestations of syphilis, both congenital and tertiary, involve vasculitis and parenchymal damage in the central nervous system. Human immunode ciency virus Natural history of untreated HIV infections The rst description of human disease associated with HIV infection surfaced in the early 1980s. Acute infection was reported to cause a "mononucleosis-like syndrome" with fever, malaise, muscle aches, headache, fatigue, generalized rash, sore throat, lymphadenopathy and characteristic mucocutaneous lesions. The rapidity of symptom onset after initial contact may re ect the route of viral entry and the viral load of the exposure. Symptoms of primary infection often persist for 2-3 weeks before resolving spontaneously. The disease then enters an asymptomatic phase. This can last from several months to many years. The length of this symptom-free phase appears to depend on the pathogenicity of the infecting viral strain. Coinfection with other viruses or other sexually transmitted disease (STD) pathogens may speed disease progression. During the asymptomatic phase, viral rep- lication continues within infected lymphoid cells (mainly CD4+ T cells). Infected immune cells are destroyed by the virus and, eventu- ally, the host becomes immunocompromised. In this immunocompro- mised state, the HIV-infected individual is vulnerable to a variety of opportunistic viral, bacterial, fungal and parasitic infections. Oppor- tunistic pathogens such as Pneumocystis carinii, Cryptosporidium and Cryptococcus seldom affect individuals with normally functioning immune systems but can be deadly in those infected with HIV. Patients who are severely immunocompromised are also at risk for the development of certain neoplasms, including Kaposi sarcoma, human papillomavirus-related cervical cancers and some lymphomas. The development of opportunistic infections or neoplasms in a patient infected with HIV de nes the acute immunode ciency syndrome (AIDS). Patient who die of AIDS typically succumb to complications of an opportunistic infection or neoplasm. Epidemiology of HIV infections HIV has infected over 60 million people worldwide, and 35 million are presently living with the disease. The developing world accounts for 95% of infections, with over 25 million of those presently infected living in sub-Saharan Africa. The most important risk factor for acquir- ing HIV infection and succumbing to its complications is poverty. Viral transmission occurs through direct contact with bodily uids, most often semen or blood. Viral spread can occur via sexual contact, via parenteral exposure (intravenous drug abuse and transfusions) or via perinatal transmission. The latter can occur during pregnancy (transmission across the placenta), at delivery or during breastfeeding. Only 25% of children born to untreated HIV-positive mothers will acquire the infection, although this rate can be decreased to less than 1-2% with aggressive antenatal and perinatal therapy. Over 90% of HIV infections occur via heterosexual transmission. HIV is more readily transmitted from the male to female (1 in 500-1000 acts of receptive vaginal intercourse) than female to male (1 in 2000-2500 acts of insertive vaginal intercourse). Biology of HIV HIV is a retrovirus. Its genetic material is carried as RNA wrapped in a viral protein coating. The viral surface expresses a receptor called gp120 that binds speci cally to receptors on lymphoid cells (Fig. 48.1). Binding promotes viral entry into host cells. Host receptors and co-receptors for viral entry include CCR5, a chemokine receptor on macrophages, CXCR4, a chemokine receptor expressed on T cells, and CD4, a marker for T helper cells that is also expressed on macrophages and dendritic cells. Once viral entry has occurred, infected cells will fuse with CD4+ T helper cells. Viral propagation will continue largely in CD4+ cells. After entry into a host cell, the retrovirus uses reverse transcriptase to make a DNA copy of its viral RNA genome. The virus then uses an enzyme called integrase to insert its newly synthesized DNA into the host genome and the host cell machinery makes multiple copies of the HIV genome. The virus nally employs an enzyme called pro- tease to reassemble the viral envelope. Viral particles then exit the host cell via budding to infect surrounding receptor-laden immune cells. Multiple viral progeny will be produced within a single infected host cell before it expires. Reverse transcriptase (RT), integrase and protease are virus-speci c enzymes. They can therefore serve as targets for directed therapeutic interventions. Over 20 FDA-approved medications are now available to treat HIV infections. None are curative and optimal therapies typically use combinations of two to four medications. Available antiretroviral medications inhibit each of the HIV-speci c enzymes: the HIV protease (protease inhibitors), the RT enzyme [nucleoside RT inhibitors (NRTI), non-nucleoside RT inhibitors (NNRTI)], and HIV integrase (integrase inhibitors). Inhibitors of HIV viral entry have recently been released. In developed countries, careful therapeutic interventions, combined with close monitoring of CD4+ T-cell counts and viral loads, have radi- cally improved the prognosis for those infected with HIV. Further advances are challenged by the fact that the HIV reverse transcriptase enzyme makes many mistakes during replication of the viral genome. The virus has no way to readily correct these mistakes. This allows for rapid viral mutation and, unfortunately, the development of resistance to antiretrovi- ral medications. In underdeveloped countries, where the prevalence of disease is highest, medications are scarce or completely unavailable.

Fertilization and the establishment of pregnancy

The egg the cervix into the uterine cavity unless the cervical mucous is recep- tive. This typically occurs at midcycle when estrogen levels are high and progesterone is low. Estrogen softens the cervical stroma and makes cervical secretions thin and watery. Progesterone has opposite effects, a combination hostile to spermatozoa. In the best of conditions, it takes 2-7 h for sperm to move through the uterus to the site of fertilization within the oviduct. Sperm transport results from self-propulsion, aided by the ciliary beating of cells within the uterine lining. Typically, only several hundred sperm reach the oviducts, where they will linger in a quiet state until ovulation occurs. After ovulation, these spermatozoa are reactivated and begin moving toward the egg. The signal that attracts the sperm to the egg is unknown. Human spermatozoa can survive for approximately of 24-48h in the female reproductive tract. Freshly ejaculated spermatozoa are not capable of fertilizing an egg. They acquire the ability to penetrate the cell layers surrounding the oocyte through a process known as capacitation. Although capacita- Sperm nucleus 2 Acrosome reaction 1 Female pronucleus Male pronucleus Zona pellucida At ovulation, the egg is arrested in metaphase of the second meiotic division (Chapter 4). It is surrounded by a proteinaceous sphere called the zona pellucida. Those granulosa cells that adhered to the surface of the zona pellucida and were expelled with the egg from the ovary remain attached as the cumulus. Sperm that fertilize the egg must rst negotiate these surrounding layers before they can penetrate the egg cell mem- brane. The oocyte will remain viable for at least 6-24 h once ovulated. The sperm With coitus, millions of sperm are deposited in the upper vagina. Most will never arrive at the site of fertilization. Abnormal sperm can rarely make this long trip successfully and even most of the healthy sperma- tozoa die along the way. The vast majority leak from the vagina upon liqui cation of the semen. Only a small proportion enters the cervix, where sperm will be found within minutes of coitus. Here they can survive within the epithelial crypts for hours. Sperm cannot traverse tion can be induced in vitro under the proper culture conditions, it occurs in vivo within the female reproductive tract. During capacita- tion, the glycoprotein coat that adheres to the spermatozoa cell mem- branes is initially removed, initiating changes in the surface charge of the sperm membrane and reorganization of that membrane. Capaci- tated sperm change their tail movements from regular undulating waves to whip-like, thrashing movements that propel the sperm forward. At the biochemical level, capacitated sperm acquire increased calcium sensitivity and elevated internal cAMP levels. Capacitation takes several hours both in vivo and in vitro. Sperm capacitation allows for the acrosome reaction. In the absence of an acrosome reaction, a sperm is incapable of penetrating the zona pellucida. Contact of an intact, capacitated sperm with the zona pellu- cida of an egg allows interaction of a speci c sperm cell surface glyco- protein, ZP3, with speci c zona protein. These interactions are likely mediated by the sugars on sperm-egg binding proteins. ZP3-binding induces further calcium in ux into the spermatozoa and intracellular cAMP levels rise. The acrosome swells, its outer membrane fuses with the sperm plasma membrane, and the enzymatic contents of the acro- some are released into the extracellular space surrounding the head of the sperm. This exposes the inner acrosomal membrane and another zona-binding protein, ZP2, to the oocyte zona. ZP2 binding holds sperm near the egg. Proteolytic enzymes released from the acrosome then facilitate penetration of the zona pellucida by the whiplashing sperm. Complete penetration of the zona takes about 15 minutes. Fertilization Penetration of the zona pellucida allows contact between spermatozoa and the oocyte membrane (Fig. 16.1). The germ cell membranes fuse almost immediately and the sperm cell stops moving. The sperm nucleus enters the egg cytoplasm. Three important events are triggered within the oocyte by the rise in intracellular calcium that occurs in the oocyte upon fusion of sperm and egg cell membranes. The egg cell membrane depolarizes, preventing membrane fusion with additional spermatozoa. This is the primary block to polyspermy. It assures that only one male pronucleus is avail- able for fusion with the female pronucleus and protects the diploid status of the zygote. The second event is known as the cortical reaction. Cortical granules lie just beneath the egg cell membrane, and with the cortical reaction they fuse with the membrane and release their contents into the zona pellucida. This hardens the zona and impairs the ability of sperm to bind to it - a secondary block to polyspermy. The third event involves resumption of the second meiotic division of the egg. The second polar body is formed and extruded from the egg, thereby assuring that the female pronucleus is haploid. Again, the diploid zygote is protected. Failure to preserve the diploid state of the conceptus is a frequent cause of early pregnancy failure (Chapter 36). Upon entry into the egg, sperm cytoplasm mixes with that of the egg and the sperm nuclear membrane breaks down. A new membrane forms around the sperm chromatin, forming the male pronucleus. A new oocyte nuclear membrane also forms around the female pronu- cleus. DNA synthesis begins during this period as the haploid pronu- clei prepare for the rst mitotic division of the zygote. The pronuclear membranes break down, the parental chromosomes mix and the met- aphase mitotic spindle forms. At about 24h after fertilization, the chromosomes separate and the rst cell division occurs. During the rst few embryonic cell divisions, no new mRNA is synthesized from the nuclear DNA of the conceptus. The embryo stays the same total size and the size of each individual cell decreases accordingly. Thus, the early embryo uses only maternal cell compo- nents to develop and important signals must be transmitted to the embryo through the oocyte cytoplasm. These signals likely reside in mitochondrial DNA, which is replicated during early embryonic cell division. In fact, mitochondrial DNA is quite stable and can be traced through generations to determine maternal lineage. Establishment of pregnancy After fertilization, a successful pregnancy must implant within the wall of the uterus and inform the mother that pregnancy adaptations must occur. Without these two important events, the zygote will simply wash out of the uterus with the next menses. The cleaving zygote oats in the oviduct for approximately 1 week, progressing from the 16-cell stage through the solid morula (mul- berry) stage to the 32-64 cell blastocyst stage. The latter stage requires formation of the uid-containing blastocyst cavity. The blas- tocyst contains two distinct differentiated embryonic cell types: the outer trophectoderm cells and the inner cell mass. The trophecto- derm cells will eventually form the placenta. The inner cell mass will form the fetus and fetal membranes. It is at the blastocyst stage that the conceptus enters the uterus. During the time that it spends in the oviduct, the conceptus remains surrounded by the zona pellucida. After about 2 days in the uterus, the blastocyst will lose or "hatch" from the zona pellucida. On hatching, the trophectodermal cells of the blastocyst differentiate into trophoblast cells. These simultaneous processes allow trophoblast cells to make direct contact with the uterine luminal epithelial cells. The blastocyst attaches to and invades the uterine lining. Within hours, the surface epithelium immediately underlying the conceptus becomes eroded and nearby cells lyse, releasing primary metabolic substrates used by the blastocyst. The endometrium undergoes dramatic biochemical and morphologic changes called decidualization, a process beginning at the point of attachment and spreading in a concentric wave from the point of implantation. The decidu- alized endometrium will heal over the conceptus so that the entire implan- tation becomes buried within the endometrium. As the embryo invades maternal tissues the trophoblast cells further differentiate into two layers: inner cytotrophoblast cells and an outer syncytiotrophoblast (Chapter 17). The syncytiotrophoblast is a con- tinuous, multinucleated layer that covers the interstitial space and arises from fusion of the underlying cytotrophoblast progenitor cells. Syncytiotrophoblast is active in placental hormone secretion and in nutrient transport from mother to fetus. A separate subset of cytotro- phoblast cells acquires invasive properties and traverses endometrial stroma to reach maternal blood vessels, including the spiral arteries of the endometrium. Appropriate invasion and subsequent remodeling of the spiral arteries by these extravillous cytotrophoblast cells is key to a normal pregnancy outcome (Chapter 38). A number of growth factors are integral to successful implantation: (i) leukemia inhibitory factor, a cytokine; (ii) the integrins, which mediate cell-cell interactions; and (iii) transforming growth factor beta (TGF-β), which stimulates syncytium formation and inhibits tro- phoblast invasion. Epidermal growth factor and interleukin 1β are also important mediators of invasion. Implantation occurs about 7-10 days after ovulation. If the conceptus is to survive more than 14 days after ovulation, the ovarian corpus luteum must continue to secrete progesterone. Human chorionic gona- dotropin (hCG) produced by the developing trophoblast and secreted into the maternal bloodstream acts like luteinizing hormone, supporting the corpus luteum by inhibiting luteal regression (Chapters 14 and 18).

. Ch 31: Secondary amenorrhea

The etiologies of primary and secondary amenorrhea often overlap. Those more commonly associated with primary amenorrhea are dis- cussed in Chapter 30. Most secondary amenorrhea results from ano- vulation. The most common reason is pregnancy; this etiology should be evaluated before considering any other cause. An algorithm for evaluating secondary amenorrhea is shown in Fig. 31.1. Polycystic ovary syndrome (PCOS) is the most common cause of chronic anovulatory amenorrhea. It is a disorder characterized by amenorrhea or oligomenorrhea, physical signs of hyperandrogenism (hirsutism, acne) and the presence of enlarged polycystic ovaries. PCOS pathophysiology can be linked to the combination of: (i) exag- gerated pulsatile gonadotropin-releasing hormone (GnRH) secretion, causing elevated circulating luteinizing hormone (LH) and an increased LH : FSH (follicle-stimulating hormone) ratio; and (ii) defects in insulin signaling for glucose transport and lipolysis, causing insulin resistance (Fig. 31.2). The mechanism for the exaggerated GnRH pulse frequency and amplitude is unknown, but its appearance at puberty suggests an intrin- sic, primary pathogenic defect. Pituitary gonadotrophs are exquisitely sensitive to the frequency and amplitude of GnRH pulses and the pattern present in patients with PCOS causes a relative increase in the secretion of LH with respect to FSH. Ovarian theca cells respond to LH by increasing cholesterol conversion to androgens (Chapter 2). Conver- sion of these androgens to estrogen in the ovary is reduced by a decrease in aromatase activity that accompanies the relative FSH de ciency. Hyperandrogenism, in turn, causes local follicular arrest and anovula- tion and systemic stimulation of sex steroid-responsive hair follicles, resulting in hirsutism and acne. The androgen-producing theca cells in the ovaries of patients with PCOS become hyperplastic and are sur- rounded by an increased number of developmentally arrested primary and secondary follicles, which can be documented ultrasonographically as enlarged ovaries encircled by a "string of pearls." Insulin abnormalities are as important in PCOS as are those in the GnRH pulse generator. In fact, therapy with insulin sensitizers can correct both metabolic and hormonal alterations. In untreated patients, cellular defects in glucose transport result in transient hyperglycemia and reactive hyperinsulinemia. Insulin synergizes with LH to stimulate androgen pro- duction by theca cells and inhibits the hepatic production of sex hormone- binding globulin (SHBG), thereby increasing circulating free androgen. The cellular lipolytic defect in women with PCOS results from a reduction in β-adrenoceptor density on adipocytes and causes increased fat storage and obesity. Obesity, present in over half of women with PCOS, ampli es the abnormalities of insulin resistance and hyperinsulinemia. The somatotropic (growth) axis has also been implicated in PCOS pathogenesis. Growth hormone (GH) and its peripheral mediators, insulin-like growth factors (IGFs), their binding proteins (IGFBPs) and their receptors enhance steroidogenesis by ovarian theca and granulosa cells. Nonobese patients with PCOS have exaggerated GH pulse amplitudes, similar to their exaggerated GnRH pulses. In con- trast, obese women with PCOS have hyperinsulinemia but blunted GH secretion. Because insulin interacts with the IGF system at multiple levels and can bind to the IGF-1 receptor, hyperinsulinemia mimics GH excess. In either case, there will be increased somatotropic activity and excessive androgen production in the ovary. At least 50% of women with PCOS also show functional adrenal hyperandrogenism, making differentiation of PCOS from late-onset congenital adrenal hyperplasia (CAH) dif cult. The exact nature of the adrenal dysfunction in PCOS is unclear, but evidence points to an increase in P450c17 activities in the zona reticularis of the adrenal cortex. LH, insulin and IGF-1 stimulate this enzyme in the ovary to produce androgens. Patients with PCOS with functional adrenal hyper- androgenism have exaggerated adrenal androgen production in response to adrenocorticotropic hormone (ACTH) stimulation. Excessive adrenal androgen production during adrenarche may trigger the onset of PCOS in these women by increasing serum androstenedione that is converted extragonadally to the weak estrogen estrone. Inappropriate estrone pro- duction, in turn, may produce a premature and pathologic trophic effect on the reproductive axis, causing PCOS at puberty. Treatment of PCOS aims to reduce insulin resistance, to establish ovulation when fertility is desired, and to prevent prolonged unop- posed estrogen activity during anovulation and its associated risk for endometrial hyperplasia and cancer. Antiandrogens may be required to treat acne and hirsutism caused by hyperandrogenism. All functional hypothalamic disorders are associated with decreased GnRH pulse frequency and amplitude. CNS input to the GnRH pulse generator can be disrupted by the psychogenic starvation of anorexia nervosa, by strenuous exercise and by stress. In ltrative diseases of the hypothalamus such as lymphoma and histiocytosis, while rare, can also disrupt GnRH secretion. Amenorrhea resulting from excessive prolactin secretion can arise from multiple abnormalities, including prolactin secreting microade- nomas and macroadenomas, hypothyroidism and use of a wide variety of medications (Chapter 32). Premature ovarian failure (POF), the cessation of menses before age 40 in the absence of genetic abnormalities, accounts for 10% of the cases of secondary amenorrhea. Women with POF typically exhibit amenorrhea, elevated gonadotropin levels and decreased circulating estrogens. Many will have hot ashes. In most cases, the exact cause for ovarian failure will not be found. Some cases of POF are associated with autoimmune diseases such as Hashimoto thyroiditis, Addison disease, hypoparathyroidism and myasthenia gravis, or may be part of a polyendocrine syndrome. Antibodies to gonadotropins and gonado- tropin receptors have been found in some patients. Others lack antibodies, but carry genetic mutations in LH or FSH receptors. Occa- sionally, ovarian failure is temporary and pregnancies have followed an apparent cessation of ovarian function. Intrauterine synechiae or adhesions occlude the uterine cavity in Asherman syndrome. Because the condition may develop after an intrauterine infection or postpartum curettage for heavy bleeding, it is thought that these procedures can inappropriately remove deep endometrial layers and destroy the basal crypts and glands necessary for endometrial regeneration. The scarring associated with Asherman syndrome can totally obliterate the uterine cavity, although milder degrees of scarring can also cause amenorrhea. Direct injury and local paracrine dysfunction may both be involved. Hypothyroidism is associated with menstrual irregularities and amenorrhea. Thyroxine can increase estrogen and progesterone secre- tion by cultured human granulosa cells and thyroid hormone de - ciency may adversely alter ovarian steroidogenesis. Also, the increased hypothalamic secretion of thyrotropin-releasing factor (TRF) accom- panying primary hypothyroidism will stimulate prolactin secretion. The resulting hyperprolactinemia inhibits pulsatile GnRH secretion and causes menstrual irregularities (Chapter 32). CAH, Cushing syndrome and obesity all are associated with excess androgen production. Although adrenal androgens (DHEA and DHEA-S; Chapter 2) are relatively weak, their presence in pathologic amounts can lead to signi cant androgenic effects. Most effects occur after conversion to more potent androgens and estrogens in peripheral cells such as adipocytes. In women, the resultant noncyclic, gonadotropin-independent sex steroid secretion interferes with normal cyclic secretion of FSH and LH by the pituitary and causes oligo- or anovulation. In empty sella syndrome, the bony structure surrounding the pitui- tary gland is attened and appears enlarged and empty. Some patients with an apparently empty sella have headaches and no endocrine dysfunction. Others have single or multiple endocrinopathies includ- ing gonadotropin de ciencies and hyperprolactinemia. The cause of empty sella syndrome is unknown. The pituitary gland is particularly vulnerable to hypotensive injury during pregnancy. Pituitary infarction associated with postpartum hemorrhage and shock is called Sheehan syndrome. In Sheehan's original description, patients presented with panhypopituitarism. Such severe forms of Sheehan syndrome are rarely encountered in modern obstetric practice, but partial forms occasionally are. The severity of the injury determines the speci c pituitary functions affected and loss occurs in a fairly predictable order. Most vulnerable is GH secretion. More severe cases will impair, in decreasing order of frequency, pro- lactin, thyroid-stimulating hormone and ACTH secretion.

. Ch 17: Placental Structure and Function

The human placenta is the sole interface between the mother and her developing embryo/fetus. Humans differ from most other mammals in that maternal blood comes into direct contact with fetally derived placental tissues. This organization characterizes the hemochorial pla- centa through which all maternal nutrients and fetal wastes must pass. The placenta is a very active organ that has specialized mechanisms to promote fetal growth and survival. These include, but are not limited to, ef cient gas exchange, active transport of energy substrates, immunologic tolerance of the fetal allograft and fetal acquisition of maternal immunity. Placental morphology After it enters the uterus, the human blastocyst resides within the uterine cavity for 2-3 days prior to implantation into the decidualized uterine endometrium (Chapter 16). Implantation can be divided into three distinct processes: apposition of the blastocyst to the endometrial epithelium at the site of implantation, a brief period of stable adhesion of the blastocyst to this epithelium and invasion of the developing embryo into the uterine decidua. The signals governing these pro- cesses are complex and involve active maternal and fetal participation. Apposition requires the secretion of soluble mediators by uterine epithelia and the blastocyst that include interleukins, prostaglandins and leukemia inhibiting factor (LIF). Adhesion is promoted by the expression of ligands on the surface of the developing embryo that speci cally bind to receptors expressed on the uterine lining at the site of implantation. One receptor-ligand pair that has been implicated in embryo adhesion is heparin-binding epidermal growth factor and heparin sulfate proteoglycans. Also important in the adhesion process is a family of adhesion molecules expressed on uterine epithelia in a time-speci c and hormone-dependent fashion: the integrins. Invasion of the blastocyst into the maternal uterine decidua requires an altera- tion in the expression of embryonic surface molecules, from those promoting adhesion to the endometrium to others that stimulate inva- sion of vascular structures. During invasion, the embryo also begins to secrete proteases that digest between the cells of the decidua and allow invasion to areas deep within the uterine lining. The blastocyst is comprised of two populations of cells (see Fig. 16.1): one will become the fetus, the other, the placenta. At the blasto- cyst stage, the embryo is characterized by a uid- lled cavity (the blastocele) surrounded by a layer of trophectoderm cells. The troph- ectoderm will develop into the placenta. Within the trophectoderm shell is a collection of cells called the inner cell mass. All nonplacental fetal tissues will arise from the inner cell mass. During implantation, trophectoderm cells begin to differentiate into cellular subtypes that will characterize the mature placenta. The mature placenta is comprised of a mass of tree-like placental cotyle- dons called villae, which are bathed in maternal blood (Fig. 17.1). Blood enters the space between the villae through low-resistance, high- ow vessels that branch from the maternal uterine spiral arteries. Fetal vessels are located within the core of each placental cotyledon. Loose connective tissue and layers of trophoblast cells surround each fetal vessel. The inner layers of the trophoblast shell around the fetal

42 Ovarian neoplasms

The overwhelming majority of ovarian masses are benign and the lifetime risk of developing ovarian cancer is about 2%. Age is the most important factor in determining risk of malignancy. Adnexal masses are common during the reproductive years. During this stage of life, such masses are usually caused by functional ovarian cysts, benign neoplasms of the ovary or by postinfectious changes in the fallopian tubes. In girls under 20 and in women over 50, about 10% of all pal- pable ovarian masses are malignant. Between 85 and 90% of ovarian cancer occurs in postmenopausal women. Benign neoplasms of the ovary Benign and malignant neoplasms can develop from any cell type found in the ovary. Simple cysts can be functional and form at the site of ovulation or during the development of the corpus luteum. These are very common and distinguishable from true neoplasms by their transi- tory nature. They typically disappear within 6 weeks of discovery. Complex or solid masses and those that are persistent are more likely to be truly neoplastic and require histologic diagnosis. Dermoids are a unique type of benign ovarian tumor that arises from more mature germ cells than the other germ-cell tumors (GCTs) found in women (Table 42.1). On gross examination, dermoids may contain hair, bone, cartilage and large amounts of greasy uid that rapidly becomes sebaceous at room temperature. On histologic exami- nation, the tumors contain disarrayed clusters of many of the cell types normally seen in fetuses. Like other GCTs, the molecular event(s) that lead to activation of the germ cells in dermoids can occur in utero and benign ovarian teratomas have been detected in the fetus and newborn infant. Ovarian dermoid tumors display abnormalities in imprinting and are discussed in more detail in Chapter 45. Ovarian cancers Ovarian cancer is the most lethal gynecologic malignancy. While over 90% of testicular malignancies are GCTs, 65-70% of ovarian malig- nancies are epithelial cell cancers. GCTs of the testis have good early detection and high cure rates (Chapter 40). Ovarian epithelial cell cancers are usually detected after widespread intraperitoneal dissemi- nation. At this point, cure is almost impossible. There are ve distinct histologic types of epithelial ovarian tumors: serous, mucinous, endometrioid, clear cell and Brenner. Of the ve, serous neoplasms account for almost half of all tumors. Mucinous tumors comprise about 25%, endometrioid tumors about 5%, clear cell cancers under 5% and Brenner cell tumors 2-3% of the total. The remainder of ovarian cancers are too poorly differentiated at diagnosis to be classi ed. Epithelial ovarian cancer typically spreads both locally and by intra- peritoneal dissemination. Contiguous spread is to the fallopian tube and uterus. Dissemination occurs to the contralateral ovary and peri- toneum. Implants of epithelial ovarian cancer may be found on the cul-de-sac, bowel, mesentery, omentum and diaphragm. Malignant ascites forms when diaphragmatic metastases block the lymphatic drainage of the peritoneal cavity. Patients with these cancers may not develop symptoms until the tumor mass compresses other intraperito- neal organs or the associated ascites causes abdominal bloating, dys- pepsia or urinary frequency. This relative lack of early symptoms leads to late diagnosis and poor prognosis. Treatment for epithelial ovarian cancer involves cytoreductive surgery and aggressive chemotherapy, and only 15% of patients with advanced disease will survive. These tumors often develop resistance to chemotherapy. When disease is con ned to the ovary, survival dramatically improves to 50-90%. Unfortunately, ovarian epithelial tumors are seldom diagnosed at this early stage. About 15% of all epithelial ovarian cancers have histologic and biologic behaviors that are neither clearly benign nor frankly malig- nant. These "borderline" ovarian carcinomas share a common genetic lineage with their corresponding benign cystic neoplasms. Borderline tumors have a 95% 10-year survival rate but can recur as many as 20 years after excision. Late recurrences are often identical to the primary tumor, but malignant transformation to high-grade epithelial ovarian cancer can occur in a minority of cases. Epidemiology of epithelial ovarian cancer Family history is the most important risk factor, followed by age. The mean age of disease onset is 59 years. Other risk factors are early menarche, late menopause, regular and uninterrupted menstrual cycles, short menstrual cycle length, low parity and a history of infertility. High parity and use of oral contraceptives reduce the risk of ovarian cancer. Both also decrease the number of lifetime ovulation events. These epidemiologic data suggest that the number of ovulations over a lifetime is signi cant in the pathogenesis of the disease. As with other prevalent epithelial cancers, environmental factors in uence the development of ovarian cancers, with the highest rates being found in highly industrialized countries. Japan is the single notable exception, with rates of malignant neoplasms of the ovary that are among the lowest in the world. However, the rates in Japanese immigrants in the USA approach those of Caucasian natives within two to three generations, suggesting that carcinogens in the immediate environment are responsible. Chemical carcinogens from the outside world can reach the pelvic peritoneum of women through the vagina and upper reproductive tract. In fact, investigators have shown that more women with ovarian cancer use talc as a dusting powder on their perineum or sanitary napkins than matched controls. The association between talc and ovarian cancer is also biologically plausible. Talc is chemically related to asbestos and ovarian cancer is similar to the mesotheliomas that can develop after pulmonary exposure to asbestos. Familial ovarian cancer Various syndromes have been have been associated with increased risk for the development of cancers. Three include a predisposition to ovarian cancer: familial ovarian cancer syndrome, hereditary breast/ ovarian cancer syndrome and Lynch cancer family syndrome II (hereditary nonpolyposis colorectal cancer syndrome, HNPCC). These syndromes account for less than 10% of ovarian cancer diagnoses. Virtually all the hereditary breast/ovarian cancers and site-speci c ovarian cancer syndromes are caused by mutations in the tumor sup- pressor genes BRCA1 or BRCA2. Individuals with BRCA1 mutations have a 20-fold increase in their risk for developing both breast and ovarian cancers, and those with BRCA2 mutations a 5-10-fold increase in their risk for developing ovarian cancer. The estimated frequency of BRCA1 mutations in the general population is 1 in 800, but is greater than 1 in 100 among Ashkenazi Jewish women. BRCA2 muta- tions have a very similar carrier frequency among the Ashkenazi and a frequency of 1 in 250 among Icelanders. HNPCC is caused by mutations in any one of several genes impor- tant in DNA mismatch repair. The most common extracolonic malig- nancy in women with HNPCC is endometrial cancer, followed by ovarian cancer. Pathogenesis of nonfamilial epithelial ovarian cancer The typical advanced stage of epithelial ovarian cancers at clinical presentation, combined with the lack of identi able precursor lesions for the more common serous and mucinous adenocarcinomas, have made biologic study of their development dif cult. Originally, some investigators proposed that epithelial ovarian cancers arise in small inclusion cysts that develop when surface epithelial cells become entrapped in the physical defects left in the ovarian surface after ovula- tion while others hypothesized that the ovarian epithelium is a coe- lomic mesothelium that is more prone to metaplasia than other epithelia. More recent studies suggest that many ovarian tumors may actually originate in other pelvic organs and involve the ovary second- arily. Serous tumors may arise from fallopian tube epithelium that either implants or is trapped in the ovary at the time of ovulatory capsule disruption. Endometrioid and clear cell tumors, both of which are associated with the clinical condition of endometriosis (Chapter 34), may arise when endometrium menstruates retrograde onto the ovary although coelomic metaplasia may also be involved. Metaplasia of tissue at the tubal mesothelial junction may give rise to mucinous and Brenner tumors. It has been argued by some that ovarian malig- nancies are more appropriately classi ed into two groups of tumors based both on morphology and molecular genetic features. When this is done, the members of one group each share lineage with a paired benign neoplasm and behave rather indolently while the other group frequently displays tumor suppressor abnormalities that involve p53, the product of a tumor suppressing cell checkpoint gene located on chromosome 17p, and progress rapidly. The rst group is comprised low-grade serous, low-grade endometrioid, clear cell, mucinous and transitional (Brenner) tumors. Each histologic group exhibits a distinc- tive molecular genetic pro le and all lack p53 mutations. The second group includes high-grade serous carcinoma, undifferentiated carcino- mas and mixed mesodermal tumors (carcinosarcoma). As with other malignancies, ovarian cancer probably develops after multiple genetic "hits" cause a cell to display invasive, neoplastic behavior. One "hit" typically involves activation of an oncogene and the second "hit" involves the loss of one or more genes with tumor suppressor activity. BRCA1 and BRCA2 are tumor suppressor genes and inheritance of one abnormal allele makes "second hits" a high statistical probability. Other ovarian malignancies Only 10% of ovarian cancers are GCTs. These occur largely in girls and young women. Like GCTs in men, GCTs in women arise from immature germ cells and include ve distinct histologic types: dys- germinomas, choriocarcinomas, endodermal sinus tumors (yolk sac carcinomas), embryonal carcinomas and teratomas. The dysger- minoma is the female equivalent of the seminoma. GCTs of the testes are typically detected early in their development; GCTs of the ovary are not. For this reason, far less is known about GCT tumorigenesis in the female than in the male (Chapter 40). Stromal cell tumors are the rarest ovarian malignancies, account- ing for 5% of the total. They may contain granulosa, theca, Leydig or Sertoli cells, and usually make large amounts of steroid hormones: granulosa or theca cell tumors make estrogens and Leydig or Sertoli cell tumors make androgens. The occurrence of stromal cell tumors is not age dependent. Those secreting androgens can cause virilization while those secreting estrogens can cause endometrial hyperplasia and irregular vaginal bleeding.

. Ch 25: Contraception

The risk of pregnancy without contraception is 2-4% for each unpro- tected act of intercourse. In 100 women using no contraception, 85 pregnancies occur per year. Approximately half of all pregnancies in the developed world are unplanned and many of these women report using some form of reversible birth control at the time they became pregnant. Only absolute abstinence completely prevents pregnancy. While no form of contraception is perfect in sexually active women, helping patients to choose a contraceptive method that they are able to use consistently and correctly can decrease unintended pregnancy (Fig. 25.1). With perfect use, oral contraceptives (OC) are nearly as effective as long-acting reversible contraceptives (LARC), such as the intrauterine device (IUD), progesterone intramuscular injection and progesterone implants. However, with typical use, LARC methods are approximately 10 times more effective. "Natural" family planning Natural family planning or fertility awareness aims to avoid conception by abstention from intercourse during the woman's fertile period. It makes use of a calendar and some indicator of ovulation (basal body temperature measurements, cervical mucus characteristics or commercial ovulation prediction kits). Intercourse is avoided during the so-called fertile period at ovulation and for several days before and after. Natural family planning requires a highly motivated couple, regular menstrual cycles and the willingness to tolerate a failure rate of up to 25%. The method has no medical side effects and is accepted by virtually all religions. Barrier methods There are three general categories of barrier contraception: condom, diaphragm and cervical cap. All work by preventing spermatozoa from entering the woman's uterus and fertilizing an egg. Barrier methods are good choices for individuals who want to limit contraceptive ef - cacy to a particular sexual episode. They are readily reversible and can be used in conjunction with the timing methods associated with natural family planning. The most serious side effects of barrier methods occur in individuals with an unknown latex allergy. Condoms that t over the penis are more widely available than condoms that t inside the vagina (the female condom). Male condoms may be made from latex rubber, polyurethane or animal intestines; each provides a different "feel" or sensitivity for the man during intercourse. Female condoms are typically made of polyurethane. Intact condoms stop sperm and infectious agents from entering the vagina and so can prevent transmission of HIV and other sexually transmitted diseases. They must be carefully removed after ejaculation to avoid spilling semen from the condom into the vagina. The failure rates of condoms are 3-6% with perfect use and 15% with typical use. The diaphragm is a soft latex or plastic dome that ts inside the vagina and covers the cervix. Because some sperm may be able to bypass the diaphragm and gain access to the uterus, spermicide is placed in the dome of the diaphragm. Diaphragms are individually tted by a clinician and require some training for proper insertion and removal. A diaphragm should be left in place for 6-8h after inter- course, and additional spermicide placed into the vagina if more epi- sodes of intercourse occur before it is removed. Diaphragms partially protect against HIV and other sexually transmitted diseases. Some women develop bladder or vaginal infections during diaphragm use. The failure rate of a properly tted diaphragm with perfect use is about 6%; it rises to 15% with typical use. Cervical caps are similar to, but smaller than, the diaphragm. They are individually tted to tightly cover the cervix. Failure rates are similar to those of the diaphragm. Cervical caps are not widely available. Spermicides These are chemicals that kill sperm by disrupting their outer cell membranes. The most commonly used are nonoxynol-9 and octoxy- nol-9. Spermicides are available suspended in one of three vehicles: foam, jelly or wax suppositories. Spermacides are recommended for use with a barrier method, because the failure rate of spermicide used alone is up to 30%. There are few absolute contraindications to their use. They have an unpleasant taste and can cause an allergy in some users. Spermicide use may cause in ammation of the female genital tract and has been associated with an increase in the transmission of sexually transmitted infections, including HIV. Intrauterine devices The IUD is a small T-shaped device, placed into the uterine cavity and attached to a mono lament thread that hangs into the vagina, allowing the user to con rm that it remains in place. The modern IUD provides safe, long-acting, highly effective and rapidly reversible contraception with few side effects. The precise contraceptive mechanism of the IUD is not known, but it is thought to work by preventing fertilization as well as causing the endometrium to be inhospitable for implantation. The 10-12 year copper IUD produces a local in ammatory response in the endometrium and excess prostaglandin production. The copper ion competitively inhibits a number of zinc-requiring processes in sperm activation and endometrium/ embryo signaling. The 3- and 5+-year progestin-releasing IUDs thickens cervical mucus, creating a barrier to sperm penetration into the upper genital tract. Additionally, the progestin disrupts the normal proliferative- to-secretory sequence of endometrial maturation. Historically, IUDs, such as the Dalkon Shield, were associated with increased risk for medical complications and reproductive damage among users who were infected with sexually transmitted pathogens. This increased risk was likely due to the braided IUD tail, which allowed bacteria to ascend into the upper genital tract. The mono la- ment string, used on all modern IUDs, does not have this risk. In women at high risk for sexually transmitted infections (STIs), screen- ing should be performed prior to IUD insertion. Women should be advised to use a barrier method for prevention of HIV and other STIs. Side effects of the copper IUD include increased menstrual bleed- ing, iron-de ciency anemia and dysmenorrhea. The progestin IUD reduces menstrual ow and may be used to treat menorrhagia and adenomyosis. The IUD is highly effective, with a failure rate <1% per year. If pregnancy occurs, it is more likely to be ectopic in location. However, compared with women using no form of contraception, women with IUDs still have a reduced risk of ectopic pregnancy. Hormonal contraception Combination oral contraceptive pills (often called OCPs) are the most widely used form of hormonal contraception. They include a synthetic estrogen (ethinyl estradiol or mestranol) combined with a variety of synthetic progestins and are typically taken orally for 21 con- secutive days of every 28 and allow monthly withdrawal bleeding. The progestin component of combination OCPs varies in its activity on pro- gesterone receptors, androgen receptors and mineralocorticoid receptors. The estrogen and progestin dosages in monthly combination OCPs may be constant over the 21 days or may be sequentially modulated (phased or triphasic pills). Some newer combination oral contraceptive regimens provide continuous rather than monthly exogenous hormone cycles, often allowing endometrial sloughing only 3-4 times per year. Combination OCPs prevent pregnancy by multiple mechanisms, including inhibition of ovulation, thickening of cervical mucus to prevent sperm transport and alteration of the uterine lining to block implantation. OCPs have bene ts beyond pregnancy prevention, including decreased risk of pelvic in ammatory disease (PID), benign breast disease, anemia and endometrial and ovarian cancer. They are not totally risk free, however, and are associated with increased risk of thromboembolic disease, nonthrombotic stroke and gallbladder disease. Women over 35 who smoke should not use combination OCPs. Failure rates are <1% with perfect use and about 8% with typical use. To be effective, OCPs must be taken in the correct order on a daily basis. Combinations of estrogen and progestin are also available for contracep- tion in nonoral formulations. These include transdermal patches, injections and vaginal rings. All have ef cacy similar to combination OCPs, and may have reduced metabolic side effect pro les. Progestin-only contraceptives can be administered orally, by intra- muscular injection or as a subdermal implant. All work by thickening cervical mucus and altering the endometrial lining of the uterus. The oral form of the progestin-only contraceptive, often called the mini- pill, is useful in women with contraindications to estrogen such as breastfeeding or high thrombotic risk. With perfect use, the mini-pill has a failure rate comparable with OCPs. However, the half-life of the mini-pill is short, with nearly undetectable plasma levels at 24 h. Thus, to maximize effectiveness, the mini-pill requires precise compliance with all 28 active pills taken at the same time daily. Depo-medroxyprogesterone acetate (DMPA) is a progestin contra- ceptive given as an intramuscular injection every 12-14 weeks. Common side effects include irregular bleeding, particularly in the rst 6 months of use, and weight gain. Because of the length of action of DMPA, side effects may persist until the medication is cleared and return to fertility may be delayed. The original six-capsule subdermal levonorgestrel progestin implant (Norplant) has been replaced with an equivalent two-capsule system (Jadelle, 5 years of use), and a single capsule subdermal etonorgestrel implant (Implanon, 3 years of use). Insertion and removal are gener- ally quick and uncomplicated, but must be performed by a trained clinician. Side effects include irregularly irregular vaginal bleeding. Hormonal emergency contraception can be effective in prevent- ing pregnancy if taken within the given time interval after unprotected intercourse or a contraceptive failure. Plan B, consisting of 1.5mg levonorgestral, prevents pregnancy using the same mechanisms as other progestin contraceptives if taken within 120 h of exposure. Com- bination estrogen-progestin emergency contraception may also be used up to 120 h following exposure; however, the combined hormonal regimen has more side effects and a lower effectiveness than the progestin-only regimen. The copper IUD may also be used for emer- gency contraception up to 5 days after unprotected intercourse. Sterilization Sterilization of both men and women are surgical methods of perma- nent contraception. Sterilization prevents the gametes from reaching the point of fertilization. In women, sterilization is commonly performed by laparoscopic tubal ligation. Tubal ligation interrupts the fallopian tubes and may involve the use of tying, blockade, cautery, partial excision or banding. Ten-year cumulative failure rates for female sterilization are 0.75- 3.5%, depending upon the method. If a pregnancy does occur after tubal ligation, up to 50% are in an ectopic (tubal) location because of the blockage of the fallopian tube. Transcervical sterilization involves placement of micro-inserts into the fallopian tubes using a hysteroscope. This method requires no incision and can be performed in a doctor's of ce. Disadvantages include the need to wait 3 months for tubal occlusion to occur and con rmation of occlusion using a radiographic dye test called a hysterosalpingogram. Failure rates appear similar to laparoscopic methods. The sterilization procedure used in men is called a vasectomy. It involves bilateral interruption of the vas deferens as they leave the testes in the scrotum. Surgical methods for interruption include partial excision, cautery or tying. Vasectomy is typically 100% effective but requires a 3-month waiting period and multiple postprocedure ejacula- tions to clear the vas deferens of previously produced sperm.

Labor Abnorm

Timely onset of labor and delivery has an important role in pregnancy outcome. Both preterm and postterm births are at higher risk for poor outcomes than pregnancies delivered at term. Preterm labor Preterm labor is the onset of labor before 37 weeks' gestation. It is the nal common pathway for a number of conditions that induce uterine contractions at a time when the uterus is normally quiescent. Preterm labor complicates 7-10% of all pregnancies and is a very large contributor to perinatal morbidity and mortality. Although over half the cases of preterm labor occur without warning, some factors do carry an identi able risk: multiple gestation, uterine anomalies, third trimester bleeding, intrauterine infection, excessive amniotic uid volume, maternal smoking and a history of prior preterm delivery. There have been many unsuccessful attempts to use risk scoring, close clinical observation and home uterine contraction moni- toring to predict women at high risk for preterm labor. Several bio- chemical markers suggest increased risk of preterm labor: raised salivary estriol, which re ects activation of the fetal hypothalamic- pituitary-adrenal axis, and cortisol-releasing hormone, which is syn- thesized by the placenta (Chapters 19 and 22). Fetal bronectin is normally restricted to the fetal compartment but will appear in vaginal secretions of women who are at risk for preterm delivery. Therefore the absence of fetal bronectin in maternal vaginal secretions is highly predictive of women who will not experience preterm labor. Potential mechanisms for preterm labor The normal mechanisms involved in labor (Chapter 22) predict the pathways for stimuli that start labor prematurely. For instance, intrau- terine infection is associated with an elevation in the amniotic uid levels of the cytokines interleukin-1β, interleukin-6 and tumor necro- sis factor α (TNF-α). Products of the cyclo-oxygenase and prostag- landin pathways are also elevated in patients with intrauterine infections. Cytokines and prostaglandins act synergistically to stimu- late the myometrium. Their premature elevation with intrauterine infection could activate the uterus prematurely. Recently, thrombin has been shown to be an extremely potent uterotonic agent. The increase in thrombin production that accompanies bleeding in pregnancy may cause preterm labor. Multiple gestations and excessive amniotic uid excessively stretch the myometrial syncytium. While this may stimu- late muscle activity, it is unclear how ber stretching produces the regular, coordinated contractions of labor. Pharmacologic interventions In some cases of preterm labor, contractions represent an attempt by the uterus to expel the fetus from a hostile intrauterine environment. This may be the goal when premature labor accompanies intrauterine infection. It is usually not prudent to intervene by attempting to stop labor in these clinical situations. When the cause of preterm labor does not independently place the fetus in danger, pharmacologic attempts to stop the premature contractions may be used (Fig. 37.1). Several agents, called tocolytics, are available to inhibit premature uterine contractions. Tocolytics work by interrupting one of four processes: (i) intracellular Ca2+ homeostasis; (ii) myosin phosphorylation; (iii) prostaglandin synthesis; and (iv) oxytocin binding to its receptors (Fig. 37.1). Calcium ions are required for normal myometrial contractions. Magnesium sulfate (MgSO4) acts as a competitive antagonist for Ca2+ and is a commonly used tocolytic. High extracellular magnesium concentrations inhibit Ca2+ entry into myometrial cells via voltage- operated channels. In addition, intracellular magnesium competes with Ca2+ for binding sites on calmodulin. Decreased calcium-calmodulin binding decreases the activity of myosin light chain kinase and muscle contraction. Nifedipine and nitrendipine are type II (dihydropyridine) calcium channel blockers. They prevent Ca2+ in ux through the cell membrane into the myometrial cells via the voltage-operated Ca2+ channels. Beta-adrenergic agonists, such as ritodrine, salbutamol, iso- xsuprine and terbutaline, bind to β2-adrenergic receptors on the myo- metrial cell membrane, activate G proteins and increase intracellular cAMP levels. An increase in cAMP levels activates protein kinase A. Activated protein kinase A inhibits myosin light chain phosphoryla- tion. Prostaglandins E and F2α stimulate uterine contractions. The tocolytic, indomethacin, reduces prostaglandin production. It competi- tively inhibits cyclo-oxygenases that are necessary for conversion of arachidonic acid to prostaglandins. Oxytocin antagonists bind to the oxytocin receptor but do not activate it. Antagonist-binding blocks activation by the agonist oxytocin. Progesterone prophylaxis has been shown to reduce the rate of preterm birth among women with a history of spontaneous preterm delivery. The mechanism of action of the sup- plemental progesterone is not known. Postterm pregnancy Postterm pregnancy refers to a pregnancy that has extended to or beyond 42.0 weeks' gestation or 294 days from the rst day of the last normal menstrual period. About 2% of pregnancies dated by rst trimester ultrasound go postterm. The cause of postterm pregnancy is largely unknown. Risk factors include rst pregnancy, male fetus, obesity, prior postterm pregnancy and maternal postterm birth. The latter two factors suggest that maternal genetic factors may have a role. Interesting recent data indicate that paternal genes expressed in the fetus may also be involved. Early reports that placental sulfatase de - ciency and fetal anencephaly are associated with postterm pregnancy have not been corroborated. Postterm pregnancy is linked to increased maternal and fetal risk. Labor abnormalities and cesarean deliveries increase because of fetal overgrowth and placental dysfunction. Fetal risks include still- birth, asphyxia and birth injury from overgrowth. Management of the postterm pregnancy may include induction at 41.0 weeks' gestation or expectant management with close fetal surveillance. Placental abnormalities Placental abruption is de ned as premature separation of the placenta prior to delivery of the fetus. Typical symptoms of placen- tal abruption are vaginal bleeding and abdominal pain that are often accompanied by frequent prolonged uterine contractions, uterine ten- derness and fetal distress. Placental abruption complicates about 1% of all births. Severe abruptions can result in stillbirth (Chapter 36). Risk factors for placental abruption that precedes labor include mater- nal trauma, hypertension, uterine anomalies, inherited and acquired clot- ting disorders, abruption or pre-eclampsia in a prior pregnancy, poor fetal growth, cocaine use, cigarette smoking and acute intrauterine infection. Rupture of the fetal membranes, either prior to the onset of labor or during labor in the presence of excess amniotic uid, is also associated with increased risk for placental abruption. Most commonly, the cause of the placental separation is the rupture of maternal vessels in the decidua basalis next to the placental villi. Rupture of vessels may result from acute trauma, high intravascular pressures or from chronic in ammation and/or necrosis. Maternal blood in ltrates into the decidua and lifts it off of the placenta. The resulting hematoma may stay small or it may enlarge to completely separate the placenta from the uterine wall. Thrombin, an important component of the clotting cascade, is released from the decidua in response to the local hypoxia that accompanies abruption. Thrombin is a very potent uterotonic agent; its release likely produces the exag- gerated uterine activity seen with abruption. Thrombin also induces expression of in ammatory cytokines, leading to additional vascular disruption. The detached portion of the placenta cannot exchange gases or deliver nutrients for the duration of the pregnancy. Pregnancy outcome is largely dependent on the size of the separation. The amount of vaginal bleeding from a placental abruption is not a good indicator of the extent of the separation because some or all of the bleeding can be concealed within the uterus. In cases of abruption severe enough to kill the fetus, maternal disseminated intravascular coagulation can develop due to consumption of available clotting factors by the massive amounts of released thrombin. Management of placental abruption depends on severity and gestational age. Placenta previa refers to the presence of placental tissue overly- ing or extremely close to the internal os of the cervix. It occurs in 5-6% of rst trimester gestations; however, placental migration away from the cervix results in an incidence of 0.5% in the third trimester. The diagnosis is made by ultrasound examination of the pregnancy within the uterus. Risk factors for placenta previa include prior cesar- ean delivery and uterine curettage, advancing maternal age and parity, cigarette smoking, multiple gestation and male fetal gender. Condi- tions associated with placenta previa include placenta accreta, vela- mentous umbilical cord insertion, vasa previa and abnormal fetal lie. Placenta accreta occurs when the placenta traverses the decidua and invades the myometrium. Velamentous insertion of the umbilical cord occurs when the fetal blood vessels do not insert on the disc of the placenta, presumably as a result of abnormal placental migration. Vasa previa is a rare condition in which the umbilical blood vessels insert onto the fetal membranes instead of the placenta and a fetal vessel lies over the internal os of the cervix. Placenta previa is thought to occur when an embryo fails to implant in the upper segment of the uterus. Reasons for the abnormal implanta- tion include scarring of the uterus from cesarean deliveries, uterine curettage and prior pregnancies, a need for increased placental surface area to compensate for a reduction in uteroplacental nutrient or oxygen delivery such as occurs with maternal smoking or multiple gestation, and delayed implantation associated with later fertilization in male embryos. An abnormal fetal lie may result from the large volume of placenta in the lower portion of the uterine cavity with a placenta previa. Abnormal fetal lie and presentation The term "lie" refers to the orientation of the fetus in the uterus. By far the most common fetal lie is longitudinal. Transverse lie means the fetus is lying sideways in the uterus. Occasionally, the fetal and maternal axes will cross at a 45° angle, forming an oblique lie. Oblique lies are unstable and will usually convert to a longitudinal lie in labor. Only longitudinal lies can safely be delivered vaginally. Presentation refers to the fetal part that is in closest proximity to the birth canal. The most common fetal presentation is head-down (cephalic or vertex); 95% of fetuses are vertex at term. The second most common presentation is breech, in which the fetal legs or but- tocks are just above the cervix. A shoulder typically presents when the fetus is lying transverse. The major risk factor for abnormal fetal lie and presentation is prematurity. Other risk factors include fetal malformations, congenital neuromuscular disorders, multiple gestation, uterine malformations and high maternal parity (number of prior births).

ReproGen

Chromosomes Human chromosomes are complex structures consisting of deoxyribo- nucleic acid (DNA), ribonucleic acid (RNA) and protein. Each single helix of DNA is bound at each end with a telomere and has a centro- mere somewhere along the length of the chromosome. The telomere protects the ends of the chromosome during DNA replication. Tel- omere shortening is associated with aging. The centromere is the site at which the mitotic spindle will attach and is necessary for proper segregation of chromosomes during cell division. The centromere divides the chromosome into two arms, identi ed as p (petit) for the short arm and q for the long arm. The centromere can be positioned anywhere along the arm of the chromosome and its location has been used to group like chromosomes together as central (metacentric), distal (acrocentric) or others (submetacentric). The length of the chro- mosome plus the position of its centromere are used to identify indi- vidual chromosomes within the 22 pairs of autosomes and one pair of sex chromosomes. Chromosomes are numbered in descending order of size; 1 is the largest. The only exception to this rule is chromosomes 21 and 22; 22 is larger than 21. Because of the historical convention of associating Down syndrome with trisomy 21, this chromosome pair was not renamed when the size difference became apparent. A karyotype is a display of chromosomes ordered from 1 to 22 plus the sex chromosomes, with each chromosome oriented so that the p arm is on top. Females have a 46XX karyotype and males a 46XY karyotype (Fig. 4.1a and b). Mitosis and meiosis These are two distinct types of cell divisions, with several common features. The rst is the need to duplicate the entire chromosome content of the cell prior to division. Both also use the cell machinery of the parent cell to make the DNA, RNA and new proteins that will participate in the cell division. Finally, both processes rely on using the mitotic spindle to separate the chromosomes into the two poles of the cell that are destined to become the progeny of that cell. Mitosis and meiosis differ in that duplicated chromosomes behave differently after DNA replication (Fig. 4.2). In mitosis, there is no difference in total chromosome content between parent and daughter cells; in meiosis, the chromosome number of the daughter cells is eventually reduced from 46 to 23, which is necessary to convert the diploid germ cell precursors originating in the embryo into haploid (1n) germ cells. These haploid germ cells will produce a new diploid organism at fertilization. Meiosis promotes exchange of genetic material through chromatid crossing over; mitosis does not. During the interphase preceding cell division, the DNA for each chromosome is duplicated to 4n. Thus, each chromosome consists of two identical chromatids joined at the centromere. In mitosis, the chromosomes rst shorten and thicken and the nucle- oli and nuclear membrane break down (prophase). During met- aphase, a mitotic spindle forms between the two centrioles of the cell and all chromosomes line up on its equator. The centromere of each chromosome splits and one chromatid from each chromosome migrates to the polar ends of the mitotic spindle (anaphase). In telophase, new nucleoli and nuclear membranes form, the parent cell divides into two daughter cells and the mitotic spindle is disassembled. Two genetically identical cells now exist in place of the parent cell. Mitosis is a non- sexual or vegetative form of reproduction. Meiosis involves two sequential cell divisions, again beginning with the 4n DNA produced in interphase. In prophase of the rst division (prophase 1), several speci c and recognizable events occur. In the leptotene stage, the chromosomes become barely visible as long thin structures. Homologous pairs of chromosomes then come to lie side by side along parts of their length, forming tetrads (zygotene stage). The chromosomes thicken and shorten, much as they do in mitotic prophase (pachytene stage); however, the pairing that occurred in the zygotene stage allows synapsis, crossing-over and chromatid exchange to happen. In the diplotene/diakinesis stage, the chromo- somes shorten even more. The paired homologous chromosomes show evidence of the crossing-over and chromatid exchange, displaying characteristic chiasmata that join the chromosome arms. Loops and unusual shapes within the chromosomes may be apparent at this stage. In metaphase 1 of meiosis, the nuclear membrane breaks down and the joined pairs of homologous chromosomes line up at the equator of the spindle apparatus. One of each pair of homologous chromo- somes then moves to each end of the cell along the spindle (anaphase 1). Nuclear membranes may then form, yielding two haploid daughter cells with 23 2n chromosomes in telophase 1. In the second meiotic division, these haploid cells divide as if in mitosis. This second divi- sion produces four haploid cells each containing 23 1n chromosomes. Unlike the cells produced in mitosis, these daughter germ cells are genetically unique and different from the parent cells because of the genetic exchanges that took place in the diplotene stage. Haploid germ cells participate in sexual reproduction in which a sperm cell and oocyte come together to form a new diploid zygote. While the sequence of events in meiosis during spermatogenesis and oogenesis is basically the same, there are several important differences. In the prepubertal male, primordial germ cells are arrested in interphase. At puberty, these cells are reactivated to enter rounds of mitoses in the basal compartment of the seminiferous tubule. These reactivated cells are known as spermatogonial stem cells. From this reservoir of stem cells, early spermatogonia emerge and divide several times again to produce a "clone" of spermatogonia with identical genotypes. All the spermatogonia from the clone then enter meiosis 1 and 2 to produce unique haploid sperm. New stem cells are constantly entering the spermatogenic cycle (Chapter 8) and thus the sperm supply is constantly renewing itself. Because of the relatively short time for spermatocytes to progress through meiosis and because of the tremendous competition among spermatozoa to reach the single oocyte within the female tract, fertilization of an egg by an aneu- ploid sperm is far rarer than the converse. In contrast to the testis, the ovary of a female at birth contains all the germ cells it will ever have. These oocytes remain arrested in prophase 1 of meiosis until the LH surge at ovulation initiates met- aphase 1. Thus, the duplicated genetic material within the oocyte exists paired with its homologous chromosome for 10-50 years before the cell is called upon to divide. For this reason alone, oocytes are much more prone to chromosome abnormalities than are sperm. Non-disjunction This is the failure of a chromosome pair to separate during meiosis, and can occur at either meiosis 1 or 2. When a single chromosome is involved, the aneuploid zygote is either monosomic or trisomic for the chromosome pair that failed to divide properly. With the exception of monosomy X or Turner syndrome, monosomic embryos are uni- formly miscarried (Chapter 36). Most trisomic fetuses are also miscar- ried; only three (trisomy 13, 18 and 21) are reported among live births. Those that survive to birth are likely mosaics that carry nonaffected cell lineages. If all the chromosomes are present in multiples other than 2n, the embryo or fetus is polyploid. Imprinting Although it is critical that the zygote has 2n chromosomes, it is also important that one set of chromosomes comes from each parent. Dermoid cysts and hydatidiform moles (gestational trophoblastic disease; Chapter 45) each have all 46 chromosomes from a single parent. Cytogenetic studies of these entities have shown the impor- tance of imprinting in early embryonic development. Imprinting is the process by which speci c genes are methylated so that they can no longer be transcribed. Normal embryonic development requires that one set of genes be maternally imprinted and a second paternally. Otherwise, important steps in development will not occur and the zygote cannot form normally. For instance, two sets of maternally imprinted genes are present in dermoid tumors of the ovary, resulting in development of disorganized fetal tissues without any supporting placenta or fetal membranes. Conversely, two sets of paternally imprinted genes are present in hydatidiform moles. In these cases, dysplastic trophoblast develops, but a fetus does not.

Ch 23 The Breast and Lactation

Development of the breast The human mammary gland is derived from ectoderm. It is rst visible in the 4-week embryo as a bud or nodule of epithelial tissue appearing along a line known as the milk crest. In the more developed embryo, this crest extends from the midaxilla to the inguinal region and may be the site of supernumerary breasts or nipples in the adult. The rudi- mentary epithelial nodule rst becomes buried in embryonic mesen- chyme, where it undergoes further differentiation, apparently under the in uence of paracrine signals from the mesenchyme. Secondary epithelial buds form cellular cords that elongate, bifurcate and cavitate. These cords become the excretory and lactiferous ducts of the mammary gland. The human mammary gland is a compound tuboalveolar structure composed of 15-25 irregular lobes radiating out from the nipple (Fig. 23.1). Individual lobes are embedded in adipose tissue and separated by dense layers of connective tissue. Each lobe is further subdivided into lobules, connected to the nipple by lactiferous ducts. The lactifer- ous ducts are lined by a strati ed squamous epithelium. Loose con- nective tissue (stroma) surrounds the lactiferous ducts and permits their ready distension during lactation. At birth, the breast is rudimentary and consists almost entirely of primitive lactiferous ducts. Although it may secrete a few drops of milk, called "witch's milk," this secretory function is short-lived and the breast quickly becomes quiescent until puberty. At puberty, ovarian estrogens stimulate the lactiferous duct system to grow. After menarche, exposure to cyclic progesterone induces further ductal growth and development of rudimentary lobules at the ends of the ducts. The breasts continue to grow for several years after menarche as the lac- tiferous ducts progressively subdivide, elongate and hollow out, and adipose tissue accumulates. However, complete lobular development and maturation will not occur in the absence of pregnancy. At the beginning of pregnancy there is rapid growth and branching of the terminal portions of the rudimentary lobules under the in uence of chorionic gondotropin. Vascularity increases dramatically. The pregnant woman often perceives these two changes as a "tingling" or "tension" in her breasts. This sensation begins shortly after conception and may last throughout the rst trimester. At about 8 menstrual weeks of pregnancy, sustained progesterone exposures initiates complete alveolar differentiation. True glandular acini appear as hollow alveoli lined with a single layer of myoepithelial cells. The highly branched myoepithelial cells form a loose network surrounding the alveoli. The alveoli connect to the larger lactiferous ducts through intralobular ducts. Alveolar secretion begins in the second trimester of pregnancy. By the third trimester, an immunoglobulin-rich secretion is seen dis- tending the alveoli. While the role of ovarian steroids in breast development is clearly clinically established (prepubertal gonadal failure is associated with absence of breast development), animal models suggest that other hormones may also be involved in human breast development. Insulin exposure causes multiplication of epithelial cells and formation of lobuloalveolar architecture. Complete cytologic and functional dif- ferentiation of the epithelial cells lining the alveoli requires exposure to cortisol, insulin and prolactin. Receptors for growth factors such as insulin-like growth factor 1 (IGF-1) and epidermal growth factor (EGF) have been demonstrated on human mammary cells, suggesting an important role for their ligands in breast development and function. Milk formation Milk has more than 100 constituents. It is basically an emulsion of fat in a liquid phase that is isotonic with plasma. Mature human milk contains 3-5% fat, 1% protein, 7% lactose and 0.2% minerals, and delivers 60-75kcal/dL. The principal class of human milk lipids is triglycerides. The main proteins in human milk are casein, α-lactalbumin, lactoferrin, immunoglobulin A, lysozyme and albumin. Casein and α-lactalbumin are speci c milk proteins; α-lactalbumin is part of the enzyme complex lactose synthetase. Lactose is the primary sugar in human milk. Free amino acids, urea, creatinine and creatine are also present. Minerals include sodium, potassium, calcium, mag- nesium, phosphorus and chloride. As the composition of human breast milk continues to be studied, several peptide hormones, including EGF, transforming growth factor α (TGF-α), somatostatin and IGF-1 and IGF-2 have also been identi ed. The rst milk secreted after delivery is called colostrum. It contains a higher protein content (largely immunoglobulins) and lower sugar content than subsequent secretions. The alveolar epithelial cells that make milk are polarized, highly differentiated cells whose function is to accumulate, synthesize, package and export the components of milk. At least four transcel- lular pathways are required for appropriate milk formation within the alveolus of the breast. The rst involves secretion of monovalent cations and water. Water is drawn across the alveolar cell by a con- centration gradient generated by speci c milk sugars; ions follow an electrochemical gradient. The second involves receptor-mediated transport of immunoglobulins. Immunoglobulin A (IgA) enters the epithelial cell after binding to its receptor, becomes internalized and is transported either to the Golgi apparatus or the apical membrane of the cell for secretion. The third pathway involves the synthesis and transport of milk lipids, which are synthesized in the cytoplasm and smooth endoplasmic reticulum. They then aggregate into droplets that coalesce to form larger fat globules. These are discharged from the apical part of the cell into the alveolar lumen. The nal pathway involves exocytosis of secretory vesicles containing speci c milk proteins, calcium, phosphate, citrate and lactose. These vesicles form in the Golgi apparatus. Here, casein, the speci c milk protein, forms micelles with calcium and phosphate. The Golgi is impermeable to lactose. Because lactose is an osmotically active sugar, water is drawn into the Golgi and lactose content thereby determines the milk's liquid volume. A fth pathway is required for milk formation: it is not transcellular, but paracellular. Immunoglobulins, such as IgA, plasma proteins and leukocytes can move between alveolar cells that have lost their tight junctions. Regulation of milk production Regulation of the quantity and content of breast milk is largely under hormonal control, with prolactin being the most important regulatory hormone in humans, although its actions require synergism with several others. Prolactin concentrations in the plasma rise steadily throughout pregnancy, from less than 20 ng/mL to over 200 ng/mL at term (Chapter 18). In breastfeeding women, basal serum prolactin levels remain elevated for about 4-6 weeks postpartum, then fall to nonpregnant levels despite continued lactation. For about the next 2 months, suckling causes spikes of prolactin release. Even with produc- tion of a litre or more of breast milk per day, this re ex is also gradu- ally lost. The pivotal role of prolactin in the initiation of breastfeeding was established by blocking secretion of the hormone from the pituitary using the dopamine agonist, bromocriptine. When bromocriptine is given to women shortly after delivery, prolactin levels drop precipi- tously to nonpregnant levels. Breast engorgement and lactation never occur. Estrogens can also be used to suppress lactation immediately postpartum, but they work through a different mechanism. After estro- gen administration, prolactin levels remain quite elevated, but no milk is formed. Thus, estrogens inhibit the action of prolactin on the breast, which is probably why lactation does not occur before delivery. With delivery of the placenta, the source of the large amount of circulating estrogen is removed. Circulating estrogens drop precipitously and breast milk begins to form within 24-48h. Bromocriptine adminis- tered later in the postpartum period also inhibits lactation, but only until the process no longer depends on prolactin. Prolactin has several actions at the cellular level. It stimulates the synthesis of α-lactoglobulin and casein in breast tissue primed by insulin and cortisol. It stabilizes casein mRNA, prolonging its half-life eightfold. Prolactin stimulates milk fat synthesis and may be involved in sodium transport in mammary tissue. Interestingly, and unlike other polypeptide hormones, prolactin binding to its receptor does not stimu- late adenylate cyclase activity. The lactation re ex Although prolactin is responsible for initiating milk production, milk delivery to the infant and lactation maintenance depend on mechanical stimulation of the nipple. The suckling stimulus is known as milk ejection or letdown. Although suckling is the major stimulus for milk letdown, the re ex can be conditioned. The cry or sight of an infant and preparation of the breast for nursing may cause letdown, while pain, embarrassment and alcohol can inhibit it. The suckling re ex is initiated when sensory impulses originating in the nipple enter the spinal cord through its dorsal roots. A multisy- naptic neural pathway ascends to the magnocellular supraoptic and paraventricular nuclei of the hypothalamus via activin-containing neurons in the nucleus solitarius tract. Impulse recognition results in episodic oxytocin release from the posterior pituitary. Oxytocin then stimulates the myoepithelial cells lining the milk ducts to contract, thereby causing milk "ejection." A large surge in prolactin release is temporally associated with the episodic oxytocin release induced by nursing, but this surge will occur independently of the oxytocin changes. This transient pulse of prolac- tin induces milk formation for the next feeding. Smoking can inhibit this prolactin surge and cause a decrease in milk production. The suckling re ex also affects the activity of the gonadotropin- releasing hormone (GnRH) pulse generator. Suckling inhibits gonado- tropin release and ovulation does not typically occur. The effectiveness of lactation in suppressing gonadal function is directly related to the frequency and duration of nursing. Among the !Kung hunter-gatherers in Africa, the average interval between births is 44 months in spite of early postpartum resumption of coitus and lack of contraception. Mothers nurse about every 15 minutes and children are in immediate proximity to their mothers all day and night for 2 years or more.

Spontaneous Loss

Ectopic pregnancy Any pregnancy that implants outside of the uterine endometrial cavity is called an ectopic pregnancy. Despite improved diagnostic and thera- peutic approaches to this disorder, ectopic pregnancy remains the most common cause of pregnancy-related maternal death in the rst 12 weeks of pregnancy. A ruptured ectopic preganacy is a medical emergency. Overall, ectopic pregnancies cause 4-10% of pregnancy-related deaths with maternal hemorrhage the ultimate fatal pathway. The incidence of ectopic pregnancy rose in the USA from the 1950s through the 1990s when national recording was halted. At that time the best estimate for the incidence of ectopic pregnancy was 2 in 100 pregnancies. The known risk factors for ectopic pregnancy focus on alterations in appropriate function of the fallopian tube. The fallopian tube is not simply a conduit for sperm and embryo passage but rather a delicate microenvironment in which cilia help to move the uids within the fallopian tubes that transport gametes and blastocysts. Decreased ciliary movement due to exposure to elevated levels of progesterone or direct damage, ciliary and cellular destruction as the result of trauma or infectious disease, and tubal blockage from surgical interruption or scarring all promote abnormal embryo transport. Over 90% of ectopic pregnancies can be directly related to tubal pathologies. From highest to lowest risk, these include: (i) previous ectopic pregnancy; (ii) tubal sterilization or reconstructive surgery; (iii) in utero exposure to diethyl stilbesterol (DES); (iv) prior genital tract infection (often silent, par- ticularly with chlamydia); (v) infertility; (vi) multiple sexual partners; (vii) cigarette smoking; (viii) young age at initiation of sexual activity; (ix) maternal age at conception of >35 years; and (x) the practice of vaginal douching. The remaining 10% of ectopic pregnancies are of unknown etiology. They may result from embryonic factors, although there is no increase in embryonic or fetal karyotypic abnormalities when ectopic gestations are compared with intrauterine gestations. Two commonly cited risk factors for ectopic pregnancy are frequently misinterpreted. The use of assisted reproductive techniques, including in vitro fertilization, has recently been shown to have little effect on the overall incidence of ectopic pregnancies, although the rate of the otherwise rare heterotopic pregnancy (an ectopic gestation coexisting with an intrauterine gestation) is increased. The use of an intrauterine contraceptice device (IUD) protects against all pregnancies and thereby decreases the overall ectopic pregnancy rate. However, when pregnancy does occur with an IUD in place, the gestation is more likely to be ectopic. Almost all ectopic pregnancies (∼95%) occur in the fallopian tube (Fig. 36.1). The most common site of implantation of an ectopic gesta- tion within the fallopian tube is in its ampullary portion. Ampullary and mbrial ectopic gestations frequently dislodge and abort prior to rupture. As the interstitial portion of the fallopian tube has thick mus- cular support, interstitial ectopic gestations may develop to relatively late gestational ages prior to clinical presentation. Cervical, interstitial and heterotopic (intrauterine + ectopic) ectopic pregnancies are rare but appear to be more frequent after in vitro fertilization. Ovarian ectopic gestations are random events without documented risk factors. Abdominal ectopic pregnancies are exceedingly uncommon. Miscarriage A miscarriage is de ned as a spontaneous pregnancy loss before 20 weeks' gestation; the medical term is spontaneous abortion. Miscarriages occur in 15% of clinically recognized pregnancies. The total number of human conceptions far exceeds the number of births. It is estimated that at least 60% of all human conceptions do not result in a viable pregnancy, with the majority of these being spontaneously lost before or shortly after an expected menses. These pregnancies can be documented by the appearance and disappearance of a pregnancy- speci c hormone (human chorionic gonadotropin, hCG; Chapter 18) from the maternal bloodstream. It is clear that there is a sensitive and effective mechanism in the maternal system that can detect abnormal pregnancies and prevent survival of the overwhelming majority. It is impossible to know the causes of those pregnancy losses that occur around the time of the expected menses, the so-called biochemi- cal pregnancies. They probably result from a myriad of abnormalities and pregnancy loss represents the nal common clinical outcome. Abnormalities may occur in the conceptus or in the microenvironment of the maternal reproductive tract at the time of conception. The latter may result from congenital or acquired anatomic defects in the uterus. They may also be caused by endocrine abnormalities that alter the maturation of the ova prior to ovulation, the development of the embryo during transit to the intrauterine cavity or the growth and maturation of the endometrium as it prepares for implantation. It is known that the most frequent cause of overt miscarriage is a chromosomal abnormality in the conceptus. At least 60% of miscar- riages have a gross chromosomal abnormality that can be detected in the expelled fetal material. Table 36.1 lists the frequency of speci c chromosomal abnormalities in miscarried material. It is usually not possible to identify a speci c etiology for the remaining 40% of isolated spontaneous pregnancy losses, although some are the result of an under- lying problem that can lead to recurrent pregnancy losses. Increasing maternal age is accompanied by an increase in the fre- quency of chromosomal abnormalities in embryos and fetuses and in the rate of spontaneous pregnancy loss. Age-related egg abnormalities are thought to account for the majority of this effect, consistent with the dramatic rise in spontaneous pregnancy loss that is seen among mothers who are 35 or older. This effect is not noted in association with paternal age until the father of the pregnancy has reached at least 55 or 60 years. Even then, the effect is more subtle. Interestingly, an increase in the frequency of certain psychiatric disorders among off- spring is associated with paternal aging. Ovum deterioration is thought to explain most of the decline in fertility after the maternal age of 40. Most spontaneous pregnancy losses are heralded by vaginal bleed- ing and a fall in maternal serum hCG during the rst trimester of preg- nancy. These losses are subcategorized by clinical presentation as outlined in Table 36.2. During the rst 12 weeks of pregnancy, maternal serum hCG normally rises with a doubling time of about 48-72 h. The hCG level will typically plateau or drop before tissue is passed in pregnancies with threatened miscarriages. Thus, it would appear that the common signaling mechanism for abnormal pregnancies may be a disruption in the expres- sion of the hCG gene located on chromosome 19. How trisomies and other chromosomal aneuploidies produce this effect on the hCG gene is not known. Moreover, fetuses with trisomy 13, trisomy 18 and trisomy 21 (Down syndrome) can be carried to viability. It is equally puzzling how these three trisomies escape the hCG signaling surveillance. Trisomy 21 is actually associated with an increase in circulating hCG in the second trimester. This nding is used during the rst trimester of pregnancy in serum screening regimens that determine Down syndrome risk. Recurrent pregnancy loss Because one in every six pregnancies will result in a miscarriage, it is not uncommon for a woman to experience one or more spontaneous losses during her pregnancy attempts. A woman who has had two con- secutive spontaneous losses, but has never carried a pregnancy to full term, has a 35% chance of a loss in her next pregnancy. If a woman has successfully carried a pregnancy in the past, she will not reach a similar level of risk for spontaneous loss in a subsequent pregnancy until she has experienced three losses. For this reason, diagnostic work-up should be initiated in women with two losses if no successful pregnancies have occurred in the past. Clinicians may choose to wait until a third loss in patients who have had successful pregnancies. It is reasonable to con- sider initiating diagnostic testing at an earlier point in the clinical history among women with infertility or advanced maternal age. Causes of recurrent pregnancy loss (recurrent miscarriage) include parental chromosome translocations; structural uterine abnormalities such as longitudinal septa and intrauterine adhesions; endocrine disor- ders, including luteal phase defects, polycystic ovary syndrome (PCOS), hyperprolactinemia, thyroid dysfunction and poorly controlled diabetes mellitus; autoimmune conditions such as the antiphospholipid antibody syndrome and a variety of heritable thrombophilias. Couples experienc- ing recurrent pregnancy losses are appropriately anxious and should be evaluated for an underlying cause in the hope that a speci c intervention may prevent future spontaneous pregnancy losses. Stillbirth The term stillbirth is synonymous with fetal death or demise. All three terms refer to the delivery of a fetus after 20 menstrual weeks that shows no signs of life. Stillbirth rates vary widely between devel- oped countries where the overall rate is 6-7 in 1000 births and devel- oping countries where the rate may be as high as 30 in 1000 births. Similarly, the etiologies vary by environment and resources; in devel- oped countries fetal growth restriction, congenital or karyotypic anom- alies, and maternal medical diseases account for many stillbirths whereas pre-eclampsia, obstructed labor and infection are more common causes in less developed countries. Fetal death before the onset of labor (antepartum fetal death) is much more common than fetal death during labor or delivery (intrapartum fetal death). There are many causes of stillbirth. An etiology is never identi ed in at least 25% of stillbirths (unexplained stillbirth) even after com- plete evaluation. Fetal causes for stillbirth include chromosomal and genetic abnormalities and congenital malformations. Placental causes include premature separation before delivery (abruption), hemorrhage from the fetus into the maternal circulation (fetomaternal hemorrhage) and umbilical cord complications. Other causes such as intrauterine infection and fetal growth restriction are multifactoral, often involving the mother and either placenta or fetus.

47 Sexually transmitted diseases of viral origin

Human papillomavirus Although rare, it is possible to acquire HPV through nonsexual transmission. Neonates can become infected during delivery. Biology of human papillomaviruses HPV is a member of the Papovaviridae family of DNA viruses. Other well-known members of this family are the polyomaviruses (polio virus and SV40). Of the 130 different HPV genotypes identi ed to date, about 40 are associated with genital lesions. Types 6 and 11 are most commonly identi ed in genital warts, and types 16 and 18 are most closely associated with neoplasia (high-risk subtypes). HPV sub- types 1-5 are associated with common skin warts and plantar warts. The success of HPV as an infectious agent is directly linked to a virus replication cycle that effectively evades immunologic detection by the host. The virus infects primitive keratinocytes in the basal layers of squamous epithelia followed by a round of viral DNA replication that appears independent of the host cell cycle (Fig. 47.1). Once the infected keratinocyte enters the proliferative compartment of the epi- thelium, viral gene expression is minimal. The oncogenes E6 and E7 are highly repressed by the viral genes E1 and E2 until the infected keratinocyte exits the cell cycle and enters the uppermost differentiat- ing compartment (Table 47.1). Thus, high levels of viral protein syn- thesis and assembly only occur in the upper layers of the squamous epithelium. In this infectious cycle, the virus hitches a ride in the keratinocyte at the beginning of its journey and replicates in cells that will terminally differentiate and die by natural causes. Thus, there is no viral-induced cytolysis, necrosis or in ammation. Because there is no blood-borne phase of the HPV life cycle and only minimal amounts of replicating virus are exposed to immune defense, the virus is essen- tially invisible to the host. It is only when host integration occurs with E1 and E2 disruption, that E6 and E7 are overexpressed. E6 and E7 are capable of interfering with important tumor suppressor proteins in the host cell. Their overexpression is associated with neoplastic trans- formation, explaining the oncogenic potential of HPV. HPV vaccines are effective because they circumvent the viral epi- thelial evasion strategies by introducing virus antigens through an intramuscular route. An immune cascade resulting in a robust T-cell- dependent B-cell response generates high levels of L1 speci c neutral- izing antibodies and immune memory. Infection with the human papillomavirus (HPV) is the most common sexually transmitted infection (STI) in the world. HPV is a wily pathogen that causes a spectrum of clinical diseases, all of which involve cutaneous or mucosal squamous surfaces. From the evolutionary standpoint, HPVs are very successful infectious agents because they induce chronic infections that have no systemic sequelae and rarely kill the host. Instead they periodically shed large amounts of infectious virus for transmission to naïve individuals. The broad spectrum of genital HPV infection includes: (i) latent infection; (ii) clinically apparent lesions (condylomata accuminata, warts); and (iii) HPV-associated neoplasia. Latent infections are iden- ti ed by the presence of HPV DNA in tissue samples acquired for epidemiologic study. In the absence of tissue collection, latent infec- tions would go unrecognized because neither microscopic nor visible lesions are present. Overt genital warts, also known as condyloma acuminata, are esh-colored, pink or pigmented papules with a frond- like surface. Sessile warts, or at condyloma-like lesions, are less common, accounting for only 20% of visible genital warts. Most genital warts in men are on the penis. In women, they are found most often at the vaginal introitus and on the labia. Most genital warts are asymptomatic. When symptoms do occur, they are often secondary to local friction-induced irritation from clothing or intercourse. HPV- associated neoplasias include intraepithelial lesions of the cervix (CIN) and vulva (VIN) and invasive carcinomas at both sites. Cervical cancer is discussed in detail in Chapter 44. Because most genital warts are sexually transmitted, their presence indicates risk for other STIs. Treatment of genital warts involves cryo- therapy or topical application of agents that cause cytolysis. Epidemiology of HPV The primary risk factor for HPV infection is sexual activity. It is esti- mated that 75% of sexually active women will acquire latent HPV infection. Fortunately, most HPV infections are transient; up to 90% of infections in women will resolve spontaneously within 2 years of acquisition. Unfortunately, persistent infection is more common with HPV genotypes that have neoplastic potential. Herpes simplex virus Genital herpes is an STD that does not go away. Instead, the respon- sible agent, herpes simplex virus (HSV), establishes latent genital infection in the sacral dorsal root ganglia. It can be reactivated from latency by fever, sun exposure and hormonal changes. Herpetic infec- tion causes the greatest morbidity in the neonate, who acquires it from the genital tract of the mother at delivery, and in immunocompromised patients for whom its disseminated form can be life-threatening. There are two distinct serological types of HSV: HSV-1 and HSV-2. HSV-1 infection is typically asymptomatic and nearly ubiquitous. It is transmitted by primary infection of the respiratory tract. HSV-1 has been found in the trigeminal ganglion of 80% of cadavers. HSV-2 has a predilection for genital disease, although HSV-1 infec- tions of the genitalia and HSV-2 infections of the oral cavity do occur. HSV-2 is much more likely than HSV-1 to become a latent infection of the sacral ganglion and to cause neonatal disease. Patients with herpetic infections present with three clinical sce- narios: primary rst episode, nonprimary rst episode and recur- rent episodes. These presentations inform our understanding of the biology and epidemiology of genital HSV infections. First episodes describe the initial recognition by the patient or health-care provider that a genital herpes infection is occurring. In primary rst episodes, no HSV antibodies can be detected in acute phase serum samples, demonstrating that there has been no prior HSV infection. HSV anti- bodies will be present at the time of the rst recognized genital herpes outbreak in nonprimary rst episodes. Recurrent episodes require rec- ognition that the patient has had a prior episode(s) of symptomatic HSV. The severity of clinical manifestations and the incidence of complications at presentation vary according to whether the infection is primary, nonprimary or recurrent. Primary genital HSV disease is typically the most severe although it can be totally asymptomatic. Over 80% of patients with primary genital HSV will have local painful penile or vulvar lesions, dysuria, urethral or vaginal discharge and painful inguinal adenopathy. The mean duration of viral shedding from mucocutaneous lesions in primary genital HSV-2 infections is 2-3 weeks. Nonprimary rst infections tend to be milder than primary rst infections, presumably because acquired humoral and cellular immunity partially contain infectious spread. Recurrent genital HSV-2 disease typically involves painful recru- descence of the mucocutaneous lesions on the penis or vulva and cervix. Local viral shedding occurs at the site of lesions, although cervical shedding has also been documented in the absence of visible cervical lesions. Systemic symptoms are absent. The mean duration of symptoms and viral shedding is much shorter with recurrences. Medications that inhibit viral DNA synthesis have been developed to treat the symptoms of HSV infection. Treatment will stop viral DNA replication and spread but will neither prevent latent infections nor eradicate the virus. Abstinence from sexual contact with an infected partner when lesions are visible is the only way to prevent genital HSV infection. Unfortunately, even this is not completely protective because trans- mission can occur during asymptomatic viral shedding. Condoms are also not completely protective. The penile shaft may be partially exposed to the vulva during intercourse using a condom. In addition, HSV is capable of penetrating latex. Epidemiology of genital HSV infection Symptomatic genital HSV infection accounts for 2-4% of visits to STD clinics in the UK and the USA. Genital HSV infections are reported more commonly among Caucasians than non-Caucasians. A higher prevalence of anti-HSV antibodies is noted with decreasing age at rst coitus and with increasing number of sexual partners. The incidence of neonatal herpes is about 1 in 7500 live births. Biology of HSV HSV is a member of the herpesvirus class of DNA viruses. Herpes- viridae include the two serotypes of HSV, cytomegalovirus (CMV), varicella zoster (chickenpox, shingles) and Epstein-Barr virus (mono- nucleosis, chronic fatigue syndrome). Herpesviruses would be better called "complex" rather than "simplex" because they have the most complicated structure and replication cycles of all the viruses. Genital HSV is acquired by sexual contact with contaminated secre- tions or lesions. Herpesviruses are very susceptible to desiccation and extremes of temperature, making transmission by fomites very rare. Once the virus has gained access to mucosal cells, it destroys the host DNA during productive replication of its own and kills the cell. HSV spreads by contiguity to adjacent cells and tracks toward autonomic nerve endings. Mucosal and skin cells infected with HSV produce serous transudates that result in the classic vesicles seen in the disorder. Following primary genital mucocutaneous infection, HSV virions travel to the dorsal root ganglia of the sacral plexus (S2-S4) via the intra-axonal route. Here, they persist in a nonreplicative state until reactivation. Reactivation is heralded by a dramatic increase in viral DNA synthesis. This is followed by spread of virus back down the sensory neurons to the skin. HSV in pregnancy and the neonate Ninety per cent of women with primary genital HSV-2 infection shed virus from their cervix during the acute infection. This level drops to 70% both in women with primary genital HSV-1 infection and in women with nonprimary rst episodes of genital HSV-2 infection. These numbers stand in stark contrast to the 12-20% rate of cervical shedding among women with recurrent external genital lesions. There- fore, it is not surprising that 50% of pregnant women with primary genital HSV will transmit infection to the neonate while only 5% of women with recurrent genital HSV will do so. Neonatal herpetic infec- tions are life-threatening. They may be prevented with appropriate use of cesarean delivery.

Ch 32 Prolactinemia

Hyperprolactinemia is a common clinical problem. Cases resulting from inappropriate prolactin secretion by the pituitary gland are the third most frequently diagnosed cause of chronic anovulation and secondary amenorrhea. There are many etiologies for this condition; some result from serious underlying pathology and others from revers- ible functional disorders. Control of prolactin secretion is dominated by tonic inhibition and there is no regulation by classic negative feedback from its target organs. These characteristics are unique among pituitary hormones. The major inhibitor of prolactin secretion is dopamine and the two major stimuli are estrogen and thyrotropin-releasing hormone (TRH). Numer- ous other neurohormonal regulators must also be considered when elucidating the mechanisms by which hyperprolactinemia develops. Regulation of prolactin secretion Embryonic differentiation of the lactotroph is under the control of the pituitary-speci c transcriptional factor Pit-1. While Pit-1 regulates prolactin gene transcription by binding directly to the prolactin pro- moter, other regulators of prolactin gene expression use alternative pathways (Fig. 32.1a). Dopamine released into the pituitary portal system binds to a G1-protein-coupled receptor and inhibits adenylate cyclase and phospholipase C. Acting as a neurohormone, rather than a neurotransmitter, dopamine reduces prolactin synthesis and prolactin release by the pituitary lactotrope. TRH acts through a second lac- totroph cell membrane receptor to activate phospholipase C. In con- trast to dopamine, TRH increases prolactin gene transcription and release of prolactin hormone from its storage granules. The effect of TRH is modulated by thyroid hormone such that decreases in T3 and T4 enhance prolactin release and increased concentrations of T3 and T4 decrease prolactin secretion. Estradiol acts through a third mecha- nism, binding not to a membrane receptor but to a nuclear receptor. The hormone receptor complex then interacts with estrogen response elements upstream of the prolactin gene. Estradiol also interferes with dopaminergic activation of its receptor and increases the concentration of TRH receptors on lactotrophs. Both actions potentiate the stimula- tory effects of the sex steroid. Like dopamine, γ-aminobutyric acid (GABA) and glucocorticoids inhibit prolactin secretion. The mechanism by which GABA acts as a prolactin inhibitory factor is unknown. Like estrogen, glucocorticoids act through nuclear receptors to inhibit prolactin gene transcription. Vasoactive peptide (VIP), oxytocin, angiotensin II (AgII) and serot- onin all increase prolactin secretion. VIP employs two mechanisms: it stimulates oxytocin release via the hypothalamus and it interferes with dopamine inhibition of adenylate cyclase. AgII acts on a speci c membrane receptor on the lactotroph to provoke rapid release of pre- synthesized prolactin. It is a more potent secretagogue for prolactin than TRH. Serotonin released by the dorsal raphe nucleus also stimu- lates prolactin release but not its synthesis. Here, serotonin activity occurs independent of dopamine pathways. In the physiologic state, ne tuning of prolactin secretion is deter- mined by the balance between the prolactin inhibitory factors (PIF) and the prolactin-releasing factors (PRF). Any disorder that alters the balanced secretion of these regulatory compounds will result in altered prolactin secretion. Regardless of its cause, hyperprolactinemia can interfere with hypothalamic-pituitary function and result in hypogo- nadism with or without galactorrhea. The fact that women with prolactin-induced amenorrhea are hypo-estrogenic but do not experi- ence hot ashes suggests that one mechanism by which prolactin alters hypothalamic-pituitary function is via modulation of central neuro- transmission. The hypothalamic dopaminergic and opioid systems that regulate gonadotropin-releasing hormone (GnRH) pulsatility are likely to be involved in this effect. Physiologic hyperprolactinemia Most physiologic hyperprolactinemia is transient and of no clinical con- sequence. High physiologic concentrations of plasma prolactin occur at night and result from both an intrinsic circadian rhythm and sleep- entrained prolactin release. High protein meals at midday, but not in the morning, induce prolactin release through an unknown mechanism. Physical and emotional stress, including exercise, hypoglycemia and anesthesia are associated with elevations in prolactin secretion. Orgasm promotes prolactin secretion, but only in women. Pregnancy is associated with a marked elevation of prolactin secretion that persists into the imme- diate postpartum period (Chapter 23). Of all the physiologic hyperprol- actinemic states, only lactation is associated with amenorrhea. Pharmacologic hyperprolactinemia Medications that interfere with dopaminergic inhibition of the pituitary lactotroph can cause hyperprolactinemia. Any drug that decreases the synthesis of dopamine, enhances its metabolism, increases its reuptake or interferes with its binding to its receptor will reduce the action of dopamine. When the inhibitory activity of dopamine on the pituitary lactotroph is blocked, prolactin secretion increases. All of the medications listed in Table 32.1 can inhibit dopamine action and cause hyperprolactinemia. Clinical manifestations of pharmacologic hyperprolactinemia include galactorrhea and menstrual irregularities. Menstrual dysfunction may be severe enough to result in amenorrhea. Pathologic hyperprolactinemia Lesions in the hypothalamus or in the pituitary gland can cause hyper- prolactinemia. Those in the hypothalamus typically do so by interfer- ing with dopamine delivery to the pituitary gland. Tumors are the most frequent of the pituitary causes of hyperprolactinemia; the prolactin-secreting adenoma is the most common of these (Fig. 32.1b). Prolactin-secreting adenomas (prolactinomas) are classi ed by size: microadenomas are less than 1 cm in size and macroadenomas are greater than 1 cm. These tumors can occur in both men and women, but are more common in women. In women they cause galactorrhea, amenorrhea, headache and visual eld defects. In men they cause headache, visual eld changes and impotence. They are often larger at diagnosis in men than in women because symptom onset is typically late in men. Prolactinomas are usually benign. Pituitary adenomas that produce adrenocorticotropic hormone (Cushing disease) and growth hormone (acromegaly) may also cause hyperprolactinemia. Primary hypothyroidism can also cause hyperprolactinemia. The decrease in circulating thyroid hormone that accompanies thyroid gland dysfunction diminishes negative feedback on the hypothalamus and pituitary gland. This results in an increase in TRH and thyroid-stimulating hormone secretion. Excessive TRH can override the normal dopamine- dominated inhibition of prolactin secretion through direct, receptor- mediated effects on the pituitary lactotroph. A signi cant proportion of patients with chronic renal failure will have hyperprolactinemia. While the etiology of this effect remains incompletely described, patients with chronic renal failure appear to have circulating serum factors that inter- fere with dopaminergic inhibition of prolactin synthesis and secretion. Treatment of hyperprolactinemia is directed toward correction of the underlying cause. A notable exception to this rule involves the management of the prolactin-secreting pituitary adenoma. Resection of these tumors is associated with a high frequency of recurrence of the hyperprolactinemia. Medical management is typically safer and more effective and involves use of oral dopamine agonists (e.g., bro- mocriptine, cabergoline). It is important to remember that men and women with hyperprolactinemia are hypogonadal due to the associ- ated abnormalities in the hypothalamic-pituitary-gonadal axis. This hypogonadal state places them at signi cant risk for osteoporosis (Chapter 24) and requires continuation of therapy for as long as the hyperprolactinemia persists. Galactorrhea Galactorrhea describes the secretion of breast milk in states unas- sociated with nursing. Galactorrhea can result from hyperprolactine- mia or from excessive sensitivity of the breast to normal circulating levels of prolactin. If galactorrhea is associated with amenorrhea, then hyperprolactinemia is likely the cause. If galactorrhea occurs in the presence of normal ovulatory cycles, then excessive sensitivity of the breast to normal circulating amounts of prolactin is more likely. The three most common causes of hyperprolactinemia resulting in galact- orrhea are: (i) a pituitary adenoma, (ii) medications interfering with dopamine action and (iii) hypothyroidism. Galactorrhea can be sup- pressed by the use of dopamine agonists.

Ch 34 Infertility

Infertility is de ned as a diminished capacity to conceive and bear a child. It is not equivalent to sterility, the absolute and irreversible inability to conceive. Clinically, a couple is considered infertile if they are unable to conceive after 12 months of unprotected, frequent coitus. Many factors contribute to infertility (Fig. 34.1). Diseases that affect only females account for about half of infertile couples and diseases that only affect males about one-third. About 10% of couples will have disorders in both the male and the female partner. Some 10-15% of couples have no identi able cause for their infertility or will become pregnant during the evaluation. Speci c disorders causing infertility include those involving each of the major physiologic events neces- sary to produce a pregnancy: (i) production of a healthy egg; (ii) production of healthy sperm; (iii) transportation of the sperm to the site of fertilization; (iv) transportation of the zygote to the uterus for implantation; (v) successful implantation in a receptive endometrium; (v) presence of other conditions, some immunologic, that can interfere with one or more of the other events. Oocyte abnormalities The main cause of female infertility due to oocyte abnormalities is a failure to ovulate regularly or, in some cases, at all. Those disorders that result in oligo-ovulation or anovulation are also causes of amenor- rhea (see Chapters 30 and 31), and fall into three categories: hypotha- lamic dysfunction, pituitary disease and ovarian dysfunction. Common hypothalamic causes of anovulation include abnormalities of weight and body composition, strenuous exercise, stress and travel. Pituitary or endocrine disorders associated with anovulation are hyper- prolactinemia and hypothyroidism. The two most common known causes of ovarian dysfunction are polycystic ovary syndrome and premature ovarian failure. Oocyte abnormalities more complex than simple anovulation cause the fairly rapid decline in fertility that occurs as women enter their 40s. Female anatomic abnormalities Fallopian tubal disease is usually the result of in ammatory scarring of the fallopian tubes. This may be caused by pelvic in ammatory disease, appendicitis with rupture, septic abortion, previous surgery and, occasionally, previous use of an intrauterine device. The most common site of tubal blockage is the distal mbriated end of the tube. These blockages are typically associated with additional pelvic adhe- sions and may affect up to 20% of the women in infertile couples. Purposeful, surgically-induced blockage occurs with surgical steriliza- tion; some women regret their contraceptive decision post-tubal steri- lization and present to the fertility specialist requesting reversal. Endometriosis is a common disorder, characterized by the presence of tissue resembling endometrium outside of its normal position lining the uterus. The glands and stroma of endometriosis are usually respon- sive to gonadal hormones and the biochemical changes the steroids induce in this ectopic endometrium mimic those seen in endometrium within the uterine cavity. Increased prostaglandin production by peri- menstrual and menstrual endometriotic lesions is thought to promote the in ammation, brosis and adhesion formation characteristic of the dis- order. Endometriosis lesions can be found almost anywhere in the pelvis but are most common on the peritoneal surfaces covering the pouch of Douglas, bladder, ovaries, fallopian tubes, bowel and appendix. Women with endometriosis can present with pelvic pain, adnexal masses (endometriomas), infertility, or any combination of these. Uterine leiomyomas, also known as broids or uterine myomas, are benign smooth muscle tumors of the uterus. They are the most common pelvic tumor in women, and may be located anywhere within the wall of the uterus or may hang from a stalk containing the blood supply to the tumour (pedunculated leiomyomas). Pedunculated leiomyomas may hang from the outside of the uterus or may project into the endometrial cavity. Those leiomyomas that distort the uterine cavity (submucosal in location) or physically obstruct fallopian tubes are most closely associated with decreased fecundity. Male factors A varicocele is a dilatation of the pampiniform plexus of veins that drain the contents of the scrotum. Varicoceles appear to reduce semen quality in some men and their correction improves semen quality. The ultimate effect of correction on fertility is less clear. Varicoceles may adversely affect semen quality by exposing the testis to temperatures higher than those in nonaffected men or by exposing the testis to abnormally high concentrations of gonadotoxic substances. Both effects appear to result from decreased venous ef ux from the affected testis. Blockage of the vas deferens or epididymis can result from con- genital abnormalities (i.e., mutations in the cystic brosis transmem- brane regulator gene; Chapter 26), from infection-associated scarring, or from inadvertent surgical ligation at the time of inguinal surgery. Purposeful, surgically induced blockage occurs with vasectomy; some vasectomized men regret their contraceptive decision and present to the fertility specialist requesting reversal. Damage to the bladder neck or injury to the lumbar sympathetic nerves involved in the ejaculation re ex may cause retrograde ejacula- tion, as may neurologic conditions such as multiple sclerosis if they inhibit normal innervation to the bladder neck. With retrograde ejacu- lation, sperm pass into the bladder upon ejaculation rather than exiting from the penile urethra. Therapy is unnecessary if fertility is not desired. If it is, medical therapies may augment bladder neck closure. If these fail, sperm may be harvested from alkalinized urine. Men may also produce very few or no sperm because of inadequate hormonal stimulation of the testis or because of gonadal failure. Men with hypogonadotropic hypogonadism may have pituitary gland or hypothalamic defects (e.g., Kallmann syndrome). They fail to secrete gonadotropins and so lack appropriate testicular function. These men are good candidates for treatment with exogenous gonadotropins. Most will respond and produce viable sperm. Men with gonadal failure (e.g. Klinefelter syndrome; 47XXY; Chapters 26 and 29), have few therapeutic options. Some with oligospermia or azospermia will never discover the cause of their disorder. Implantation abnormalities Implantation abnormalities encompass a group of endometrial and embryonic defects that interfere with the complex communication occurring between these entities early in the postconception period. Luteal phase de ciency (LPD) is the most discussed of the endometrial disorders that may directly impact implantation. LPD describes a group of endometrial maturation abnormalities that have been associ- ated with subfertility and recurrent pregnancy loss. In LPD of ovarian etiology, abnormal follicular development and ovulation lead to a rela- tive de ciency in progesterone production. This delays or minimizes the effects of progesterone in converting the endometrium into a secre- tory organ receptive to implantation. Diagnostic tests for the condition are presently suboptimal. Other factors Many other factors can in uence fecundity; several of these are immu- nologic. Antisperm antibodies have been identi ed in some patients with infertility but have also been detected in fertile couples. Their etiologic role and treatment remain unclear. In ammatory cells recruited into cervical mucus in response to cervical infections may affect sperm func- tion, perhaps through release of cytokines. Some women develop anti- bodies against negatively charged phospholipids commonly encountered in cell membranes. These antiphospholipid antibodies can inhibit placen- tal formation, activate the complement cascade and promote thromboses in small vessels leading to local ischemia and infarction. Although antiphospholipid antibodies more typically result in recurrent early mis- carriage, some women experience loss so early as not to know they are even pregnant. In these women, the antiphospholipid syndrome may initially manifest itself clinically as infertility. Genetic abnormalities such as the androgen insensitivity (Chapter 26) and gonadal dysgenesis syndromes (Chapters 26 and 27) can also cause infertility. Gonadotoxin exposure, including exposure to radia- tion, cigarette smoke and chemotherapeutic agents, can cause gonadal dysfunction and impaired fertility. Evaluation and treatment of infertility Evaluation initially involves assessment of the male partner with a semen analysis and documentation of ovulatory menstrual cycles and patent fal- lopian tubes in the female partner. In some couples, additional testing will be indicated. This may include: anatomic assessment of the uterine cavity, evaluation of ovarian reserve by measuring serum FSH and estradiol levels in the early follicular phase of the cycle, determining ovarian antral follicle counts or random anti-Müllerian hormone (AMH) testing. Lapar- oscopy and/or hysteroscopy may be indicated in some patients. Once the evaluation is complete, treatment is directed by the nd- ings. Anovulatory or oligo-ovulatory women are treated either by correction of any underlying problem such as hyperprolactinemia or hypothyroidism or by induction of ovulation. Medications used for the induction of ovulation work by a variety of mechanisms. The most commonly used is clomiphene citrate, an estrogen partial agonist/ antagonist that acts at the level of the hypothalamus and pituitary gland to block estrogenic negative feedback. This increases gonadotropin secretion. Aromatase inhibitors act to reduce circulating estrogen levels, again blocking negative feedback centrally and promoting gonadotropin production and release. Both medications require a func- tioning hypothalamic-pituitary-ovarian axis. Patients who are not candidates for, or who fail the prior therapies can be treated with gonadotropin (FSH +/− LH) injections. Reproductive tract surgery to remove endometriosis or a broid tumor may be recommended, although medical therapy for some of these problems is also available. In the past, tubal reconstructive surgery was a mainstay of infertility treatment; where readily availa- ble, assisted reproductive techniques like in vitro fertilization (IVF) have virtually eliminated the need for this approach. Treatments for male factor infertility may rst address the underly- ing etiology directly. This may include medical or surgical therapies, such as correction of a varicocele or correction of blockage in the vas deferens. More commonly, assisted reproductive techniques are used to bypass sperm problems. Sperm can be washed, concentrated and placed directly into the intrauterine cavity using arti cial insemina- tion. The sperm source can be the woman's partner or a donor. The widespread availability of the assisted reproductive technolo- gies has revolutionized infertility treatment, making pregnancies pos- sible under circumstances never before considered treatable. The most common treatment approach is IVF, in which multiple harvested oocytes are fertilized by spermatozoa in the laboratory. The resulting embryos are grown in the laboratory for 2-5 days, then a group of embryos is selected and transferred back into the cavity of the uterus. Standard IVF can be modi ed in a number of ways. Donor eggs or donor sperm can be used. In cases of severe male factor infertility, sperm can be injected directly into the oocyte cytoplasm to effect fertilization (intracytoplasmic sperm injection, ICSI). These sperm can be immotile. They can be retrieved directly from the vas deferens, epididymis, or even the testis in men with obstructive azospermia. Finally, recently developed technology allows genetic assessment of the embryos created through IVF. Using preimplantation genetic diagnosis (PGD), a single blastomere is removed from a developing blastocyst and screened for a variety of selected heritable single gene defects or for numerical chromosomal content. The results of screening can be used in selecting those embryos that will be transferred back to the uterus.

Labor

Labor is the process by which the fetus and its supporting placenta and membranes pass from the uterus to the outside world. It is de ned as regular uterine contractions that result in thinning and dilata- tion of the cervix so that the products of conception can pass out of the uterus. Labor involves three key processes: (i) a switch in myometrial activity, from a longer lasting, low-frequency irregular contraction pattern called "contractures" to the frequent, high-inten- sity, regular pattern known as "contractions"; (ii) softening and dilata- tion of the cervix; and (iii) rupture of the fetal membranes. Although labor may rst become apparent with the isolated appearance of any of these three elements, the physiologic events that produce them typi- cally occur simultaneously. Phases of labor It is useful to consider labor as a series of four physiologic phases, characterized by the release of the myometrium from the inhibitory effects of pregnancy and the activation of stimulants of myometrial contractility (Fig. 22.1). Phase 0 comprises the majority of pregnancy. During this phase, the uterus is maintained in a state of quiescence by one or more inhibitors of contractility. Candidate inhibitors include progesterone, prostacyclin, nitric oxide, parathyroid hormone-related peptide (PTHrP), calcitonin gene-related peptide, relaxin, adrenom- edullin and vasoactive intestinal peptide (VIP). Near the end of a normal pregnancy, the uterus undergoes the process of activation (Phase 1). During activation, a number of contraction-associated pro- teins increase under the in uence of estrogen. These proteins include myometrial receptors for prostaglandins and oxytocin, membranous ion channels and connexin-43, a key component of gap junctions. The increase in myometrial gap junctions during activation will electrically couple adjacent myometrial cells and maximize the coordination of contraction waves that move from the uterine fundus to the cervix. Phase 2 of labor is called stimulation. During stimulation, oxytocin and stimulatory prostaglandins (PGs) such as PGE2 and PGF2α can induce contractions in the previously primed uterus. The cervix dilates. The fetus, membranes and placenta are expelled from the uterus in a process called parturition. Phase 3 of labor follows parturition and is called involution. During involution, sustained contraction of the uterus promotes necessary hemostasis and eventually reduces the mas- sively enlarged postpartum uterus to a size only slightly larger than its prepregnant state. Initiation of labor The average human gestation lasts 280 days (40 weeks) from the beginning of the last menstrual period. Exactly what triggers human labor is unknown. Still, like other species that bear live young, the fetoplacental unit appears to control at what point in gestation labor will occur while maternal signals determine the time of day that it will start. The mechanisms used by the fetopla- cental unit to initiate labor vary from species to species. Humans mimic the mechanisms used by other primates much more closely than those used by more distantly related mammals. Sheep and rodents rely on progesterone withdrawal for labor initia- tion. In stark contrast, the initiation of labor in primates involves increases in placental estrogen synthesis (Fig. 22.2). Seemingly, this estrogen must be produced by the placenta, because systemic infusion of estrogen does not induce labor at term. Rather, infused androsten- edione will induce contractions and this effect can be blocked by inhibiting aromatase activity. Placental aromatase activity (Chapters 2 and 19) increases at term. This is accompanied by an increase in production of adrenal androgen precursors (e.g., androstenedione) by the fetus. Both support increased placental estrogen production. The stimulus for the increase in fetal adrenal androgen production near term is not known. It does not appear to arise from the fetal hypothalamus (corticotropin-releasing factor, CRH) or fetal pituitary adrenocorticotropic hormone (ACTH) because absence of appropriate brain formation in anencephalic fetuses does not prolong pregnancy. Rather, the stimulus is likely to be placental. Placental CRH is an excellent candidate. Placental CRH is biochemically identical to maternal and fetal hypothalamic CRH but differs in its regulation. Glucocorticoids exert negative feedback on the synthesis and release of hypothalamic CRH, but stimulate placental CRH. Placental CRH appears to stimulate fetal ACTH production and fetal adrenal steroid synthesis (e.g., androstenedione production). It may also have local effects within the uterus, fostering placental vasodilatation, prostag- landin production and myometrial contractility. In all species, an increase in prostaglandin synthesis by the decidua and the fetal membranes constitutes the nal common pathway in labor. Human uterine tissues are selectively enriched with arachidonic acid, an essential fatty acid that is the obligate precursor of those prostaglandins most important in labor: PGE and PGF2α. Both cyclo- oxygenase enzymes, COX-1 and COX-2, are expressed in the uterus. COX-2, the inducible form of the enzyme, appears to be sensitive to glucocorticoid induction. Evidence for the role of prostaglandins in labor includes observations that: (i) the concentrations of PGs in amniotic uid, maternal plasma and maternal urine are increased before the onset of labor; (ii) administration of PGs at any stage of pregnancy can initiate labor; (iii) PGs can induce cervical ripening and uterine contractions; (iv) PGs increase myometrial sensitivity to oxy- tocin; and (v) inhibitors of PG synthesis can suppress contractions and prolong pregnancy (e.g., the COX inhibitor, indomethacin). Like other smooth muscle cells, myometrial cells are triggered to contract by a rise in intracellular calcium (Ca2+). Prostaglandins raise intracellular Ca2+ by increasing Ca2+ in ux across the cell membranes, by stimulating calcium release from intracellular stores and by enhanc- ing myometrial gap junction formation. Oxytocin, a posterior pituitary hormone, has an important role in labor. Oxytocin acts through its membrane receptor on myometrial cells to activate members of the G protein subfamily. These, in turn, activate phospholipase C and inositol triphosphate, causing a release of intracel- lular Ca2+. Oxytocin seems to have a role in the maternal control of the time of day that labor will start. Several days to weeks before the onset of recognizable labor, myometrial activity switches away from contrac- tures to contractions. This switch invariably occurs when the lights go off in the animal's environment and ensures that delivery will occur when the mother is safely at rest away from predators. Nocturnally active animals will thus deliver during the day and vice versa. This circadian rhythm of uterine activity is accompanied by an increase in circulating oxytocin and in myometrial oxytocin receptors. Oxytocin also has an important role in promoting expulsion of the fetus from the uterus after the cervix is fully dilated. In fact, the oxy- tocin concentrations in the maternal circulation do not begin to rise until the expulsive stage of labor begins. Still, the gradual increase in the concentrations of oxytocin receptor in the myometrium during the second half of pregnancy may allow for lower concentrations of oxy- tocin to effect myometrial contractions prior to the onset of expulsion. Oxytocin can induce prostaglandin production and gap junction for- mation within the uterus, suggesting that it may act in synergy with other factors to initiate labor. To this point, oxytocin can be used clini- cally to induce and to stimulate labor. The fetus, placenta and fetal membranes all make oxytocin that is selectively secreted toward the maternal compartment.

Ch 27: Abnormalities of female sexual differentiation and development

Structural anomalies Structural anomalies of the uterus, cervix and vagina are the most common abnormalities of sexual differentiation seen in women. They arise from embryologic abnormalities of Müllerian system develop- ment (Chapters 5 and 6). The most severe form involves complete absence of the reproductive tract, including the vagina, uterus and fallopian tubes. Such agenesis of the Müllerian system is known as Mayer-Rokitansky-Kuster-Hauser syndrome, and is the second most common cause of primary amenorrhea (Chapter 30). The remainder of the anomalies result from failure of the Müllerian system to fuse in the midline or to remodel in the midline after fusion to form a single uterine cavity (Fig. 27.1). The most dramatic form of fusion anomalies occurs when the Müllerian ducts fail to fuse along their entire length, resulting in the formation of two vaginas, two cer- vices and two separate uterine horns (double uterus or uterus didelphys). More commonly, only the upper portion of the uterus fails to fuse. The uterine body may then remain separated as two horns (bicornuate uterus or uterus bicornus) or, in milder cases, a dimple may be noted in the contour of the uterine fundus (arcuate uterus). Occasionally, only one side of the Müllerian system will develop, resulting in a hemi-uterus and a single fallopian tube (unicornuate uterus or uterus unicornus). Failure to resorb the midline of the Müllerian ducts after fusion typically results in a uterine septum. A septum may be complete, running from the cervix to the fundus, or incomplete, involving only the uterine fundus (subseptate uterus). Occasionally, the vagina canal- izes improperly and a vaginal septum will occur. This can occur in isolation or in conjunction with a uterine anomaly. Vaginal septa can be either longitudinal or horizontal. The longitudinal septum is remi- niscent of those uterine anomalies resulting from failure of the Mülle- rian midline to resorb. Horizontal vaginal septa are thought to represent a failure of the vaginal plate to resorb at the site where it fuses with the Müllerian ducts. Many women with structural anomalies of the reproductive tract are asymptomatic and never diagnosed. Others with Müllerian tract abnor- malities may present with primary amenorrhea, recurrent miscarriages, preterm delivery and breech presentation at term. Because the mes- onephros is closely involved in directing the development of the internal genitalia, the nding of a uterine anomaly should prompt an evaluation of the urinary system for an accompanying anomaly. Exposure to diethylstilbestrol In utero exposure to diethylstilbestrol (DES) occurred in individuals born between 1940 and 1971 whose mothers were given the synthetic estrogen in the hope of preventing a miscarriage. DES was subse- quently shown to cause congenital abnormalities in women and, to a lesser degree, in men. The most frequently seen abnormalities in women are abnormally shaped cervices. These cervices have been described as coxcomb, hooded or hypoplastic. The uterine muscula- ture may also be abnormally formed in DES-exposed women such that the uterine cavity assumes a T-shape on hysterosalpingography or saline-infusion sonohysterography. DES appears to cause these abnor- malities via inappropriate activation of estrogen-dependent genes involved in differentiating the cervix and upper third of the vagina from the lower vagina. This results not only in the structurally abnor- mal cervices and uteri, but also in persistence of cervical glandular epithelium in the vagina (vaginal adenosis). In utero DES exposure is associated with an increased risk of reproductive failure, including infertility (likely from failed implantation), recurrent pregnancy loss and preterm delivery. DES daughters are also at increased risk for malignancies, speci cally clear cell adenocarcinoma, arising in sites of vaginal adenosis. This is thought to result from exposure of the ectopic cervical glandular-type epithelia in the vagina to neoplastic inducers not usually accessible to the upper reproductive tract. Occasionally, clinicians will observe cervical and uterine abnor- malities that look exactly like those caused by in utero DES exposure in women never exposed to DES. Congenital adrenal hyperplasia Ambiguous genitalia in a newborn infant are most commonly caused by congenital adrenal hyperplasia (CAH). This diagnosis accounts for 40-50% of all cases of ambiguous genitalia. Depending on the degree of the defect and the particular steroidogenic enzyme that is dysfunc- tional, neonatal effects can be variable. Affected female infants may have a common urogenital sinus containing the vagina and urethra, which opens at the base of an enlarged phallus resembling a penis. The labia majora may be hypertrophied or fused and thus resemble an empty scrotum. Some female infants will appear like a male with hypospadias and cryptorchidism. Others will only exhibit mild to moderate clitoromegaly. Some of these infants will have accompany-ing hypertension (5%) or life-threatening salt wasting (30%) and this will aid in making the diagnosis soon after birth. Those carrying the most common defect, moderate 21β-hydroxylase de ciency, will have no other identifying characteristics. The nding of a normal female karyotype in a newborn assigned to the male gender in the deliv- ery room requires an evaluation for CAH. The primary defect in all types of CAH is the absence of one of the enzymes necessary for steroidogenesis. The most common forms involve the enzymes that convert androgens to the adrenal steroids (Table 27.1). In the absence of one of these enzymes, no steroidal end-product will be produced by the adrenal gland to feed back on the hypothalamic-pituitary axis and regulate adrenocorticotropic hormone (ACTH) secretion. Excess ACTH will continue to stimulate the adrenals to produce more of the steroid products prior to the enzymatic block. These products are then shunted toward androgen-forming pathways. Adrenal hyperplasia with excess androgen production will result. This is of little consequence in the male fetus but will result in masculinization of the androgen-sensitive external genitalia in a female fetus. Because the female fetus has neither testes nor Mülle- rian-inhibiting substance (MIS), females affected by CAH will have uteri and vaginas. The degree of hypertrophy and fusion of the external genitalia in CAH females will depend on the quantity of androgen involved and on the developmental timing of androgen exposure. Masculinized infants with ovaries and a 46XX karyotype are called female pseudohermaphrodites. Therapy for female infants masculinized as a result of CAH includes glucocorticoid administration to suppress adrenal androgen secretion and genital reconstructive surgery. Infants who also have a defect in aldoster- one synthesis will also require mineralocorticoid replacement. Virilization of female infants by maternal or exogenous androgen exposure occurs only when those androgens are unable to be converted to estrogens by placental aromatase. Therefore, infants born to mothers with CAH are not at risk unless the child has inherited the genetic defect from both parents and also carries the enzymatic de ciency. Infants born to mothers with an androgen-producing tumor may be virilized if the particular androgen produced cannot be aromatized (e.g., dihy- drotestosterone, DHT) or it quantitatively exceeds the high aromatiza- tion capacity of the placenta. Maternal administration of synthetic progestins with androgenic activity has also been associated with viri- lization of the female neonate; use of synthetic progesterones is con- traindicated in pregnant women. Female virilization that has resulted from in utero steroid exposure but has no accompanying risk for post- natal exposure can be treated with reconstructive surgery alone. Turner syndrome Women with Turner syndrome are often identi ed when the physical characteristics of short stature, webbed neck, shield chest and increased carrying angle accompany primary amenorrhea. The fundamental defect in Turner syndrome patients is the absence of a second sex chromosome(i.e., a 45X karyotype). In the absence of a functional second sex chromosome, the germ cells in the gonad do not survive past the embryonic period and a normal ovary or testis does not develop. Gonadal steroid synthesis and secretion do not occur during embryogenesis or at puberty. Systems other than reproduction are affected by Turner syndrome. Women with the disorder have an increased incidence of renal anomalies, autoimmune diseases and cardiac anomalies, particularly coarctation of the aorta and aortic aneurysms. Turner syndrome is the most common of a group of dis- orders known as gonadal dysgenesis. Most individuals with gonadal dysgenesis have a female phenotype at birth. If the entirety of the second sex chromosome is missing, both the external and internal genitalia will be female. After puberty, these female structures will remain infantile because of the lack of ovarian estrogens from the nonfunctional gonad. If any remnant of a second sex chromosome is present in an individual with gonadal dysgenesis, the phenotype will depend on the speci c genes retained. For instance, if the SRY locus is present and translocated onto another chromosome, signals to begin testicular differentiation will occur. MIS will be pro- duced and the Müllerian duct system will regress. Despite MIS pro- duction, these individuals will have a rudimentary testis and lack androgen production. They will be born with female external genitalia, but lack a vagina and other female internal reproductive structures. Primordial Wolf an ducts may be identi ed at laparotomy along with ovotestes. These rare individuals are true hermaphrodites. Sex chromosome mosaicism (multiple cell lines of different sex chromosomal composition) is not uncommon in Turner syndrome. Individuals carrying any portion of the Y chromosome, including SRY alone, may have a testicular component to their dysgenetic gonad. These patients are at risk for gonadal malignancies and may have functional testicular tissue that causes virilization at puberty. Therefore it is important to con rm any suspected diagnosis of Turner syndrome using karyotype analysis. Some experts recommend using a DNA probe against SRY as well. Individuals who possess a cell line containing a Y chromosome or who carry SRY should undergo bilat- eral gonadectomy prior to puberty to eliminate the possibility of viri- lization or cancer. If sex chromosome mosaicism involves a second X chromosome, functional ovarian tissue may exist within the gonad. Women with such mosaicism may experience normal female puberty and even retain fertility for a brief period of time. Early menopause invariably occurs because the abnormal chromosomal constitution causes development of only a limited number of functional ovarian follicles. A woman with complete Turner syndrome or XX mosaicism can carry a pregnancy conceived through in vitro fertilization using donated oocytes. Her infantile uterus will require extensive hormonal priming.

Ch 12 Puberty in Girls

Puberty is the process by which the immature individual will acquire the physical and behavioral attributes that allow him or her to reproduce. In girls, puberty is largely the response of the body to the widespread actions of estrogens, secreted by the newly awakened plural-ovaries under the in uence of gonadotropins secreted by the anterior pituitary. While the progression of pubertal changes is predictable, age of onset differs dramatically in different areas of the world and even among chil- dren of different ethnic backgrounds within a particular region. Eco- nomic disparities may also be re ected in the age of pubertal onset. Physical changes of puberty In North American and European girls, puberty visibly begins with breast development between the ages of 8 and 10. Other secondary sexual characteristics appear over the ensuing 2.5 years. Puberty cul- minates with onset of menstruation. The average age of menarche in Caucasian girls is 12.8 ± 1.2 years and, on average, 4-8 months earlier in African-American girls. The physical changes of puberty in girls have been divided into ve stages using a system developed by Marshall and Tanner, who exam- ined groups of English girls as they went through sexual maturation (Fig. 12.1). They then classi ed the relative and absolute changes in the sexual characteristics of the participants. Although they did not regard their ndings as universal, their system has been widely used to describe the timing and progression of typical pubertal changes. Their descriptions must be recognized as speci c to the demographics of their study population and to the years covered by the study. Pat- terns persist, but the characteristics and timing of these changes are affected by race, nutrition and other genetic and environmental factors. Adrenarche This describes the contribution of the adrenal gland to puberty in both girls and boys. It is a developmentally programmed increase in adrenal synthe- sis and secretion of the weak androgens: androstenedione, dehydroepian- drosterone (DHEA) and dehydroepiandrosterone sulfate (DHEA-S). Adrenarche begins at about ages 6-8 years in girls. Secretion of weak adrenal androgens precedes the visible onset of puberty by about 2 years. DHEA and DHEA-S are responsible for initiating growth of pubic and axillary hair as well as growth of and secretion by axillary sebaceous glands. Axillary and pubic hair appear in parallel with the beginning of breast development and visibly mark the onset of puberty in girls. The exact trigger for adrenarche is not known. It is independent of adenocorticotropic hormone (ACTH) release, gonadotropin release and ovarian function, and appears to be an intrinsic, programmed event within the adrenal gland. Adrenarche is distinct from the other events of puberty (pubarche) and either may occur in the absence of its counterpart. Breast development (thelarche) The mammary gland, or breast, is an ectodermal derivative. The breast tissues are remarkably sensitive to hormones. Such hormonal effects are most notable during embryonic development and after puberty. The basic structure of the breast is common to all mammals although there exist wide variations in the number of mammary glands, their size, location and shape. Each mammary gland comprises lobulated masses of glandular tissue. Glandular tissues are embedded in adipose tissue and separated by brous connective tissues. Each of the lobes contains lobules of alveoli, blood vessels and lactiferous ducts. See Chapter 23 for a more detailed description of the structure and function of the human breast. At birth, the breasts consist almost entirely of lactiferous ducts with few, if any, alveoli. These rudimentary mammary glands are capable of a small degree of secretory function ("witch's milk") within a few days of birth. Breast secretion in the neonatal period occurs in response to the high prolactin levels in the newborn infant following prior exposure of the fetal breast to high concentrations of placental estro- gen during gestation. After placental estrogens are cleared from the neonatal circulation, the breast enters a dormant phase until puberty. With the onset of puberty, ovarian estrogens induce growth of the lactiferous duct system. The ducts branch as they grow and their ends form into small, solid, spheroidal cell masses. These structures will form the lobular alveoli. The breast and alveoli enlarge. With menarche, cyclic estrogen and progesterone secretion begin and an extra phase of ductal and rudimentary lobular growth will occur. Adrenal corticos- teroids further enhance duct development. The breasts continue to increase in size for some time after menarche due to deposition of fat and additional connective tissue. Final breast differentiation and growth will not occur until pregnancy. Secondary sexual characteristics Ovarian estrogens also produce the following changes in pubertal girls: • Pubic hair. • Keratinization (corni cation) of the vaginal mucosa. • Enlargement of labia minora and majora. • Uterine enlargement. • Increased fat deposition in hips and thighs. Somatic growth The pubertal growth spurt in girls typically begins 2 years before it begins in boys, accounting for about 50% of the 12cm difference in average height between men and women. The other 50% results from a slower rate of growth during the spurt in girls compared with boys. The mechanisms by which sex steroids induce bone growth in girls are the same as in boys (Chapter 11). Structural growth ceases at a median age of 17 years in girls. Menarche The term used to describe the onset of menstrual cycles. It is the culmination of a complex sequence of events that involves maturation of the hypothalamic-pituitary-ovarian (HPO) axis to produce both mature ova and an endometrium that can support a zygote if fertiliza- tion should occur. The three stages of maturation of the HPO axis include: (i) an increase in the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the pituitary gland; (ii) ovarian recognition of, and response to these gonadotropins, allowing production of ovarian steroids (estrogen and progesterone); (iii) estab- lishment of positive feedback regulation of the hypothalamus and pituitary gland by estrogens. The combination of these maturational events permits ovulation. Throughout childhood, FSH and LH concentrations within the pitui- tary gland and plasma of boys and girls are low. As described in Chapter 11, the pulse amplitude and frequency of FSH and LH release are also low, suggesting the gonadotropin-releasing hormone (GnRH) pulse generator is cycling slowly. This characteristic pattern has been called the juvenile pause. The rst endocrinologic manifestation of puberty is an increase in FSH and LH pulse amplitude. At its initiation, this increase is most notable during sleep, although the diurnal sleep- awake difference in FSH and LH secretion is almost obliterated by the end of puberty. The initiation of puberty remains incompletely understood. Still, most agree it must be related to a release of the hypothalamic GnRH pulse generator from CNS inhibition. There has been much interest in the observation that the age of menarche decreased by 2-3 months per decade during the 150 years preceding World War II and then stabilized over the next 50 years. A decrease was again noted in recent studies, thought to represent the in uence of optimal nutrition. Onset of menarche is closely related to attainment of a crucial percentage of body fat. Two metabolic signals have been recently identi ed that can act centrally and may be causal in pubertal events: insulin-like growth factor 1 (IGF-1) and leptin. Serum IGF-1 levels increase during childhood and peak at puberty: the increase parallels that of DHEA-S, the marker of adrenarche. Leptin, a hormone signaling satiety, inhibits neuropeptide Y (NPY). NPY is a mediator of food intake, but also controls GnRH neuronal activity in the hypothalamus. Serum leptin levels increase in both sexes prior to onset of puberty. Rising leptin levels inhibit NPY. This, in turn, releases GnRH from its prepubertal inhibition. Leptin levels continue to rise throughout puberty among healthy females, but fall fairly rapidly after pubertal initiation in males. Maturation of the ovary at puberty allows initiation of estrogen pro- duction by the granulosa cells surrounding the ova. Waves of granulosa cells undergo development and subsequent atresia as puberty progresses. Ova begin to mature under the in uence of ovarian estrogen produced by these granulosa cells. In addition to oocyte maturation, estrogen from the granulosa cells will regulate production of gonadotropins by the pituitary gland. With complete maturation of the HPO axis, this estro- gen will drive maturation of a dominant ovarian follicle, culminating in ovulation. With ovulation of the rst ovum, the collapsing ovarian follicle recon gures itself as a corpus luteum and begins to produce progesterone. The endometrium responds to estrogen by proliferating and to progesterone by converting to a secretory tissue capable of sup- porting embryo implantation. In the rst years after menarche many menstrual cycles will be anovulatory, re ecting the incomplete matura- tion of the hypothalamic positive feedback response to ovarian estro- gen. The menstrual bleeding patterns often encountered soon after menarche represent continuous exposure of the endometrium to estro- gen and sloughing of proliferative or hyperplastic endometrium. Because no corpus luteum forms in the absence of ovulation, the endometrium cannot exhibit the progesterone effect that makes men- struation a self-limited phenomenon. This anovulatory bleeding can be very unpredictable and quite heavy. By 5 years after onset of menarche, 90% of girls have regular, ovulatory menstrual cycles.

Infertility

Introduction: Infertility is defined as the inability to conceive after 1 year of regular unprotected intercourse. Approximately 80% of couples achieve pregnancy after 1 year of attempting; thus, 20% of couples are infertile. Infertility is age-related in women. The infertility rate is 10% in women <30 years of age, 15% in those 30 to 35 years of age, 25% to 30% at 35 to 40 years of age, and 30% to 40% in those >40 years of age. Female causes of infertility comprise 50% of all infertility: 40% of female infertility is due to tubal disease (often due to chlamydial infection), 40% anovulatory, 20% due to cervical immunology or environmental factors. Male causes account for one third of infertility cases. Etiology is usually unclear. In 10-15% of couples, abnormalities are found in both the woman and man. No true abnormality is found in 10 to 15% of couples. This is defined as unexplained infertility. Evaluation: Complete work-up should be started after 1 year of regular unprotected intercourse. Criteria for earlier evaluation: women >35 years of age; women having menses less frequently than every 35 to 40 days; known or suspected uterine or tubal disease or endometriosis; men known to be subfertile. Evaluating female factors: History: A thorough history often uncovers cause(s) of infertility. Considerations: age; duration of infertility; menstrual pattern; past pregnancies; tubal infections; thyroid disease; prior treatment; current use of medications. Lifestyle factors: quality of sperm and oocytes affected by cigarette smoking; excessive exercise can affect ovulation and fertility. Examination: Pelvic examination to rule out an ovarian cyst, enlarged uterus, scarring from endometriosis. General physical to assess for endocrine problems, e.g., enlarged thyroid, hirsutism, acanthosis nigricans, or obesity. Diagnostic tools: Establish ovulation and ovarian reserve: Women with regular menstrual cycles and moliminal symptoms are likely ovulatory. In all women, we measure FSH and Estradiol (E2) levels (on second or third day of menses) as a measurement of ovarian reserve. Ideally FSH levels should be <10 mIU/mL and Estradiol levels should be <70pg/mL. Day 3 FSH - <10 mIU/mL indicative of good ovarian function; 10 to 14 mIU/mL suggests subtle decrease in fertility; 15 to 19 mIU/mL suggests significant decrease in fertility; chance of patient conceiving "extremely low" if >16mIU/mL Referral to reproductive endocrinologist warranted if FSH>10 mIU/mL or Estradiol>70 pg/mL; E2 level should be tested with FSH - should be <70 pg/mL on second or third day of menses; elevated E2 within first few days of menses is a poor prognostic factor. Both are indirect tests of inhibin production by healthy follicles. TSH and prolactin should be measured in all women. Luteal phase progesterone: may be useful in determining ovulatory status; obtain one week before expected menses. Hysterosalpingography: a dye test performed in Radiology to evaluate the uterus and fallopian tubes -recommended for all patients. One possible exception could be anovulatory patients with no risk factors for tubal disease. One should establish ovulation with ovulation-inducing medication for "a few months;" if patient does not conceive, perform hysterosalpingography. Semen analysis is an essential test. A sperm count of >20 million/mL is consistent with normal fertility (couple has good chance of achieving pregnancy on their own or with intrauterine insemination [IUI].) Other (WHO) parameters of a normal semen analysis: 50% of sperm should be motile; >30% of sperm should be morphologically normal. If semen analysis is normal, no further work-up of the man is necessary. Repeat if abnormal as there is some day-to-day variation in semen parameters. If sperm count is 10 to 20 million/mL, natural pregnancy is unlikely (refer couple to reproductive endocrinologist for in vitro fertilization [IVF]); If sperm count is <10 million/mL, couple will need IVF and male should be referred to a urologist for evaluation. Most men with abnormal semen parameters have no history of problems with erection or ejaculation. Medical history for male factor infertility should include ruling out problems with erection or ejaculation. Other important history includes surgery involving testes, hernia repair, mumps orchitis, or testicular trauma. Laparoscopy is performed only in certain situations. Indicated when a woman has an ovarian cyst, a history of endometriosis, or previous gynecological surgery. Less useful tests: (a) Basal body temperature (BBT) is not very accurate; (b) postcoital test has very poor predictive value; (c) endometrial biopsy is painful and rarely provides helpful information. Work-up of amenorrheic patient: No evidence of hirsutism: measure FSH, prolactin, and TSH in patients with chronic anovulation. If values are normal and patient has positive response to progesterone withdrawal test, clomiphene is often effective. Evidence of hirsutism: same testing, but include testosterone, DHEAS, and 17-hydroxyprogesterone (17-OHP); perform glucose tolerance test or fasting glucose (approximately one third of women with PCOS have some degree of insulin resistance.) Irregular menses/anovulation: Rule out and treat underlying conditions, e.g., thyroid disease, hyperprolactinemia. With low-level hyperprolactinemia (20-30 ng/mL) cranial imaging is not usually required. Prescribe bromocriptine (dopamine agonist), bid to tid; may be associated with side effects, e.g., nausea, dizziness; cabergoline, 0.5 mg 1 to 2 tablets weekly, is better tolerated than bromocriptine. Progression of treatment - Irregular menses/anovulation: Clomiphene citrate- antiestrogen (tricks brain into ovulating) can be used in anovulatory women with normal TSH and prolactin levels who respond to a progestin challenge. Begin therapy with 50 - 100 mg for 5 days (dosage should take into consideration woman's weight); at proper dosage, up to 94% of women ovulate and 50% conceive. Possible negative effects on cervical mucus and endometrial lining. Limit therapy to 3 to 6 months. Associated with headaches, vasomotor flushes, abdominal discomfort (if severe, consider ultrasonography), blurred vision (discontinue), ovarian hyperstimulation (extremely rare) . With initial clomiphene citrate usage, day-24 measurement of progesterone is recommended: progesterone >3 ng/mL indicates ovulation, and clomiphene dose does not need to be increased. If conception is not achieved with dose of 200 mg, consider referral to reproductive endocrinologist (most likely woman requires injectable gonadotropins). Metformin elicits ovulation in non-obese, insulin-resistant women. Metformin (500 - 1000 mg bid) recommended with acanthosis nigricans, strong family history of diabetes, and other stigmata of PCOS. Gastrointestinal side effects associated with higher dosage. Clomiphene plus metformin: if woman does not ovulate after 2 to 3 cycles of combined therapy, refer to reproductive endocrinologist for therapy with injectable gonadotropins. Injectable gonadotropins (rFSH) require close monitoring and are generally reserved for use by a Board Certified Reproductive Endocrinologist. Infertility Treatment: Mild to moderate disease: unexplained infertility, mild tubal disease, endometriosis, mild pelvic adhesions, cervical factor. Treatment: clomiphene citrate with intrauterine insemination of concentrated washed sperm for 2 to 4 cycles; increases chance of pregnancy from 3-4% to ≈ 8-15%; if pregnancy does not occur, treatment progresses to injectable gonadotropins for 2 to 3 months; then In Vitro Fertilization (IVF). Laparoscopy is sometimes performed prior to administration of injectable gonadotropins, especially with significant history of STDs, pelvic infection, dysmenorrhea, dyspareunia or previous gynecologic surgery. Severe disease: caused by blocked fallopian tubes, severe male factor (sperm count <10 million/mL), failed rFSH/IUI. Treatment: IVF required. Donor oocytes are an option in ovarian failure; host uterus (gestational carrier) is also an option with severe uterine anomalies and Asherman's syndrome.

. Ch 8: Microscopic anatomy of the male reproductive tract

Testes The testes have two distinct functions: spermatogenesis and androgen production. Spermatogenesis occurs within distinct structures called seminiferous tubules (Fig. 8.1). These tubules lie coiled within lobules whose ducts all exit the testis into the epididymis. Androgen production occurs within pockets of specialized cells that lie in the interstitium between the tubules. The seminiferous tubules are surrounded by a basement membrane. Juxtaposed to the medial side of this basement membrane are the progenitor cells for sperm production. The epithelium containing the developing spermatozoa that line the tubules is known as the seminif- erous epithelium or germinal epithelium. In a cross-section of the testis, spermatocytes within a given tubule are in varying stages of maturation. Mixed among the spermatocytes are Sertoli cells. These are the only nongerminal cells in the seminiferous epithelium. Sertoli cells were aptly called "nurse cells" when rst described by Sertoli in 1865. They are responsible for the metabolic and structural support of the developing spermatozoa. All Sertoli cells make contact with the basement membrane at one pole and surround the developing sperma- tozoa at the other. Sertoli cells have large, complex cytoplasmic " ngers" that extend around many spermatozoa at one time. A wide variety of substances that are normally present in the circula- tion are excluded from the uid within the seminiferous tubule. This phenomenon is similar to that seen in the brain as the result of the blood-brain barrier. The male reproductive system displays its own blood-testis barrier. This barrier allows the testis to be one of very few immune-privileged sites in the human body. While the function of this barrier is incompletely described, its ultrastructural basis is known to be the tight junctions that form between adjacent Sertoli cells. The barriers created by these tight junctions divide the germinal epithelium into basal and luminal compartments. The basement com- partment contains the spermatogonia and the adluminal compartment, the maturing germinal cells. Spermatogenesis can be divided into three phases: (i) mitotic pro- liferation to produce large numbers of cells; (ii) meiotic division to produce genetic diversity; and (iii) maturation. The latter involves extensive cellular morphologic remodeling aimed at facilitating sperm transit to, and penetration of, the oocyte in the female tract. Primitive spermatogonial stem cells remain dormant in the testis until puberty. At puberty, they are activated and maintained in rounds of mitoses at the basement membrane of the seminiferous tubule. From this reser- voir of self-regenerating stem cells emerges several subtypes of sper- matogonial clones until, after the nal division, they exit mitosis as primary spermatocytes. Primary spermatocytes then undergo two meiotic cell divisions. These important divisions halve the number of chromosomes in the daughter cells. Cells undergoing the rst of these meiotic divisions have very characteristic differences in their nuclear morphology that has led to a speci c nomenclature (resting, leptotene,zygotene, pachytene and diplotene; Chapter 4). The rst meiotic divi- sion produces secondary spermatocytes (II) and the second, early haploid spermatids. The spermatids then undergo remarkable cytoplas- mic remodeling, during which a tail, mitochondrial midpiece and acrosome all develop. Almost all of the spermatid cytoplasm is expelled as residual bodies during this remodeling; only a small droplet of cytoplasm remains within the head of the mature sperma- tozoon. The surrounding Sertoli cells phagocytose the residual bodies, a process that may transmit information about the developing sperm cell to the Sertoli cell. Development of the spermatozoa within the seminiferous epithe- lium is a complex and highly ordered sequence of events in most mammalian species. In humans, the process appears somewhat less orderly, but still follows the general principles found in other species. In each, the number of mitotic divisions the spermatogonia undergo is xed. In humans, four mitotic divisions occur. The length of time for an early spermatogonium to develop into a spermatozoon ready to enter the epididymis is also xed and species-speci c. In humans, it takes 64 ± 4 days for this process. As the spermatocytes move through the maturation process, they also move in waves toward the lumen of the seminiferous tubule. The Sertoli cells enveloping the developing spermatozoa are homologs of the granulosa cells in the ovary. Sertoli cells phagocytose the extruded spermatid cytoplasm. They also function in aromatization of androgen precursors to estrogen, a product that exerts local feed- back regulation on the androgen-producing (Leydig) cells. Sertoli cells also produce androgen-binding proteins. Leydig cells perform the other major function of the testes - andro- gen production. The Leydig cells are homologous with the theca cells of the ovary. They produce large amounts of androgen from either circulating cholesterol or cholesterol made internally within their own smooth endoplasmic reticulum. Leydig cells are very large and, con- sistent with their intracellular activities, appear foamy by standard histologic assessment. The most easily damaged cells in the testis are the spermatogonia. Irradiation, excessive alcohol intake, dietary de ciencies and local in ammation can rapidly induce degenerative changes in these cells. Excess heat also induces extensive spermatogonial cell degeneration but does not affect the length of the spermatogenic cycle. Epididymis and vas (ductus) deferens The ducts forming the epididymis and vas deferens have muscular coats composed of an inner layer of circularly directed bers and an outer layer of longitudinally directed bers. The muscle component of these structures is responsible for peristalsis that moves the spermatozoa along the ducts. The ducts are lined with a mixture of secretory and cili- ated cells. The former aid in the generation of intratubal uids; the latter assist in directed transit of intratubal uids and cellular components. Seminal vesicles The alveoli of the seminal vesicles are lined with a pseudostrati ed epithelium whose cells contain numerous granules and clumps of yellow pigment. Some of the epithelial cells have agella. The secre- tion of the seminal vesicles is a yellowish, viscous liquid containing globulin and fructose. This secretion provides the majority of the ejaculate volume. Prostate gland The tubuloalveolar glands of the prostate are lined with an epithelium that is highly responsive to androgens. The acini of the central glan- dular zone that surrounds the ejaculatory ducts are large and irregular. By contrast, the acini of the peripheral glandular zone are small and regular. These striking differences in glandular architecture, along with the observation that several unique enzymes present in the seminal vesicles are present in the central but not the peripheral glan- dular zone, suggests different embryologic tissue origins for these two parts of the prostate (Chapter 6). The epithelium of the prostatic tubu- loalveolar glands produces the acid phosphatase and citric acid nor- mally found in semen. Penis The erectile tissue of the penis is a vast, sponge-like system of irregu- lar vascular spaces fed by the afferent arterioles and drained by the efferent venules. A pair of cylindrical bodies, the corpora cavernosa, is surrounded by a thick brous membrane called the tunica albuginea and separated by an incomplete brous septum. The veins draining the cavernous bodies lie just beneath the tunica. The interior of the cavern- ous bodies contains many partitions called trabeculae. Trabeculae are comprised of elastic bers and smooth muscle embedded within thick bundles of collagen and covered by endothelial cells.

TERATOGENIC EFFECTS OF DRUGS

Drugs that gain access to the fetus may produce pharmacologic effects like that in the mother, depending on the stage of fetal development. In addition, drugs and other chemicals can alter fetal development. A teratogen is an agent that causes an anatomic abnormality in the fetus. These abnormalities are referred to as malformations, when altered development occurs, and deformations, when abnormal forces change a normal structure as occurs with oligohydramniosis. Behavioral teratogens cause a defect in cognitive or psychosocial measures without producing detectable structural abnormalities. Teratogens include not only drugs, but also chemicals from occupational and environmental exposures and ionizing radiation. Major congenital defects are estimated to occur in about 1-3% of births with drugs as the cause in about 2-3% of these cases. Other causes are genetics, maternal diseases, and infectious agents. II. Background to Regulatory Considerations In the early 1960s thalidomide (used to prevent nausea and vomiting in the first trimester of pregnancy) was identified as the cause of numerous congenital defects, including failure of long-bone growth (phocomelia). This discovery prompted Congress to institute increased FDA requirements for testing drugs in animal models for their reproductive toxicity, including teratogenicity. In the 1970s a retrospective case-control study identified diethylstilbestrol (used to prevent miscarriage) as the cause of vaginal adenomas that occurred during puberty in female offspring. This delayed effect raised additional concerns about the teratogenic risk of drug use during pregnancy. Lawsuits in 1970s regarding the efficacious morning-sickness preparation Bendectin®, a combination of doxylamine (an antihistamine) and pyridoxine (Vitamin B6), led to its withdrawal from the U.S. market in the 1980s, despite scientific evidence of no increased risk of teratogenic effect, and reinforced policy of excluding women from clinical trials. (Note: In 2013 the FDA approved this drug combination as Diclegis®, and so it became available again for treatment of morning sickness.) The AIDs epidemic in the 1990s led to demand for inclusion of women in clinical trials of new antiviral agents and to a shift in NIH, FDA, and pharmaceutical industry practice to inclusion of women in clinical trials of all drugs that might be prescribed for women. In the late 1970s the FDA implemented a classification of drugs (A-D,X) to reflect the degree of teratogenic risk, based on evidence from animal and human studies (see below). Criticism by experts in the field (e.g., The Teratology Society) resulted in new FDA policy, effective June 2015, which requires manufacturers to provide detailed information in the label about studies on reproductive toxicology and teratogenicity for a newly approved drug, rather than just a classification assignment, and contact information for registries on drug-use outcomes in pregnant women. Summary of FDA classification criteria (replaced for new drugs as of 2015, still used for older drugs): A - No demonstrated risk to fetus based on adequate studies in pregnant women B - No demonstrated risk to fetus based on studies in animals but no adequate studies in pregnant women OR adverse effect in animals but no demonstrated risk based on studies in pregnant women C - Adverse effect demonstrated in animals but no adequate studies in pregnant women OR no animal studies and no adequate human studies D - Evidence of fetal risk in humans but potential benefits acceptable relative to potential risk X - Evidence of fetal risk based on animal or human studies and risk clearly outweighs potential benefit; absolutely contraindicated for use during pregnancy In addition to labeling, the FDA has implemented strategies for risk reduction, referred to as REMS (risk evaluation and mitigation strategy), for some teratogenic drugs. The goal of a REMS is to increase assurance that patients and providers are aware of a drug's teratogenic risk and to implement approaches to increase safe use, such as limiting distribution, confirming use of pregnancy tests prior to use, and stipulating types of contraception during use. For example, a REMS is required for access to thalidomide, which is currently approved for use in multiple myeloma and leprosy. III. Identification of Teratogenic Risk A. Animal studies: FDA regulations for new chemical entities require that studies be conducted and data submitted on reproductive toxicity as part of the NDA. These data include drug testing in two species (rat or mouse and rabbit) with examination for effects on fertility, congenital defects, fetal survival, and birth weight. Species differences in teratogenic risk are one challenge to predicting human risk based on animal data. B. Human exposures: Case reports and retrospective studies may provide the evidence to link a chemical to teratogenic outcomes in human offspring. C. Mechanistic studies: Certain types of drug effects provide a biological hypothesis for predicting increased likelihood of teratogenic outcomes. Examples include evidence of mutagenic effects, transcriptional effects (especially on genes involved in tissue differentiation), and effects to deplete folic acid (deficiency increases risk of spina bifida). IV. Factors that affect Teratogenic Risk A. Exposure Time during Gestation The risk and specific type of teratogenic effect are highly dependent on the exposure time during gestation. For drugs that produce abnormalities in tissue differentiation and organ formation the teratogenic risk is greatest for exposures during the period of organ formation. These gestational periods, listed below, are primarily within the first trimester of pregnancy (3-9 weeks). During the second and third trimester, following the formation of the major organs, more minor morphologic effects may occur. Since during this period the fetus is undergoing growth, abnormalities can also result from inhibition of growth overall (sometimes due to placental effects) or growth of specific organs. Gestational Period Site of Major Abnormality 3-5 wk CNS 3.5-6 wk Heart 4.5-7 wk Eyes, limbs 4-8 wk Ear 7-8 wk Teeth, palate 7-9 wk External genitalia B. Dose Dependence The risk of a teratogenic effect is also dependent on the concentration of a drug achieved in fetal tissue. Fetal concentration is dependent on the magnitude of the maternal plasma concentration and transport from the maternal circulation across the placenta. Access through the placenta (generally by passive diffusion) is enhanced by low molecular weight (<1000 Da) and high lipophilicity. The maternal plasma concentrations are dependent on the chemical's pharmacokinetic parameters and the dose. For a number of teratogens data document the correlation between dose and incidence of teratogenic outcome. An example is the known relationship between the amount of alcohol intake per day during pregnancy and the incidence of fetal alcohol syndrome (facial and CNS abnormalities) and decreased birth weight. The bioavailability by a given exposure route influences the maternal plasma concentrations and therefore the teratogenic risk. For example, oral formulations of Vitamin A analogues confer a much greater risk than topical formulations, which typically have much lower bioavailability. V. Some Major Teratogenic Drugs and their Adverse Effects Drug Adverse Effects Comment ACE inhibitors & ARBs Renal growth retardation and renal failure Primary effect is in second and third trimester. Antiepileptics valproic acid Spina bifida Fetal risk from seizures may necessitate use of antiepileptics; if valproate must be used, then folate is supplemented. Cancer chemo-therapeutics and immunosuppressants Abortion; CNS, palate, and other abnormalities Teratogens include the cell replication inhibitors; mabs are unlikely to cross placenta Ethanol Microcephaly, mental retardation, typical facial dysmorphogenesis, small palpebral fissures Referred to as fetal alcohol syndrome Statins Altered bone formation Risk to fetus does not justify benefit to the mother. Tetracyclines Tooth discoloration, enamel hypoplasia, altered bone growth Thalidomide Phocomelia (defective development of arms or legs) and other defects depending on exposure time Risk is highest among all known teratogens, estimated at 25% of exposures. Vitamin A analogues Craniofacial, cardiac, thymic, and other abnormalities Risk is much higher with oral as compared to topical formulations. Warfarin CNS and skeletal defects Heparin is substituted if anticoagulation is required during pregnancy.

Ch 46 Sexually transmitted diseases of bacterial origin

Gonorrhea Gonorrhea is the most frequently reported communicable disease in many of the more developed countries. Rates are 5-50 times higher than in the less developed world. The Gram-negative coccus that causes the disease is called Neisseria gonorrhoeae. It is a highly specialized organism that requires a mucosal surface to gain access to the body. The most important health consequence of gonorrheal infections is fallopian tube damage and the associated predisposi- tion to ectopic (tubal) pregnancies and infertility. In men, urethritis is the most common clinical manifestation of gonorrhea. Symptoms include dysuria and/or a purulent urethral dis- charge. Complications of gonorrhea are uncommon in men, but ure- thral stricture, epididymitis and prostatitis can occur. Between 20 and 30% of heterosexual men with symptomatic gonococcal urethritis are simultaneously infected with Chlamydia trachomatis. Gonococcal infection in women is often asymptomatic. Morbidity associated with the infection, however, is far greater than that seen among infected men. A signi cant number of women diagnosed with gonorrhea are identi ed in sexually transmitted disease (STD) clinics as the asymptomatic consort of an infected partner. Uncomplicated urogenital gonococcal infection in women may present as dysuria from urethritis, vaginal discharge from cervicitis, or purulent drainage from the Skene or Bartholin glands at the vaginal introitus. Pelvic in ammatory disease (PID) is a term used to describe infection of the upper genital tract, including endometritis, salpingitis and perito- nitis. Neisseria gonorrhoeae and C. trachomatis are the two pathogens most commonly isolated from women with positive cultures for PID. Women with gonococcal PID present with lower abdominal pain, abnormal uterine bleeding, dyspareunia (pain with intercourse) and fever. Although mortality from PID is low, morbidity is extremely high. PID is an important risk factor for chronic pelvic pain, infertility and tubal pregnancies. In some areas of Africa, up to 50% of women are infertile as a result of tubal occlusion from gonococcal PID. Other serious clinical manifestations include disseminated gonococ- cal infection (DGI) and gonococcal ophthalmia neonatorum, a severe form of conjunctivitis affecting newborn infants who acquire the infection in the birth canal. Neonatal gonococcal ophthalmia can result in blindness if left untreated. It is a rarity in developed countries because neonatal ocular prophylaxis is mandated at birth, but remains a signi cant problem in many resource-poor parts of the world. Gonorrhea is treated with antibiotics. Due to antibiotic resistence pro les, a parenteral cephalosporin plus doxycycline or azithromycin is currently rst-line therapy for uncomplicated infections, but the choice of antibiotic evolves with resistence pro les and the propensity for the organism to be associated with other STDs. Epidemiology of gonorrhea Gonorrhea is largely a disease of youth. Incidence peaks in men and women at ages 18-24 years. In addition to age, the risk factors include low socioeconomic status, urban residence, unmarried status, non- white race, male homosexuality and prostitution. Biology of N. gonorrhoeae Gonococci enter the body by attaching to nonciliated columnar mucosal epithelial cells using specialized surface structures on the bacteria known as pili (Fig. 46.1). Following attachment by the pili, the gono- cocci are endocytosed by the cell. At this stage, a lipopolysaccharide (LPS; endotoxin)-mediated event is activated and nearby cells are killed. Following endocytosis of the bacteria, vacuoles containing viable and replicating gonococci pass through the cell from the mucosal surface to the subepithelial membrane. They are then released into the underly- ing tissues. The surface damage caused by the gonococcus allows other pathogens, such as chlamydia, to gain access to the upper reproductive tract and cause multiorganism PID. Movement of the gonococci to subepithelial sites also explains frequent failure to document its pres- ence in the fallopian tube despite cervical culture-positive PID. Gonococci develop their antibiotic resistance through plasmid- mediated and chromosomal mechanisms. Most plasmid-mediated resistance is to penicillin and tetracycline. Chromosomally mediated resistance is more general and involves mutations that alter cell wall permeability or the af nity of binding proteins to antibiotics. Chlamydia There are many similarities between the infections caused by N. gon- orrhoeae and Chlamydia trachomatis (CT). Chlamydiae access the body by invading the same epithelial cells of the endocervix, urethra, endometrium, fallopian tubes, rectum and conjunctivae that are host to the gonococcus. Infections in men are relatively asymptomatic and of low morbidity; the major consequence of infection in the male is the risk of transmission to a female partner. In women, gonococcal and chlamydial infections can result in PID, chronic abdominal and pelvic pain, infertility and ectopic pregnancy. There is risk to the newborn infant from a birth canal infected with gonococci or chlamy- diae. The greatest clinical difference between female infection with gonococci and CT is that chlamydial PID is often asymptomatic. Hence, chlamydial infection is a major public health hazard because of the potential for undetected serious damage to the upper reproductive tracts of women. Chlamydia trachomatis is the most common STD in the USA and Europe. Chlamydiae are unique bacteria. Like viruses, they are obli- gate intracellular parasites and can only be propagated in cell culture. Chlamydia causes about 50% of the cases of nongonococcal urethritis in men. In women, chlamydia can cause mucopurulent cervicitis and the "urethral syndrome." In the latter, pain on urination is associated with the presence of white blood cells, but no bacteria, in the urine. Unlike gonorrhea, chlamydial infection of the upper genital tract often invades the endometrium and even the fallopian tubes without causing overt signs of PID. Such subclinical infection may rst be recognized with diagnosis of the consequent infertility or ectopic pregnancy. Several strains of chlamydia cause a unique disorder known as lymphogranuloma venereum (LGV), a chronic disease that, like syphilis, has three clinical stages. The primary lesion of LGV is a small, inconspicuous papule of the genitalia that quickly and quietly disappears. The secondary stage of LGV is characterized by fever, malaise and either acute lymphadenitis of the inguinal region (bubo formation = inguinal syndrome) and/or acute hemorrhagic proctitis (anogenitorectal syndrome). Most people recover uneventfully from the second stage. In an unfortunate few, the chlamydiae persist in the anogenital tissues and incite a chronic in ammatory response that can cause genital tract ulcers, stulae and strictures. LGV is endemic in much of the less developed world but sporadic in the USA and Europe. Neonates exposed to chlamydia in the birth canal may develop afebrile pneumonia or conjunctivitis that can progress to blindness. Unlike gonococci, chlamydiae require prolonged treatment to eradi- cate the intracellular reservoir of the bacteria. First-line therapy is presently azithromycin or doxycycline. In vitro data and clinical experience indicate that CT may persist within certain infected cells for many years. Because of frequent coexistence of gonorrhea and chlamydial infection, most treatment regimens include antibiotics active against gonococci and chlamydia. True antibiotic resistance is rare in chlamydial infections. Epidemiology of chlamydial infection Chlamydia infection is a disease of the young. Additional risk factors include low socioeconomic status, a high number of sexual partners and oral contraceptive use. Barrier methods of contraception (condom, diaphragm, diaphragm plus spermicide) reduce risk. Biology of chlamydia The chlamydiae are structurally complex microorganisms. Like viruses, chlamydiae are obligate intracellular parasites. They are clas- si ed as bacteria because they contain both DNA and RNA. Like Gram-negative bacteria, they possess outer membrane proteins and an LPS. Chlamydiae differ from all other bacteria in that their growth cycle is characterized by transformation between two distinct forms: the elementary body and the reticulate body (Fig. 46.2). The elemen- tary body is a highly infectious, rigid extracellular growth form that is metabolically inactive. The elementary body attaches to nonciliated columnar or cuboidal epithelial cells and induces ingestion by the host cell. The elementary body-containing phagosome does not fuse with host cell lysosomes, a characteristic crucial to CT survival and unique to only a few organisms (Mycobacterium tuberculosis is another). Within the phagosome, the elementary body reorganizes into a larger, metabolically active, fragile and noninfectious reticulate body. The reticulate bodies divide repeatedly by binary ssion within the phago- some of the host cell. They will ultimately reorganize back into infec- tious elementary bodies that are released when the host cell dies. There are 15 different serotypes or serovars of chlamydiae. These serovars are identi ed as A-K, Ba, and L1, L2 and L3. Strains D-K are associated with chlamydial STDs. L1, L2 and L3 cause LGV.

Ch 6: Phenotypic sex differentiation

Internal genitalia Unlike the bipotential gonads and external genitalia, the male and female internal genitalia arise from separate duct systems (Fig. 6.1). Development of these structures occurs in parallel and in close physi- cal proximity with the developing urinary system. Both begin to occur at about 4 embryonic (6 menstrual) weeks. The primordial kidney (mesonephros) is composed of tubules and a duct known as the mes- onephric or Wolf an duct. The Wolf an duct grows out from the tubules toward the urogenital sinus. The mesonephric tubules make contact with the primitive sex cords just as the gonad begins to dif- ferentiate. Simultaneously, an inpocketing of the coelomic epithelium near the lateral edge of the mesonephric ridge forms the paramesone- phric or Müllerian duct. As kidney development proceeds (metane- phric stage), the mesonephric structures will become totally incorporated into the reproductive tract and lose their urinary function. The Wolf an and Müllerian ducts are primordia for the internal organs of reproduction in the male and female, respectively. In each sex, the other duct system typically disappears by the 3rd fetal month, leaving behind vestiges that are usually unimportant clinically. In the normal male embryo, the secretion of a peptide called Müllerian-inhibiting substance (MIS; also known as anti-Mullerian hormone or AMH) occurs under the direction of sex-determining region of the Y chromosome (SRY). MIS is secreted by cells that will become Sertoli cells in the adult testis. MIS causes the Müllerian duct to degenerate. Testosterone is produced by those testicular cells des- tined to become Leydig cells in the adult. Testosterone directs develop- ment of the Wolf an duct system to form the epididymis, vas deferens and seminal vesicles. In contrast to the adult, testosterone production by the embryonic testes is controlled not by the hypotha- lamic-pituitary system, but by the placental hormone human chorionic gonadotropin (hCG). The absence of MIS in the female embryo permits the Müllerian system to persist. Upon reaching the urogenital sinus, the Müllerian ducts induce the formation of a vaginal plate. Contact of the Müllerian ducts with the vaginal plate also initiates the fusion of the ducts to form the body of the uterus. The Müllerian ducts will form the fallopian tubes, uterus and the upper portion of the vagina. Failure of the Müllerian ducts to develop or fuse completely can cause uterine and cervical anomalies. In the absence of testosterone, the Wolf an system regresses. A vestige of the Wolf an duct, known as Gartner's duct, persists in its length from the ovary to the hymen. Clinically apparent cysts may form anywhere along Gartner's duct. Most of the prostate gland develops from the same primordial area of the urogenital sinus that forms the vaginal plate in the female, making the prostate a homolog of the upper vagina. Mesenchyme in this tissue differentiates into the peripheral zone of the prostate, under the in uence of dihydrotestosterone (DHT). In the presence of a functional fetal testis, DHT is produced locally from testosterone by the enzyme 5α-reductase. The more central tissue in this area, which may be of Wolf an derivation, forms the central and transition zones of the prostate. Cancers of the prostate are most likely to arise from the peripheral zone (Chapter 41). External genitalia Like the primordial gonads, the anlagen of the external genitalia are bipotential. In the 8th embryonic (10th menstrual) week, a urogenital slit, a genital tubercle, two lateral genital folds and two labioscrotal swellings become apparent as precursors to the external genitalia (Fig. 6.2). While differentiation of the internal Wolf an duct system is testo- sterone dependent, the primordial external genital structures require the presence of DHT to differentiate into recognizably male structures. The source of the DHT is testicular testosterone, converted locally to DHT in the primordial external genitalia. In the presence of DHT, the lobes of the prostate gland grow out from the seminal colliculus where the urethra is developing from the bladder. The genital folds fuse to form the penis around the elongating urethra. The labioscrotal swell- ings enlarge and fuse to form the scrotum. Descent of the testes from the abdomen into the scrotum is an androgen-dependent event during which the testes are pulled down- ward by a brous cord anchored to the developing scrotum - the gubernaculum. During development, a peritoneal fold around the Wolf an and Müllerian ducts (destined to eventually become the tunica vaginalis) connects to the genital swelling, and the gubernacu- lum forms as a ridge under the peritoneum. The gubernaculum con- necting the testis to the genital swelling does not grow as rapidly as the remainder of the embryo and hence each testis is progressively pulled down toward the developing scrotum. The testes sit just above the inguinal ring until the last 3 months of pregnancy, at which time they complete their descent through the inguinal canal into the scrotum. After full descent of the testes, the inguinal canal narrows, thereby preventing abdominal contents from herniating into the scrotum. Unlike differentiation of the external and internal genitalia that relies on placental hCG stimulation of testicular androgen production, tes- ticular descent requires fetal gonadotropins. Disruptions in the fetal hypothalamic-pituitary-testicular axis result in failure of the testes to descend properly (cryptorchidism). In the female, the folds of the urogenital slit remain open. The posterior aspect of the urogenital sinus forms the lower two-thirds of the vagina and the anterior aspect forms the urethra. The lateral genital folds form the labia minora and the labioscrotal swellings form the labia majora. The clitoris forms above the urethra. The gubernaculum that forms between the edge of the Müllerian duct and the ovary becomes secondarily attached to the cornua of the uterus as it differentiates. The gubernaculum in the female becomes the ovarian and round ligaments. Female phenotypic differentiation occurs in the absence of androgen and is not dependent on an ovary. Exposure to speci c androgens beginning in the 5th embryonic (7th menstrual) week of pregnancy is critical to the development of a rec- ognizable newborn male phenotype. Fetuses exposed to endogenous or exogenous DHT at this time will undergo male differentiation, regardless of the genetic or gonadal sex. Lack of androgen activity will result in a female phenotype.

MALE REPRODUCTIVE ANATOMY, PHYSIOLOGY AND INFERTILITY

Introduction The chance of a normal couple conceiving is estimated to be 20% to 25% per month, 75% by 6 months, and 85 - 90% by 1 year and so it is inappropriate to pro-ceed along with a work-up after just a few months of trying, unless there is a preex-isting condition that is known to the couple to impact fertility. Most conceptions occur when intercourse takes place within a few days before and including the day of ovu-lation. Studies of couples of unknown fertility status who are attempting to conceive have demonstrated that, although most couples achieve conception within 1 year, approximately 15% of couples are unable to do so. Approximately 20-30% of cases of infertility are caused entirely by a male factor, with an additional 30% to 40% of cases involving both male and female factors. Therefore, a male factor is present in one half of infertile couples. The approach to the evaluation of the infertile male should be similar to that used to evaluate other medical problems. A thorough history should be obtained, with particular attention to those areas that may affect fertility. This should always be followed by a physical examination. An initial series of labora-tory tests completes the basic evaluation - if required based upon the history and physical findings. The results of the history, physical examination, and (sometimes as an adjunct) initial laboratory testing are used to formulate a differential diagnosis that may lead to more specific testing. Many tests are available to evaluate different aspects of male infertility, but not all patients require all tests. The goals of the evaluation of the infertile male are to identify (1) reversible condi-tions; (2) irreversible causes that may be managed by advanced reproductive tech-niques (ART) using the male partner's sperm; (3) irreversible conditions that may not be managed by these techniques and in which the couple should be advised to pur-sue donor insemination or adoption; (4) significant underlying medical pathology; and (5) genetic and/or chromosomal abnormalities that may affect either the patient or his offspring. When possible, specific treatment is directed toward a specific cause. However, both empirical therapies and ARTs, such as intrauterine insemination (IUI) and in vitro fertilization (IVF), may be of value in the absence of known etiologic fac-tors. It is important to remember that therapeutic donor insemination and adoption are treatment alternatives. The infertile couple should be made aware of these op-tions, with the physician playing a counseling role to avoid excessively prolonged, futile treatments. Physiology of the Male Reproductive Axis Male reproduction is controlled by the reproductive axis, which has three tiers of organization: the hypothalamus of the brain, the pituitary gland, and the testis. Hypo-thalamic neurons secrete gonadotropin-releasing hormone (GnRH) into the por-tal system leading to the pituitary. The output of GnRH is influenced by three types of rhythmicity: seasonal, on a time scale of months and peaking in the spring; circadian, resulting in highest testosterone levels during the early morning hours; and pulsatile, with peaks occurring every 90 to 120 minutes on average. The precursors of GnRH neurons migrate to their positions in the hypothalamus from the olfactory placode during embryonic development. In Kallmann syndrome, a condition of congenital hy-pogonadotropic hypogonadism, the GnRH precursor neurons fail to migrate normally and the capacity for hypothalamic secretion of GnRH is not developed. Presentation of olfactory deficiency (anosmia) or other midline defects together with hypogonado-tropic dysfunction is diagnostic of Kallmann syndrome (low FSH, low LH, and low Testosterone with anosmia and consequent failure of virilization at puberty). The two gonadotropins secreted by the pituitary are luteinizing hormone (LH) and follicle-stimulating hormone (FSH). LH stimulates testosterone production by Leydig cells in the interstitium of the testis while FSH, through stimulation of Sertoli cells within the seminiferous tubules, supports spermatogenesis. The rates of testos-terone secretion and sperm production are fine-tuned by a network of negative feed-back relationships between the testis and the upper levels of the reproductive axis. Testosterone and its metabolite, estradiol, suppress secretory activity by the hypo-thalamus and pituitary. Testosterone levels in the testis are often nearly 100-fold greater than that seen in peripheral circulation. Inhibin, a glycoprotein hormone se-creted primarily by Sertoli cells, suppresses FSH secretion. The testis, epididymis, and ductus deferens are responsible for producing and transporting the highly specialized male gamete to the ejaculatory duct. Production of spermatozoa requires many weeks from the initial mitotic divisions through the myriad changes readying it for ejaculation and fertilization. Highlights of this incredi-ble transformation include (1) the initial mitotic divisions of stem cells that result in a daughter stem cell or a daughter germ cell destined to become spermato-zoa; (2) meiosis, within a unique intratesticular environment created in part by Sertoli and interstitial cells, that results in the formation of the haploid gamete; and (3) the dramatic differentiation of the prospective gamete into a special-ized cell ideally suited for transit through the female reproductive tract and, ultimately, fertilization. Although the spermatozoon resulting from this complex process assumes its final shape and size in the testis, it normally achieves the ability to fertilize as well as the capacity for motility only after passing through some portion of the epididymis. The progression of cell types is spermatogonium, primary spermatocyte, secondary spermatocyte, spermatid, spermatozoan. The testis is a specialized structure that functions optimally 2°C to 4°C below body temperature. The process of spermatogenesis takes approximately 64 days in hu-mans and results in a haploid germ cell. Spermatozoa exiting the testis are immotile and have limited capacity to fertilize an oocyte unless assisted reproductive tech-niques are applied. After epididymal transit (which takes 2 to 11 days), sperm are typically motile and capable of fertilization without assistance. Immediately before emission, spermatozoa are rapidly and efficiently transported to the ejaculatory ducts from the distal epididymis. Reproductive History Reproductive medicine has undergone tremendous changes since the 1980s. With the success of high-technology, high-cost procedures, the evaluation of the male is often bypassed. This approach ignores the fact that many causes of male infertility, such as varicocele or a ductal obstruction, are easily and effec-tively treated. In addition, without a full evaluation, significant diseases, such as testicular cancer, pituitary tumors, and neurologic disorders, may be over-looked. Finally, as greater inroads into the genetic causes of male infertility have been made, there has been increased importance placed on the proper evaluation and counseling for the male partner before beginning the ARTs. The duration of infertility, details of prior pregnancies initiated, methods of birth control used in the past, the couple's frequency of sexual intercourse, as well as the timing of coitus should be recorded. It should be determined whether the couple real-izes that ovulation occurs during the middle of the menstrual cycle and that the fe-male is fertile only during this time. Sperm remain viable within the cervical mucus and crypts for 48 hours or longer. Studies have shown that conception may occur when sexual relations take place up to 5 days before ovulation but, owing to the short life span of oocytes, will not occur if sexual relations are performed the day af-ter ovulation. All other present and past medical/surgical issues should be identified. Cryptor-chidism occurs in approximately 1% of male infants age 1 year. It is present at birth in approximately 3% and so many cases resolve spontaneously. The cryptorchid tes-tis, as well as its normally descended mate, may have reduced spermatogenesis but it is not true that all males with a history of cryptorchidism will have infertility. Fertility in a couple is dependent on so many factors - not just sperm density. A history of inguinal hernia repair may suggest blockage of the vas on that side, a history of can-cer and chemotherapy suggests spermatogenic dysfunction secondary to prior toxic therapy, etc. There is no piece of the history that is completely irrelevant. Medica-tions may interfere with spermatogenesis or ejaculatory function and must be deline-ated. For example, sulfasalazine treatment for ulcerative colitis induces reversible defects in sperm concentration and motility. There is evidence that calcium channel blockers cause a reversible functional defect in sperm, interfering with the ability of sperm to fertilize eggs but otherwise not interfering with sperm production or stand-ard semen analysis parameters. Both the testes and the liver are directly affected by ethanol. Testicular atrophy is commonly found in chronic alcoholics. Testicular specimens demonstrate peritubular fibrosis and a reduction in the number of germ cells. The data on the effect of ciga-rette smoking demonstrate an adverse effect on seminal volume, sperm count, motil-ity, morphology, and increased numbers of white blood cells in the semen. Even in in-vitro fertilization cycles, the ultimate pregnancy rate is less when the male is a smoker. The children of men who smoke during conception have a higher rate of certain cancers in childhood. Reproductive Physical Examination The physical examination should be directed toward identifying abnormalities that may be associated with infertility. The patient's habitus as well as the pattern of virili-zation should be noted. Abnormalities of the secondary sex characteristics may indi-cate whether there is a congenital endocrine disorder such as a eunichoid appear-ance associated with Kallmann syndrome. Lack of temporal pattern balding and fine wrinkles on the face may be indicative of an acquired androgen deficiency. Gyneco-mastia is suggestive of either an estrogen/androgen imbalance or an excess of pro-lactin. The penis should be examined for evidence of hypospadias and severe chordee. Both of these may interfere with proper deposition of semen in the deep vagina near the cervix. The scrotal contents should be examined with the patient standing in a warm room to allow for relaxation of the cremaster muscle. The testes should be carefully palpated to determine consistency and to rule out the presence of an in-tratesticular mass. Because the majority of the testicular volume (∼80%) consists of seminiferous tubules and germinal elements, a reduction in the number of these cells is typically manifested by a reduction in testicular volume or testicular atrophy. The dimensions of the testes should be measured. The normal adult testis is larger than 4 × 3 cm in its greatest dimensions or greater than 20 ml in volume for whites and African Americans. It is important to note whether the vasa are present or not and whether the epididymis is full in length and/or firm in consistency (as would occur with a more distal obstruction to sperm flow, e.g vasectomy). The vasa are absent in the conditions of Congential Bilateral Absence of the Vas Deferens (CBAVD) and Cystic Fibrosis (sperm production is normal but there exists no way for the sperm to get into the ejaculate fluid secondary to the absence of much of the ductal system). Examination of the spermatic cords should be performed to identify the presence of a varicocele, hydrocele, spermatocele or lipoma. A varicocele is an abnormal tortuosity and dilatation of the testicular veins within the spermatic cord. A clinical varicocele exists when these dilated veins are palpable on physical examination. Varicoceles are rarely detected before the age of 10 years, with the prevalence increasing to approximately 15% by early adulthood. In contrast, the prevalence of varicoceles in men presenting with infertility is 20% to 40%. Vari-cocele is the most common correctable cause of male infertility. Approximately 90% of varicoceles are left sided. The left testicular vein normally drains directly into the left renal vein, and the right testicular vein drains into the inferior vena cava. The mechanism by which varicoceles affect testicular function remains un-clear. Varicoceles are associated with smaller ipsilateral testes in both adolescents and adults. In addition, ipsilateral testicular growth is often impaired in adolescents with varicoceles. Semen samples from men with varicoceles have demonstrated de-creased motility in 90% of patients and sperm concentrations less than 20 million/ml in 65% of patients. A hydrocele is simply an abnormal amount of fluid within the tunica vaginalis. It is normal to have a small amount of fluid and the only time surgery is undertaken is when the amount is so large that the patient is bothered by the "weight" or the ap-pearance. A spermatocele is a small cyst that arises from the efferent ducts so is found in the region of the head of the epididymis. It contains fluid with spermatozoa within it, is completely benign and does not require surgical intervention unless it is very large and uncomfortable for the patient. Reproductive Laboratory Evaluation After the history and physical examination, the male partner of an infertile couple should have appropriate laboratory testing performed. All patients should have at least two semen analyses. Semen Analysis The semen analysis remains the cornerstone of the laboratory evaluation of the infertile man. Despite this, it is important to realize that the measurement of semen parameters does not necessarily constitute a measure of fertility. Except in cases of azoospermia, the semen analysis does not allow for the definitive separation of pa-tients into infertile and fertile groups. As semen parameters decrease in quality, the statistical chance of conception decreases but does not reach zero. Nevertheless, an accurately performed semen analysis remains an important tool for the evaluation of the infertile man. In most cases, two or three specimens examined over a period of several weeks will give an adequate assessment of baseline spermatogenesis. In those occasional cases in which parameters differ markedly in the initial semen specimens, additional specimens, collected over a 2- to 3-month period, may be ob-tained. The normal range of most diagnostic tests in medicine is determined by using the mean ± 2 standard deviations (SD). Although this may be used to determine "normal" from "abnormal," this does not separate fertile from infertile men. When se-men parameters from populations of fertile and infertile men are compared, there is almost a complete overlap between the two groups. This occurs because fertility is dependent on more than just one semen parameter and on factors affecting both partners. The reference ranges used to interpret the semen analysis are more accurately defined as minimum levels of adequacy. The finding of parameters below these lev-els is suggestive of infertility, and the finding of parameters above these levels is suggestive of fertility. It is important to keep in mind that there are clearly fertile pa-tients with semen parameters below these levels and infertile patients with parame-ters above these levels. The World Health Organization defines the following refer-ence values: Volume: > 2.0 ml pH: > 7.2 Sperm concentration: > 20 × 106 sperm/ml Total sperm number: > 40 × 106 spermatozoa per ejaculate Motility: > 50% with grade A + B motility or >25% with grade A mo-tility Morphology: > 4% by strict criteria Hormonal Assays The purpose of the hormonal evaluation of an infertile male patient is to identify endocrinologic disorders that adversely affect male reproduction and to gain prog-nostic information. Although male reproductive function is critically dependent on en-docrinologic control, less than 3% of infertile men have a primary hormonal etiology. The most common hormonal finding detected on routine testing of infertile men with low/absent sperm counts is an elevated serum FSH. In the presence of normal spermatogenesis, FSH secretion is regulated by negative feedback inhibition by the hormone inhibin, which is produced by the Sertoli cells. Therefore, an elevated se-rum FSH level is indicative of a significant problem with spermatogenesis. Patients with complete testicular failure have inadequate Leydig and Sertoli cell function that results in elevated gonadotropin (both LH and FSH) levels associated with normal or low testosterone levels. Patients with either hypothalamic or pituitary dysfunction have both low serum gonadotropin and testosterone levels as well as absent sper-matogenesis (hypogonadotropic hypogonadism). One of the most common causes of estrogen excess is morbid obesity because fat cells contain the enzyme aromatase that converts testosterone to estradiol. Dysregulation of the leptin/ghrelin axis is thought to also contribute to reduced sper-matogenesis in some obese men. Thyroid function studies do not need to be deter-mined, because these are generally normal unless there is clinical evidence of thy-roid abnormalities. Genetic Studies If the patient is azoospermic (no sperm in a normal volume ejaculate) or has a very low count, a karyotype and Y chromosomal microdeletion assay should be ob-tained. These tests are necessary prior to undertaking any therapy using sperm in the ejaculate or attempting to find sperm in the testis tissue. On karyotypic analysis, Klinefelter syndrome (47,XXY) may be discovered. A phenotypic male with small firm testes, ÷/- gynecomastia, and elevated gonadotropins characterizes the classic form f Klinefelter syndrome. Azoospermia is typically present. Seminiferous tubular scle-rosis is commonly identified on testicular biopsy. However, spermatozoa may be found in the testicular tissue in up to 50% of patients. Plasma FSH levels are usually markedly elevated as a result of the severe seminiferous tubular injury, whereas LH levels are elevated or normal. Total plasma testosterone levels are decreased in 50% to 60% of patients. Other abnormalities that affect sperm production such as 46,XX male syndrome, isodicentric Y chromosomes and translocations all may be identified on karyotype. Along the length of the long arm of the Y chromosome are three regions desig-nated as AZFa, AZFb, and AZFc (AZF stands for "azoospermia factor"). These re-gions contain genes involved in the spermatogenic process and are subject to dele-tion. The vast majority of these deletions occur de novo and are not inherited from the father. Up to 10% of men with non-obstructive azoospermia may be found to have a Y chromosomal microdeletion. Patients with these microdeletions are phenotypically normal, with the only apparent abnormality being a defect in spermat-ogenesis. Deletions in AZFc are the most frequently identified microdeletions in azoospermic and severely oligospermic men. If an AZFa, AZFb, or AZFb/c micro-deletion is present there will be no sperm found on TESE (testis sperm extraction; see below) and surgical intervention is, therefore, not warranted. Men with Congenital Bilateral Absence of the Vas Deferens (CBAVD) have absent vasa and seminal vesicles but normal pulmonary and pancreatic func-tion. However, the underlying genetic etiology of 80-90% of cases of CBAVD is mutations in the Cystic Fibrosis genes (both that inherited maternally and that inherited paternally). The CF genes encode for a protein termed CFTR (cystic fi-brosis transmembrane conductance regulator). Depending upon the severity of the combined set of mutations, a male may present anywhere along a spectrum from full blown clinical CF to simply CBAVD. Therefore, in men with CBAVD it is imperative to perform CF Mutation analysis on both he and his partner before applying treatment (see below) to define for them, as a couple, whether there is a chance of an offspring inheriting CF (if the partner is a CF mutation carrier). Therapeutic Interventions It is always beneficial to the male to be in the best health possible to allow his re-productive system to work at maximal efficiency and reach optimal potential. Hormo-nal manipulation is rarely possible, except in unusual circumstances such as Kall-mann syndrome or pituitary deficiency. Surgical procedures that may be carried out include: Varicocele Repair Treatment of varicocele is directed at ligation or occlusion of the dilated testicular veins. Improvement in seminal parameters is demonstrated in approximately 70% of patients after surgical varicocele repair. Improvements in motility are most common, occurring in 70% of patients, with improved sperm densities in 51% and improved morphology in 44% of patients. Conception rates have averaged 40% to 50%. Testicular Sperm Extraction (TESE) In the azoospermic male with spermatogenic failure, TESE is carried out (if ap-propriate based on the results of the karyotype and Y chromosomal microdeletion assay). Sperm have been reported to be retrieved in over 50% of men with azoo-spermia and Y chromosome microdeletions limited to AZFc undergoing TESE. A similar rate exists for men with Klinefelter syndrome. When a genetic etiology is not uncovered, the rate is approximately 50%. These sperm can be used in conjunction with ICSI to generate pregnancies. Microsurgical Ductal Reconstruction Many azoospermic men are found to have blockages of the vas or epididymis that can be microsurgically corrected/bypassed with great success in order to return sperm to the ejaculate and allow for the possibility of natural pregnancy achieve-ment. The majority of these men have had vasectomies in the past. Other Procedures Many other surgical procedures can be performed to correct an abnormal situation or to harvest sperm such as microsurgical epididymal sperm aspiration (applied in men with CBAVD as there is always a small remnant of the epididymis present and sperm can be retrieved from it for use in conjunction with ICSI), rectal probe elec-troejaculation to obtain sperm in men with ejaculatory failure secondary to spinal cord injury, transverse myelitis, etc, and transurethral ejaculatory duct resection for men with either a partial or complete ejaculatory duct obstruction. Fertility Preservation In postpubertal males about to undergo chemotherapy or radiotherapy, semen cryopreservation should be offered. Testis tissue can be harvested in those post-pubertal males not able to produce an ejaculate or in those pre-pubertal males under an experimental protocol. Finally, The Goal In reproductive medicine we should always be focused on the ultimate goal which is not the achievement of pregnancy but, instead, the birth of a healthy offspring.

44 Cervical cancer

Invasive squamous cell carcinoma accounts for 80% of cervical malig- nancies. Unlike the remainder of the reproductive tract cancers, which are more prevalent in industrialized countries, cervical cancer ranks second in cancer mortality in developing nations. Virtually all cervical cancers are associated with the human papillomavirus (HPV), which is the most common sexually transmitted infection. Squamous cancer of the cervix is unique in that it is a preventable disease when vaccina- tion, proper screening and treatment are available and employed. Like prostatic cancer in men (Chapter 41), cervical cancer typically arises from a precursor lesion, cervical intraepithelial neoplasia (CIN). CIN is asymptomatic and appears to precede invasive carcinoma of the cervix by 5-15 years. Almost all cervical cancer arises in the transformation zone (squamocolumnar junction) of the cervix. Here, the columnar, glandular epithelium of the endocervix meets the squa- mous epithelium of the ectocervix. The anatomic location of the squa- mocolumnar junction changes in response to a variety of factors and is different in young postpubertal girls when compared with postmeno- pausal women (Fig. 44.1). In older women, the transformation zone may be high in the endocervical canal. This makes the early diagnosis of cervical neoplasia more dif cult. Cervical carcinomas can spread in any one of four ways: (i) directly into the vaginal mucosa; (ii) directly into the myometrium of the lower uterine segment; (iii) into the paracervical lymphatics and from there to the obturator, hypogastric and external iliac lymph nodes; and (iv) directly into adjacent structures such as the bladder anteriorly, the rectum posteriorly, or the parametrial tissues and pelvic sidewalls laterally. Lymphatic invasion can occur even when cervical tumors are still small. Hematogenous spread and distant metastases are usually very late manifestations of the disease. Surgical treatment is used for early-stage cervical cancers. A com- bination of radiation and chemotherapy is used for patients with advanced disease and in those who are poor surgical candidates. Epidemiology of cervical cancer The association of sexual activity with cervical cancer was rst identi- ed over 150 years ago when it was noted that the disease was rare in nuns and frequent in prostitutes. Subsequent epidemiologic data have identi ed the onset of sexual activity in adolescence and multiple sexual partners as high-risk characteristics for cervical cancer. Its incidence is higher in low-income women but this effect is not inde- pendent of early sexual activity and multiple sex partners. Smoking is an independent risk factor for the development of cervical cancer. Characteristics of a "high-risk" male partner include men whose previ- ous partner developed cervical cancer, who themselves develop penile cancer or who have not had a circumcision. Epidemiologic data suggesting that cervical cancer behaves like a sexually transmitted disease led to identi cation of HPV as the causa- tive agent. Although it has been identi ed in over 99% of all cervical cancers, HPV infection of the cervix appears necessary but not suf - cient for the development of cervical cancer. This distinction is impor- tant as cervical infection with HPV is very common; however, the majority of these infections are transient. Persistent infection with an oncogenic type of HPV confers an increased risk of developing cervi- cal cancer. Pathogenesis of squamous cell neoplasia of the cervix Because the cervix is so physically accessible, the pathogenesis of cervical neoplasia has been studied extensively. Pathogenesis clearly involves exposure of a vulnerable tissue (the transformation zone) to carcinogens. The squamocolumnar junction is one of six epithelial boundaries present within the lower genital tract. The position of the squamoco- lumnar junction is affected by the hormonal and anatomical changes of puberty, pregnancy and menopause (Fig. 44.1). Prior to puberty, the squamocolumnar junction is at the level of the external cervical os (Chapter 9). With puberty, estrogen-induced changes in the shape and volume of the cervix carry the squamocolumnar junction out onto the anatomic ectocervix. This repositioning exposes tissues previously found in the lower endocervical canal to the vaginal environment. The exposure of the simple mucin-secreting epithelium to the acidic vaginal milieu induces a chemical denaturation of the villus tips of the columnar epithelium. The reparative process that follows eventu- ally produces a mature squamous epithelium. After menopause, the quamocolumnar junction retreats to a position high within the endocervical canal. HPV is a DNA virus that causes epithelial lesions in the skin, cervix, vagina, vulva (Chapter 47), anus and oropharynx. More than 100 types of HPV have been identi ed to date. The HPV infections affecting the genital tract are classi ed according to their oncogenic potential. The highest risk HPV genotypes are 16 and 18, which have been detected in 65% of cervical cancers. Cervical infection with HPV is very common - 80% of all sexu- ally active women will have at least one infection with HPV; however, the majority of these infections are transient. The average duration of infection is 8 months, and 90% of HPV infections in young women will clear within 2 years. It is thought that the local immune response of the host is primarily responsible for HPV clearance; only persistent (greater than 6-12 months' duration) HPV infection puts the cervix at risk for changes that could develop into cancer. Typically, HPV infec- tion persists for greater than 10 years before causing carcinogen- esis. Women with an impaired immune system, such as HIV-infected women, have high rates of persistent cervical HPV infections and cervical neoplasia. Cervical intraepithelial neoplasia (CIN) is the term used to encom- pass all premalignant epithelial abnormalities of the cervix. It has replaced an older terminology that used the terms "dysplasia" and "carcinoma in situ" of the cervix. CIN, although divided into grades, is actually a single neoplastic continuum. The designations CIN1, 2 and 3 re ect the extent of the cellular aberrations within the cervical epithelium (Fig. 44.2). For instance, in CIN1, the lower one-third of the epithelial cells (closest to the basement membrane) lack evidence of differentiation or maturation. This exit from the normal differentia- tion pathway signals neoplastic transformation. Screening tests for cervical cancer The cervical smear or Pap test (named after Dr. George Papanicolaou who developed the test) was designed as a screening test to detect squamous cell abnormalities. Its success is based on the fact that the nuclear abnormalities of neoplastic cervical cells are present in samples that are scraped or exfoliated from the surface of the cervix. In countries where cervical cancer screening with Pap testing is rou- tinely performed, the incidence and mortality rates of cervical cancer have both decreased by 70%. It is likely that the treatment of prema- lignant lesions and the nding of earlier stage cervical cancers have contributed to the decreased incidence and mortality of cervical cancer. HPV tests of the cervix can be used as an adjunct to cervical cytol- ogy screening for women aged 30 years and over. HPV testing for primary screening of younger women is not recommended because of the high rates of transient HPV infections that would be detected. The bene ts of adding HPV testing include: (i) a reliable, readily reproduc- ible measure of the risk of disease; (ii) a high negative predictive value with a single test that allows prolongation of the screening interval; and (iii) increased sensitivity (although lower speci city) compared with cervical cytology in the detection of CIN2-3. Prophylactic HPV vaccination Two prophylactic HPV vaccines based on virus-like particles (VLPs) have been developed. Both provide protection against HPV types 16 and 18 - the causative agent for approximately 65% of cervical cancers worldwide. HPV vaccines prevent the development of HPV 16 and 18 infections, HPV 16 and 18 associated CIN2 or 3, adenocarcinoma in situ and invasive cervical cancer, with 98% ef cacy in young women without prior HPV 16 or 18 infection. Vaccination is recommended for girls who are not yet sexually active as HPV infections rates are very high among adolescents. Interestingly, the mechanism of action of these vaccines is not well understood as the primary mode of natural immunity to HPV is a local immune response and not a systemic response. Cervical adenocarcinoma Adenocarcinoma of the cervix is much rarer than squamous cell lesions. It occurs most often in women during the reproductive years and is frequently associated with HPV type 16 or 18. Although adeno- carcinoma in situ is thought to be the precursor lesion of invasive cervical adenocarcinoma, the timing of progression from precursor to invasion is not well-de ned. Cervical cytology does not reliably detect adenocarcinomas but may detect concomitantly present cervical squa- mous neoplasia; HPV testing should have improved sensitivity for the detection of adenocarcinomas.

Maternal Adapt to Preg

Maternal physiology must adapt in response to a series of demands attendant to pregnancy (Fig. 20.1). The pregnant woman needs to increase her circulating blood volume to supply nutrients to the fetus and to support amniotic uid production. She must clear fetal waste products and protect her pregnancy from systemic perturbations, including starvation or medication ingestion. She must meet fetal and placental nutritional demands for glucose, amino acids and oxygen. The maternal system must adapt to allow for timely onset of labor and for protection of the mother from cardiovascular insults at the time of delivery. It must also prepare to support nourishment of the infant after delivery. All maternal organ systems are affected to some degree. Cardiovascular system During the rst two trimesters of pregnancy, maternal circulating blood volume increases 40% (3500 cm3 expands to 5000 cm3) with the largest expansion occurring during the second trimester (Fig. 20.2). The functions of pregnancy-induced hypervolumia are to meet the demands of the enlarged uterus with its greatly hypertrophied vascular system, to provide nutrients to the growing placenta and fetus, to protect both mother and fetus from impaired venous return in certain postures, and to ensure that the mother does not suffer any adverse effects from the obligatory blood loss at delivery. The increase in plasma volume results from a combination of a modest (10mOsm/kg) decrease in plasma osmolality and from water retention through enhanced activity of the renin-angiotensin system. Placental estrogen increases hepatic production of angiotensinogen, and estrogen and progesterone together increase renal production of the proteolytic enzyme, renin. Renin cleaves angiotensinogen to form angiotensin I, which converts into angiotensin II (AII) in the lung and elsewhere. The increased amounts of AII act on the zona glomerulosa of the adrenal gland to increase aldosterone production. Aldosterone promotes volume expansion through sodium and water retention. Oxygen-carrying capacity must be maintained in the pres- ence of this increase in circulating blood volume. Iron absorption increases to meet the demand for increased hemoglobin during volume expansion. A loss of peripheral vascular responsiveness to AII accompanies the increase in circulating blood volume. AII is a potent vasoconstrictor and loss of AII responsivity results in a drop in maternal blood pres- sure during the early second trimester. This relative hypotension is seen in most pregnant women despite elevated AII levels. Maternal blood pressure slowly rises to prepregnancy levels by the third trimes- ter. Progesterone promotes overall smooth muscle relaxation and is thereby partially responsible for alterations in maternal blood pressure. Production of prostacyclin, the principal endothelial prostaglandin, also increases during pregnancy and has been implicated in the devel- opment of angiotensin resistance. Immediately following delivery of the fetus and placenta, a venous "autotransfusion" from the extremities, pelvis and empty uterus into the right heart occurs. Women with a normal cardiovascular system tolerate this event well but it is a major challenge for women with mitral valve stenosis and Eisenmenger syndrome in whom the increased venous return can result in pulmonary edema and hypoxia. Respiratory system An increase in tidal volume, minute ventilatory volume and minute O2 uptake develops in pregnant women. These changes allow for increased oxygen delivery to the fetus and the periphery. They also cause a mild maternal respiratory alkalosis that is compensated for by increased renal bicarbonate excretion. Progesterone may be responsible for many of these changes. The decrease in plasma bicarbonate shifts the O2 dissocia- tion curve to the left and increases the af nity of maternal hemoglobin for oxygen (the Bohr effect). This decreases the O2 releasing capacity of the maternal blood which is offset by an increase in 2,3-diphos- phoglycerate induced by the increase in pH. This shifts O2 dissociation curve back to the right. Fetal hemoglobin binds O2 at a lower partial pressure than maternal adult hemoglobin. The net result of these changes is to favor transfer of O2 from mother to fetus within the placenta and to facilitate CO2 (waste) transfer back from the fetus to the mother. Many pregnant women have the sensation of shortness of breath in the absence of pathology. This physiologic dyspnea may be the result of decreased pCO2. It is important to note that the blood gas pH of a pregnant woman should be in the alkalotic range with a decrease in pCO2 and bicarbonate and, if not, requires further investigation. Kidney and urinary tract Maternal glomerular ltration rate (GFR) and renal plasma ow (RPF) begin to increase in early pregnancy. By midpregnancy, maternal GFR has increased by as much as 50%; it remains elevated throughout gestation. In contrast, maternal RPF begins to decrease in the third trimester. As a result, the renal ltration fraction increases during the last third of pregnancy. Because of the increased GFR, serum creati- nine and urea are lower in pregnancy than in the nonpregnant state. Creatinine clearance is increased. A 60-70% increase in the ltered load of sodium also accompanies the increased GFR. Progesterone appears to cause some sodium wastage by interfering with normal sodium resorption in the proximal renal tubule. In response, aldosterone increases proportionately to levels that are 2-3 times normal. Renal medullary prostaglandin E2 synthesis also increases in late pregnancy, enhancing sodium natriuresis. The relatively xed renal tubular reabsorptive capacity, in combina- tion with an increased GFR, causes a decrease in the reabsorption of glucose from the proximal tubule of the pregnant woman's kidney. Glucose is therefore detectable in the urine of about 15% of healthy pregnant women. Still, any pregnant woman exhibiting glycosuria should be evaluated for diabetes. The volume of urine contained in the renal pelves and ureters can double in the latter half of pregnancy. The renal collecting system dilates during pregnancy as a result of mechanical obstruction by the pregnant uterus combined with the relaxing effects of progesterone upon smooth muscle. This dilatation decreases the speed of urine passage through the renal system and increases the maternal risk of developing acute kidney infections. Hematologic system Pregnant women are mildly anemic. Maternal hemoglobin production and total red blood cell mass increase during pregnancy in response to elevated erythropoietin production. Maternal vascular volume increases to a greater extent. The result is a mild maternal dilutional anemia that protects the mother from excess hemoglobin loss at deliv- ery. The iron requirements of normal pregnancy must satisfy both maternal and fetal red cell production requirements and total about 1.0g. Most is needed during the second half of pregnancy. Amounts of iron absorbed from diet alone, as well as any mobilized from mater- nal stores, may be insuf cient to meet the demand. Pregnant women develop a modest leukocytosis that can become quite marked during labor and postpartum. The etiology of the mild leukocytosis of early pregnancy is unclear. That seen during labor, however, resembles the leukocytosis associated with strenuous exercise, during which previously sequestered white cells re-enter the active circulation. Pregnant women are hypercoagulable. Increased coagulability develops because of the increased procoagulant synthesis in the liver (Chapter 21). Up to 8% of women will develop a mild thrombocyto- penia (<150 000 platelets/ml). This typically does not result in a bleed- ing diathesis. The mechanism by which the thrombocytopenia develops is unknown. Skin Circulating melanotrophic hormone (MSH) is increased during pregnancy as a result of the increased production of the precursor molecule pro- opiomelanocortin (POM-C) (Chapter 18). MSH causes darkening on the skin across the cheeks (chloasma or pregnancy mask) and darkening of the linea alba, the slightly pigmented line on the skin that runs from the navel to the pubis. Hair may also appear to fall out in clumps because of synchronization of hair follicle growth cycles during pregnancy. Thyroid gland Maternal thyroid hormone is critical for normal embryonic and fetal development. Among the hepatic proteins stimulated by the elevated circulating levels of estrogen in pregnancy is thyroid-binding globulin (TBG). The increased TBG results in a decrease in circulating free T3 and T4 that will stimulate thyroid-stimulating hormone (TSH) production by the pituitary gland, thereby increasing the production of thyroxine by the thyroid gland. The alfa subunit of human chorionic gonadotropin (hCG) also appears to stimulate the thyroid gland, thereby assuring a timely increase in thyroxine production with preg- nancy onset. Interpretation of thyroid tests in pregnancy can be confusing because of the increased TBG. Total T3 and T4 will be elevated as will T3 resin uptake (T3RU), the indirect measure of total thyroxine binding capac- ity. Because of these changes, thyroid testing in pregnancy should rely on measurements of serum TSH and/or free T3 and T4. Gastrointestinal tract Pregnancy is a potentially diabetogenic state. It is a state of relative hyperinsulinism with peripheral insulin resistance. The high mater- nal levels of estrogen, progesterone and human placental lactogen (hPL) cause hypertrophy, hyperplasia and hypersecretion of insulin by the beta islet cells of the pancreas. Still, many pregnant women show prolonged hyperglycemia after meals. In addition, most pregnant women exhibit: (i) exaggerated insulin release in response to glucose infusion; (ii) reduced peripheral uptake of glucose; and (iii) suppressed glucagon secretion. Taken together, these traits characterize insulin resistance. The mechanism(s) for insulin resistance in pregnancy are not well understood. The growth hormone-like activity of hPL may be responsible. In addition, hPL may also promote lipolysis and liberation of free fatty acids that facilitate tissue resistance to insulin. These metabolic changes ensure a continuous supply of glucose for transfer to the fetus. Women at increased lifetime risk for developing type 2 diabetes mellitus (DM) will often develop a condition known as ges- tational diabetes mellitus (GDM). The presence of GDM confers a sevenfold risk of future type 2 DM. The same mechanisms that ensure a continuous supply of fetal glucose produce an "accelerated starva- tion" pro le during fasting. Fasted pregnant women are relatively hypoglycemic and have higher circulating free fatty acids, triglycer- ides and cholesterol. Prolonged fasting or persistent vomiting in preg- nant women can rapidly lead to ketonemia. High maternal levels of circulating estrogens increase the syn- thesis of hepatic proteins. These include procoagulants, bile acids and multiple hormone binding proteins. The procoagulants most mark- edly elevated are factors I ( brinogen), VII, VIII, IX and X. The higher circulating concentrations of clotting cascade proteins protect the mother from excessive blood loss at the time of delivery; however, they also predispose pregnant and postpartum women to venous thrombosis and embolism. Estrogens also stimulate the cytochrome P450 oxidative pathway in the liver. This increases the production of steroid precursors and can dramatically alter drug metabolism. The latter effect necessitates careful monitoring of the maternal plasma drug levels of many commonly used therapeutics. Most notable are the anticonvulsants and antibiotics. The calcium requirements of the developing fetal and neonatal skeleton produce a profound maternal calcium stress during preg- nancy and lactation. Maternal plasma parathyroid hormone (PTH) concentrations rise despite a minimal decrease in circulating free calcium. Intestinal absorption of calcium is enhanced by an increase in circulating 1,25-dihydroxyvitamin D3, the active metabolite of vitamin D. 1,25-(OH)2-D3 increases for two reasons: (i) PTH increases the hepatic synthesis of 25-(OH)-D3, and (ii) the activity of 1α-hydroxylase increases in pregnancy. In nonpregnant women and men, conversion of 25-(OH)-D3 to the 1,25 active form is limited by the activity of 1α-hydroxylase, the nal converting enzyme in D3 metabolism. 1α-hydroxylase is typically present only in the kidney but, in pregnancy, it is produced by both the decidua and placenta. This ensures an adequate amount of active D3 to optimize dietary calcium absorption during pregnancy. If dietary calcium intake is adequate, minimal mobilization of maternal bone calcium occurs. If it is not, fetal and neonatal skeletal mineralization will proceed at the expense of maternal bone density. Progesterone relaxes smooth muscle and thereby affects all parts of the gastrointestinal tract during pregnancy. Gastric empty- ing is delayed, as is movement of digested material along the remain- der of the tract. Gallbladder emptying is slower and bile tends to sludge in the bile duct and common duct. Minor disorders of the gastrointestinal tract are very common in pregnancy. These include nausea, vomiting, constipation and heartburn. Nutritional requirements of pregnancy The nutritional requirements of pregnancy are complex and include water, oxygen, macronutrients (glucose, essential amino acids and fatty acids) and micronutrients (vitamins and minerals). Water is necessary for volume support of the fetus and placenta and for the increase in maternal blood volume (Chapter 20), oxygen for ef cient energy production as ATP, macronutrients for energy production and body growth, and micronutrients for regulating the expression of developmental genes and subsequent tissue functions. Total maternal water retention at term is approximately 6.5 L with approximately 3.5L in the fetus, placenta and amniotic uid and another 3.0 L in the expanded uterus, breasts and blood volume (Table 21.1). Glucose is the predominant source of reduced nicotinamide adenine dinucleotide phosphate (NADPH), which is an essential cofactor for antioxidative enzymes and diverse metabolic pathways in all cell types. Fetal glucose is primarily derived from the uptake and transport of maternal glucose by the placenta. Amino acids serve as building blocks for proteins and as essential precursors of hormones, neurotransmitters, nitric oxide (NO), creatine, glutathione, carnitine and polyamines. Essential amino acids cannot be synthesized by either mother or fetus and must be derived from high quality protein foods or supplements. Long chain fatty acids readily cross the placenta from mother to fetus where they serve as major metabolic fuels. The three most important dietary minerals in pregnancy are calcium, iodine and iron. Besides being a major component of the fetal skel- eton, cytoskeleton and teeth, calcium is also required for calcium activated enzymes involved in digestion, cell-cell adhesion, blood clotting, intracellular proteolysis and NO synthesis. Iodine is required for thyroid hormone synthesis; thyroid hormones, in turn, are required for normal fetal neuronal development. Iodine requirements in preg- nancy increase by ∼30%, -from 150 to 225μg/day. Severe maternal iodine de ciency is associated with cretinism and milder forms of de ciency with impaired cognitive development of the infant. Iron, the most abundant trace element in the body, is a component of hemo- globin, myoglobin and cytochromes. Thus, physiologic levels of iron are necessary for (i) oxygen binding, transport, storage and sensing; (ii) metabolism of glucose, proteins and lipids; (iii) mitochondrial electron transport and ATP production; (iv) DNA synthesis; (v) immu- nity; and (vi) antioxidant activity. Iron requirements in pregnancy almost double from 15 to 27mg/day. Clinical observations and animal studies have demonstrated that vitamins A, B6, B12, D and folate have a major impact on pregnancy outcomes. Pyridoxal phosphate, the active form of vitamin B6, folic acid and vitamin B12 are of signi cance to fetal development because of their role in one-carbon-unit metabolism. Folate is essential to normal embryonic and fetal development and growth. Folate de - ciency in early pregnancy can disrupt neural tube formation; supple- mentation has been shown in clinical studies to reduce the incidence of neural tube defects. The absolute quantities of macro- and micronutrients required during pregnancy in a given woman will vary depending on her pre- pregnancy nutritional status. Anemic women will require more iron. It is estimated that only half of women in developed countries have adequate dietary intake of micronutrients; hence, prenatal supplements are typically recommended. In the underdeveloped and developing world, supplementation is even more critical but often absent. Women with a low body mass index (BMI) will require more calories during pregnancy to support normal fetal growth than women with a normal BMI. The interaction between prepregnancy nutritional status and caloric intake during pregnancy was rst recognized when the off- spring born during a 6-month famine in the Netherlands near the end of World War II were followed into adulthood. The offspring of previ- ously well-nourished women who experience caloric deprivation during pregnancy are at increased risk of being born small for gesta- tional age (SGA) and developing hypertension, coronary heart disease and type 2 DM in adulthood. If the woman is undernourished entering pregnancy, the growth restriction and subsequent abnormalities are more severe and earlier in onset. It is hypothesized that maternal undernutrition leads to development of a "thrifty phenotype" in the fetus that reallocates energy and nutrition to favor development of organs critical to immediate survival. Obesity and metabolic and car- diovascular abnormalities subsequently develop when these individu- als are raised in an environment with a great abundance of high energy foods. Overweight or obese women are at risk of delivering both SGA and excessively large infants who also have an increased risk of obesity in childhood and adulthood. The biologic basis for these fetal origins of adult disease appears to be epigenetic programming, the stable and inheritable alterations of genes through covalent modi cations of their DNA and core his- tones without changes in the DNA sequence. Recent studies indicate that abnormal fetal growth is associated with hypomethylation or hypermethylation of genes involved with the synthesis and regulation of the insulin-like growth factor (IGF) system. Changes in leptin secre- tion and sensitivity that affect eating may also be involved. Immune system The immunology of pregnancy is fairly complicated and may vary fairly signi cantly over the course of gestation. The processes of implantation and parturition are in ammatory in nature, yet maternal immune reactivity over the majority of pregnancy requires a signi - cant level of immune tolerance. The fetus represents a hemi-allograft in a typically immunocompetent host, however, graft rejection usually does not occur. Although the fetus is recognized by the maternal immune system, the incited allo-response is not cytotoxic in healthy pregnancies. Rather, there is an increase in maternal regulatory T helper cell (T reg) number and activity that promotes tolerance to the recognized fetus-speci c antigen. Further, normally cytotoxic CD8+ T cells at the maternal-fetal interface tend to be de cient in the expres- sion of cytolytic molecules such as perforin and granzyme B. Several additional factors are known to be involved in maternal immune tolerance to the developing fetus; many remain to be discov- ered. For example, the fetally-derived placenta does not express classic transplantation antigens that would typically provoke rejection. This includes major histocompatibility complex (MHC) class II and most MHC class I products. Tolerogenic changes in maternal immu- nity do not come without costs. For example, pregnant women experi- ence a higher attack rate and more severe or prolonged disease upon exposure to certain viral pathogens (e.g. varicella/chickenpox). Maternal antibody-mediated immunity is actively transferred to the fetus beginning at approximately 16 weeks' gestational age when receptors for the Fc region of immunoglobulin G (IgG) appear in the placenta.

Proteins of Preg

Placental production of protein hormones The placenta is a very rich source of both protein and steroid hor- mones, only a few of which are unique to pregnancy (Fig. 18.1). These placental hormones are responsible for almost all the maternal and some of the fetal adaptations to pregnancy. Human chorionic gonadotropin Human chorionic gonadotropin (hCG) is a dimeric protein hormone whose structure is closely related to luteinizing hormone (LH) (Chapter 1). It is among the earliest products of the trophoblast cells of the embryo and is necessary to signal the maternal organism that concep- tion has occurred. β-hCG mRNA can be detected in an eight-cell embryo, although intact hCG is not detectable in the maternal blood- stream or urine until 6 days after fertilization. hCG secretion is quan- titatively related to the total mass of trophoblast in the placenta. Its concentration in the maternal serum approximately doubles every 2-3 days in early pregnancy; this can be used as a screen to differentiate normal from abnormal pregnancies. Failure of the hCG concentrations to increase appropriately may indicate an abnormal implantation such as an ectopic (tubal) pregnancy or a nonviable intrauterine gestation. Higher than expected levels of hCG are seen with multiple gestations (Chapter 35) and molar pregnancies (Chapter 45). The major biologic role of hCG is to "rescue" the corpus luteum of the ovary from its programmed demise 12-14 days after ovulation. Because of the close structural relationship of hCG to LH, hCG is able to bind to the LH receptor on luteal cells. hCG can therefore substitute for LH, supporting the corpus luteum when a pregnancy is present. Maintenance of the corpus luteum allows continued secretion of ovarian progesterone after day 14 postovulation and maintenance of the early pregnancy. Surgical removal of the corpus luteum without progesterone supplementation before the 9th menstrual week of preg- nancy will result in a pregnancy loss. Administration of an antiproges- tin such as RU-486 will have similar results. By 9 weeks' gestation (7 weeks after conception), the placenta has typically acquired suf cient cellular mass to supply the large amounts of progesterone necessary for pregnancy maintenance. Progesterone production is taken over by the placenta at this point and the corpus luteum could be removed without adverse effect on pregnancy maintenance. At the end of the rst trimester, hCG also stimulates the fetal gonads to make the steroid hormones responsible for differentiation of the internal and external genitalia (Chapters 5 and 6). Many of the hormones produced within the placenta result from a two-cell system that mimics the interactions between the neuroendo- crine hypothalamus and the pituitary gland (Fig. 18.2a). For instance, gonadotropin-releasing hormone (GnRH) can be synthesized and secreted by the cytotrophoblast cells of the placenta. GnRH from the cytotrophoblast stimulates hCG production by the syncytiotrophob- last. As pregnancy progresses and the placenta becomes the major site of progesterone production, hCG's primary role changes from main- tenance of the corpus luteum to maintenance of progesterone produc- tion by the syncytiotrophoblast. The serum level of hCG re ects this change by increasing to a maximum at about the 9th or 10th menstrual week of pregnancy and then decreasing to a much lower steady state level for the remainder of the pregnancy. Human placental lactogen Human placental lactogen (hPL) is a protein hormone produced exclusively by the placenta. It is structurally related to both prolactin and growth hormone (GH). When the peptide was originally isolated from the placenta, its biologic activity was assessed in animal models, where it has lactogenic activity. Although it was designated as a lac- togen, lactogenic activity has not been clearly demonstrated in the human. Instead, hPL appears to function in metabolism (Fig. 18.2b). Its metabolic activities closely mimic those of GH, with which it shares 96% structural homology. Its effects on fat and carbohydrate metabolism include inhibition of peripheral glucose uptake, stimula- tion of insulin release by the pancreas and an increase in plasma free fatty acids. Prolonged fasting and hypoglycemia increase hPL produc- tion. During pregnancy, blood glucose decreases, insulin secretion increases and peripheral insulin resistance is enhanced. These meta- bolic changes are consistent with the presence of increased GH-like activity, possibly the effects of hPL. Another name for hPL is human chorionic somatomammotropin (hCS). In theory, the decreased maternal glucose utilization induced by hPL would ensure that a steady supply of glucose is available for fetal utilization. There is growing evidence that hPL is involved in regulat- ing glucose homeostasis in the mother so that she can meet the nutri- tional demands of the fetus; however, successful pregnancies have been reported in the absence of hPL production by the placenta. In normal pregnancies, hPL production is directly proportional to placen- tal mass and therefore rises steadily throughout pregnancy. At the end of gestation, over 1g/day of hPL is produced by the placenta. This amount surpasses the production levels of any other protein hormone in either men or women. Other hormones Pituitary growth hormone of either maternal or fetal origin is not necessary for normal fetal growth. In fact, anencephalic fetuses lacking a pituitary gland and the offspring of women with GH de ciency will grow normally in utero. The placenta produces its own variant of GH protein, known as placental growth hormone (PGH). PGH is a candidate hormone for regulating fetal growth. The placenta also pro- duces somatotropin release inhibiting factor (SRIF), also known as somatostatin, that appears to affect HPL secretion by the placenta. The cytotrophoblast cells and the syncytiotrophoblast secrete cor- ticotropin-releasing hormone (CRH), neuropeptide Y (NPY), a CRH secretagogue, pro-opiomelanocortin (POM-C), the precursor to adrenocorticotropic hormone (ACTH) and melanocyte stimulat- ing hormone (MSH). Maternal CRH levels and placental CRH content rise in the last month of pregnancy. Glucocorticoids enhance CRH mRNA production by the placenta, suggesting a positive feed- back system. It is hypothesized that placental CRH and ACTH may be involved in the timing of the onset of parturition. MSH appears to promote maturation of the fetal hypothalamic-pituitary-adrenal axis and has the secondary effect of darkening the maternal skin pigments. MSH induced darkening of the skin on the forehead, nose and cheeks of some pregnant women produces a mask-like appearance known as cholasma. Maternal production of protein hormones Placental hormones exert dramatic effects on the production and activ- ities of nonplacental maternal protein hormones. For example, placen- tal estrogen production stimulates the production of many hepatic proteins. Among these is thyroid-binding globulin (TBG). The increase in circulating TBG in the pregnant woman leaves less thyroid hormone free to circulate. Because free thyroid hormone exerts central negative feedback, this decrease in free thyroid hormone frees the hypothala- mus to release thyroid-releasing hormone (TRH). Maternal pituitary thyroid-stimulating hormone (TSH) secretion increases in response to TRH and the maternal thyroid gland produces enough T3 and T4 to return the circulating levels to normal. Pregnant women therefore have higher levels of TBG, total T3 and T4, but normal amounts of free T3 and T4. This can cause confusion when interpreting thyroid function tests in pregnancy. It also means that pregnant women taking hormone replacement for thyroid gland de ciency often need to increase their dosage to maintain adequate free hormone levels. Pituitary production of prolactin also increases dramatically as a result of estrogen stimulation in the pregnant woman. The number of lactotrophs in the pituitary gland doubles, thereby almost doubling the size and blood supply of the pituitary gland. This increase in size makes the pituitary gland particularly vulnerable to ischemic damage. Therefore, if postpartum hemorrhage and shock are not promptly treated, pituitary gland failure (Sheehan syndrome) may develop.

41 Disease of Prostate

Benign prostatic hyperplasia The prostate is the organ of the body most frequently af icted by disease in males over 50 years of age. The single most common patho- logic process is benign prostatic hyperplasia (BPH). At least 70% of 70-year-old men develop BPH; 40% develop some symptom of bladder out ow obstruction. Epidemiology and symptoms Age is a risk factor for BPH. Data suggesting that black race puts men at increased risk appear to be poorly controlled for socioeconomic status and access to health care. BPH causes urethral obstruction severe enough to warrant medical intervention in about 30% of elderly men. Interestingly, the overall size of the prostate does not correlate with either the presence or the severity of out ow obstruction. The bromuscular hypertrophy that occurs with BPH can partially denervate prostatic and surrounding tissues, leading to urethral irritation and producing frequency and urgency of micturition, urge incontinence and nocturia. BPH is characterized by a gradual increase in both the glandular and bromuscular tissue in the periurethral and transition zones of the prostate that surround the urethra at its origin from the bladder and midsegment, respectively. Nodular hyperplasia is the characteristic microscopic change of BPH. It involves cellular hyperplasia plus associated changes in the architecture of the ducts and acini. Nodular hyperplasia in the transition zone is characterized by large amounts of glandular tissue that arise through budding and branching of pre- existing ducts. This latter type of hyperplastic proliferation is a highly unusual nding in adult human tissues, whether normal or diseased. It is felt that this anomalous development results from a reversion of the tissue to more embryonic behaviors. Pathogenesis Transition and central zones of the adult prostate gland seem to be of Wolf an duct derivation while the peripheral zone arises from the uro- genital sinus (Chapter 6). These diverse embryological origins may explain why BPH occurs within the transition and central zones while prostatic adenocarcinoma originates within the peripheral zone (Fig. 41.1a). The prostate glandular tissue is unique among the internal genitalia in that it requires dihydrotestosterone (DHT) for normal embryologic development and for maintenance. Testosterone acts as a prohormone. It is converted locally to the more potent androgen DHT by 5α-reductase. DHT potency rests on the higher af nity of the prostatic nuclear andro- gen receptor for DHT than for testosterone (see Chapter 2). Differentiation and growth of prostatic epithelium is dependent on androgen-sensitive factors produced in the underlying stroma (embry- ological mesenchyme). Candidate growth factors increase mitosis in prostatic epithelial cells in vitro and include epidermal growth factor (EGF), insulin-like growth factors (IGFs) and basic broblast growth factor (bFGF). Expression of bFGF increases in BPH. Development of BPH requires a normally functioning testis and 5α-reductase. Individuals lacking 5α-reductase have a vestigial pros- tate and never develop BPH or prostate cancer. Men with BPH have raised 5α-reductase activity and possibly an increase in prostate andro- gen receptors, making the "aging" prostate more susceptible to andro- gen stimulation. There may be a protective role for estrogens in BPH. Estradiol production slowly increases in older men when the testes become less responsive to luteinizing hormone (LH) so that more LH is required to maintain androgen production. High LH levels dispropor- tionately stimulate estrogen production. Elevated circulating estrogens increase hepatic sex hormone-binding globulin (SHBG) synthesis and elevations in SHBG reduce concentrations of free testosterone in the circulation. This decreases the amount of testosterone available to be converted to DHT in the prostatic stroma. It is believed that the clinical symptoms of BPH are not caused simply by an increase in urethral resistance due to enlargement of the prostate. Many of the symptoms formerly thought to be secondary to BPH are related to age-related bladder dysfunction, generally referred to as lower urinary tract symptoms (LUTS). Treatment of BPH and LUTS Medical treatment is now the preferred treatment for BPH. It focuses on shrinking the prostate using 5α-reductase inhibitors and on symp- tomatically treating obstructive symptoms with α-adrenergic agents. The latter are effective because of the large proportion of smooth muscle containing adrenergic receptors in BPH. Because the symp- toms of BPH are also caused by bladder dysfunction, antimuscarinic agents that act on bladder muscle receptors are used in select cases. Surgical treatment of BPH includes transurethral prostatectomy (TURP), treatment of BPH tissue using laser technology and micro- wave therapy to the prostate. Prostate cancer Prostate cancer (PCa) is the most common noncutaneous malignancy in the USA and Europe. It will certainly grow in frequency as the population ages. Autopsy series have consistently found incidental PCa in 30-80% of older men. Epidemiology Risk factors for PCa include age, race, positive family history, dietary fat intake and circulating hormone concentrations. African-American men who consume a high-fat diet are at the highest risk for PCa. Asian men residing in the Far East who subsist on a low-fat diet carry the lowest risk. Changes in geography or eating habits profoundly modify these background racial differences. Plasma androgen concentrations at the high end of normal increase PCa risk, as do SHBG or estrogen concentrations at the lower end of the normal range. As with most malignancies, PCa probably occurs due to environmen- tal promoters in genetically susceptible tissues. For PCa, age and family history are predisposing factors and androgen is the promoter. Because the incidence of microscopic PCa appears independent of race and of geography despite very different incidence rates of clinically apparent disease, race may in uence the progression of latent tumors to clinically evident tumors. Modest differences in androgen production among African-American, Asian and white men have been reported. These exposures over a lifetime may explain the in uence of race on PCa. The hereditary form is set apart from the more common form by an earlier age of onset. Hereditary PCa is rare, although positive family history confers signi cant risk for given individuals in that family. Pathogenesis Adenocarcinoma of the glandular epithelium of the peripheral zone of the prostate gland is the most common form of PCa. It results from androgen activity on a tissue with acquired oncogenic potential. Prostatic intraepithelial neoplasia (PIN) is the rst sign of an evolv- ing neoplastic process. It is characterized by proliferation and anapla- sia of the cells lining the ducts and glandular acini of the peripheral zone and disruption of the architecture of the basal epithelial cell layers. Like most malignancies, the prognosis in PCa is determined by the stage and grade of the tumor at detection. Patients with disease local- ized to the prostate have an 80% survival rate at 5 years. The presence of distant metastases at diagnosis signi cantly lowers 5-year survival. PCa spreads locally to the hypogastric and presacral chains of lymph nodes and hematogenously to bone. The interaction between prostatic stroma and epithelium appears to have an important role in the development of PCa (Fig. 41.1b). Dif- ferent stromal growth factors are overexpressed in PCa when com- pared with BPH. Speci cally, the stroma of PCa contains more IGF, EGF and TGF-β, while that in BPH contains more bFGF. DHT and testosterone both stimulate production of EGF and TGF-β by the prostate gland. The androgen dependence of these growth factors probably also accounts for much of the hormonal dependence of the normal prostate gland. Mutations in the ERBB2 oncogene cause increased EGF receptor (EGFR) activity in PCa. Similar ERBB2 mutations are found in breast cancers. In both diseases, the EGFR shifts from its normal position in the basal epithelial layer to the luminal epithelium as the disease progresses from hyperplasia to intraepithelial neoplasia to frank cancer. Hereditary PCa is associated with mutations in the BRCA1 or BRCA2 tumor suppressor genes. Similar gene mutations are also asso- ciated with breast and ovarian cancers. Loss of heterogeneity studies have identi ed several chromosomal loci as potential sites for abnormal tumor suppressor activity in PCa. For instance, in PCa that metastasizes after therapy, there is a gain in genetic material at the site of the androgen receptor gene on the long arm of the X chromosome. The gene for the androgen receptor becomes ampli ed after androgen withdrawal treatment, an adaptation by the tumor that aids its survival under androgen-de cient conditions. This discovery sheds light on the molecular basis for the development of drug resistance by some cancer cells. Prostate-speci c antigen (PSA) is a protease secreted by the pros- tatic epithelium. Small amounts leak across the prostatic acini and into the plasma. PSA determinations may be used as a screening tool for PCa in asymptomatic men although the risk-bene t ratio of this approach remains unclear. Treatment Treatment of locally contained PCa includes surgery, radiation therapy or active surveillance. Surgical treatment involves removing the pros- tate and seminal vesicles in an effort to completely remove all malig- nant prostate cancer cells. With radiation therapy, radiation is delivered to the prostate either externally or internally with seeds placed inside prostate. Active surveillance (following the prostate cancer without speci c treatment) may be used for those men who have small volume disease of the prostate or those who have signi cant comorbidities. In these patients, it is felt that the prostate cancer could grow slowly enough that treatment is not necessary. Other less common treatments for localized prostate cancer include cryosurgery (freezing of the pros- tate) and high-intensity focused ultrasound to the prostate. Treatment of metastatic PCa involves androgen withdrawal, which may be accomplished by orchidectomy (surgical removal of the testi- cles), by treatment with leuteinizing hormone (LH) aka gonadotropin releasing hormone (GnRH) agonists or antagonists (both ultimate- lysuppress LH release, or by treatment with an antiandrogen. Chemo- therapy is used when hormonal withdrawal is not effective; it has modest success in treating metastatic PCa.

Pharmacology of gonadal Hormones and Inhibitors

Estrogens Estradiol (17-estradiol) is the principal and most potent estrogen produced and secreted by the ovary in premenopausal women. Estrone is the primary circulating estrogen after menopause. It is primarily synthesized in adipose tissue from androstenedione secreted by the adrenals and has one third the potency of estradiol. Estriol is the principle estrogen during pregnancy (produced by the placenta); it is a metabolite of estradiol and is less potent than estradiol. A. Estrogen Formulations 1. Estradiol is available in a micronized form for oral administration and can also be administered as a transdermal patch, a vaginal cream or by intramuscular (IM) injection. 2. Ethinyl estradiol, a synthetic estrogen, has less first pass effect than naturally occurring estrogens, and is administered orally. Ethinyl estradiol, and other synthetic estrogens are used in hormonal contraceptives. 3. Mixtures of conjugated estrogens from biologic sources are used orally for hormone replacement therapy (HRT). Premarin, an oral preparation containing sulfate esters of estrone, equilin and equilenin obtained from pregnant mares' urine, is used for HRT. B. Actions 1. Steroid hormones circulate in the plasma bound to albumin or sex hormone-binding protein. The dissociated hormone diffuses through the plasma membrane and binds to its intracellular steroid hormone receptor. Two estrogen-receptor subtypes, and mediate the effects of the hormone. Estrogen-receptor subtype has an N-terminal portion that promotes transcriptional activation; the subtype contains a repressor domain. Receptor subtypes vary in their affinities for different estrogens, chromosomal locations, and tissue distribution 2. The activated steroid-receptor complex interacts with nuclear chromatin to initiate hormone-specific RNA synthesis resulting in the synthesis of specific proteins that mediate many different physiologic functions. Steroid hormones are both receptor and tissue specific; they initiate the synthesis of different RNA species in diverse target tissues. 3. Estrogens also act on membrane receptors on hypothalamic cells to activate G-protein coupled signaling, and on endothelial cells to release nitric oxide and prostacyclin. 4. Estrogen is essential for normal female reproductive development; during childhood it is responsible for growth of genital structures (vagina, uterus, uterine tubes), appearance of secondary sexual characteristics and the growth spurt during puberty. 5. Estrogen has many metabolic effects: o modifies serum protein levels and reduces bone resorption o enhances the coagulability of blood o increases plasma triglyceride levels while reducing LDL cholesterol and increasing HDL cholesterol 6. Continuous administration of estrogen in combination with a progestin inhibits the secretion of gonadotropins from the anterior pituitary. C. Therapeutic Uses of Estrogens 1. Treatment of hypogonadism in young females. Estrogen therapy mimicking the natural cyclical pattern, and usually in combination with a progestin, stimulates the development of secondary sexual characteristics; continued treatment is required after growth is completed. 2. Used in combination with a progestin for treatment of intractable dysmenorrhea or uterine bleeding 3. Hormone replacement therapy (HRT) in women with estrogen deficiency resulting from premature ovarian failure, menopause, or surgical removal of ovaries. 4. Postmenopausal hormone replacement therapy (HRT) o HRT consists of an estrogen component (conjugated estrogens, ethinyl estradiol) and a progestin component (progesterone, medroxyprogesterone acetate) o oral dose is lower than dose in oral contraceptives o relieves hot flashes and atrophic changes in the urogenital tract (atrophy of the vulva, vagina, urethra, and trigone of the bladder). o due to concerns over risks of HRT (endometrial carcinoma) the lowest effective dose for the shortest possible time to relieve symptoms is prescribed o for women with an intact uterus, a progestin is included in the estrogen therapy because the combination reduces the risk of endometrial carcinoma associated with estrogen use alone o estradiol is available as a transdermal patch for treating symptoms o women with only urogenital symptoms (vaginal atrophy) are treated with vaginal administration of estrogen in combination with progesterone 5. HRT for women with premature ovarian failure or premature menopause consists of estrogen in combination with a progestin in a therapy mimicking the natural cyclical pattern that is continued until the age of 50, the average age of menopause. 6. Contraception: estrogens are components of oral contraceptives, parenteral contraceptives and postcoital contraceptives 7. Prevention of bone loss and osteoporosis (other therapies are preferred, such as alendronate and other bisphosphonates) D. Pharmacokinetics 1. Naturally occurring estrogens Estrogens and their conjugated derivatives are absorbed through the GI track, skin, and mucous membranes. Orally administered estradiol is rapidly metabolized and partially inactivated by hepatic metabolism. Micronized estradiol has better oral bioavailability. 2. Synthetic estrogen analogs Ethinyl estradiol is well absorbed after oral administration and more slowly metabolized in the liver and peripheral tissues than endogenous estrogens. Synthetic estrogens are stored in adipose tissue and slowly released providing prolonged action; they also have higher potency than natural estrogens. 3. Metabolism Estrogens are metabolized in the liver and both parent drug and metabolites are excreted into the bile and reabsorbed through the enterohepatic circulation. Inactive products are excreted into the urine. Coadministration with a cytochrome P450 inducer can cause breakthrough bleeding and reduced contraceptive efficacy. E. Adverse Effects 1. Premature closure of the epiphyses of the long bones and short stature when used in treatment of hypogonadism in girls; the dosage must be adjusted carefully 2. Increased risk of endometrial cancer when used as HRT; this effect is prevented by combining the estrogen with a progestin. 3. Small increase in the risk of breast cancer and cardiovascular disease (myocardial infarction, stroke) when used in postmenopausal women as HRT 4. Dose-dependent adverse effects include: nausea, breast tenderness, increased risk of migraine headache, thromboembolic events (deep vein thrombosis), gallbladder disease, hypertriglyceridemia, and hypertension. II. Progestins Progesterone is the major progestin in humans. It is produced in response to luteinizing hormone (LH) in both female and males. In females it is secreted by the corpus luteum primarily during the second half of the menstrual cycle, and by the placenta during pregnancy. In males it is secreted by the testes, and in both sexes it is also secreted by the adrenal cortex. A. Progestin formulations/analogs 1. Micronized form of progesterone is used orally for HRT. 2. Progesterone-containing vaginal creams (estrogen in combination with progesterone) are available for treatment of postmenopausal urogenital symptoms. 3. Synthetic progestins (medroxyprogesterone) have improved oral bioavailability. 4. Older 19-nortestosterone derivatives (norethindrone, norgestrel) have greater androgenic effects than the newer 19-nortestosterone derivatives (norgestimate, desogestrel). B. Actions: 1. High levels of progesterone secreted during the second half of the menstrual cycle o increases basal body temperature o decreases estrogen-driven endometrial proliferation and promotes the development of a secretory endometrium that accommodates implantation of an embryo o inhibits production of gonadotropin, preventing further ovulation o if fertilization takes place, continued progesterone secretion maintains the endometrium in a favorable state for the continuation of the pregnancy and decreases uterine contractions o if fertilization does not occur, release of progesterone from the corpus luteum abruptly ceases, stimulating the onset of menstruation 2. Progesterone (together with estrogen) mediates mammary gland development. 3. Progesterone alters carbohydrate metabolism, stimulates the deposition of fat, and increases the elimination of sodium and water due to competition with aldosterone at the mineralocorticoid receptor. 4. During pregnancy, progesterone inhibits uterine contraction and (together with estrogen) stimulates breast cell proliferation. C. Therapeutic Uses 1. Progestins are used as contraceptives alone or in combination with estrogen. Progesterone is not widely used due to first pass metabolism. Synthetic progestins used in contraception are less affected by first pass metabolism allowing lower doses with oral administration. Synthetic progestins used in contraception include: norethindrone, norgestrel, desogestrel, norgestimate, drospirenone. Synthetic progestins derived from 19-testosterone (norethindrone, norgestrel) have some androgenic activity. Medroxyprogesterone acetate is an injectable contraceptive and the oral form is a common progestin component of postmenopausal HRT 2. Progestins are used in combination with estrogen in HRT to prevent estrogen-induced endometrial cancer. 3. Progestins are used in control of dysfunctional uterine bleeding, treatment of dysmenorrhea, management of endometriosis and infertility. Depot injection of medroxyprogesterone acetate is used for treatment of endometriosis, intractable dysmenorrhea or uterine bleeding. 4. Progesterone is used in assisted reproductive technology to promote and maintain pregnancy. D. Pharmacokinetics Micronized progesterone is rapidly absorbed after oral administration and has a short half-life due to rapid first pass metabolism in the liver. Synthetic progestins are less rapidly metabolized and have half-lives of 1-3 days allowing for once-daily dosing. Medroxyprogesterone acetate administered orally has a half-life of 30 days; subcutaneous or IM injections have half- lives of 40-50 days (providing contraception for ~3 months). E. Adverse Effects 1. Major effects include: headache, depression, weight gain, and changes in libido. 2. May increase the ratio of LDL to HDL cholesterol, and increase blood pressure. 3. Older 19-nortestosterone derivatives (norethindrone, norgestrel) with greater androgenic activity may cause acne and hirsutism. 4. Long-term use of high doses in premenopausal women is associated with a reversible decrease in bone density (a secondary effect due to ovarian suppression and ovarian production of estrogen). III. Antiestrogens and Antiprogestins A. Selective estrogen receptor modulators (SERMs) SERMS are mixed estrogen agonists that have agonist effects in some tissues and act as partial agonists or antagonists of estrogen in other tissues. Agents in this class include tamoxifen, raloxifene, clomiphene 1. Tamoxifen o Tamoxifen is an orally active SERM that is effective in treatment of hormone-positive breast cancer. It acts as an antagonist to prevent receptor activation by endogenous estrogen. Prophylactic use reduces the incidence of breast cancer in women who are at very high risk. o Acts as an agonist at estrogen receptors of endometrium and promotes endometrial hyperplasia and increases the risk of endometrial cancer. o Causes hot flashes (an antagonist effect) and increases the risk of venous thrombosis (agonist effect). o Has more agonist than antagonist activity on bone and prevents osteoporosis in postmenopausal women. 2. Raloxifene o Approved for prevention and treatment of osteoporosis in postmenopausal women. o Has antagonist actions in breast tissue and reduces the incidence of breast cancer in women with high risk. o No estrogenic effects on endometrial tissue. o Causes hot flashes (an antagonist effect) and increases the risk of venous thrombosis (agonist effect)3. Clomiphene o Clomiphene is a nonsteroidal compound used to induce ovulation in anovulatory women who wish to become pregnant. It is a mixture of two geometric isomers that both have mixed agonist and antagonist effects. Clomiphene interacts with estrogen-receptor-containing tissues, including the hypothalamus, pituitary, ovary, endometrium, vagina, and cervix to initiate a series of endocrine events that culminate in a preovulatory increase in the release of LH and FSH from the pituitary and ovulation. Clomiphene has tissue-specific action and both estrogenic and antiestrogenic properties that may participate in the initiation of ovulation. o Adverse effects: headache, nausea, hot flashes, visual disturbances, ovarian enlargement. B. Pure Estrogen Receptor Antagonists: Fulvestrant Fulvestrant is an estrogen receptor antagonist in all tissues. It is used in the treatment of women with breast cancer that has developed a resistance to tamoxifen C. Estrogen Synthesis Inhibitors 1. Aromatase Inhibitors Anastrozole reversibly inhibits the aromatase enzyme required for the last step in estrogen synthesis. Exemestane is an irreversible inhibitor of aromatase. Both agents are used in the treatment of breast cancer. 2. Danazol Inhibits several cytochrome P450 enzymes involved in gonadal steroid synthesis. It also acts as a weak partial agonist of progestin, androgen, and glucocorticoid receptors. Danazol is sometimes used in treatment of endometriosis and fibrocystic breast disease. D. Gonadotropin-releasing hormone analogs and antagonists 1. Leuprolide is a gonadotropin-releasing hormone (GnRH) agonist. With continuous administration, it suppresses gonadotropin (LH and FSH) secretion and thereby inhibits ovarian production of estrogens and progesterone. GnRH agonists are used to suppress endogenous gonadotropin secretion in women undergoing ovulation induction with gonadotropins (controlled ovarian hyperstimulation). 2. Leuprolide is used in short-term treatment (<6 months) of women with gynecological disorders that benefit from ovarian suppression (endometriosis, uterine fibroids; long-term use may cause loss of bone density) and in treatment of precocious puberty in children. E. Antiprogestins: Mifepristone 1. Mifepristone is an orally active steroid antagonist of progesterone and glucocorticoids. It is used as an abortifacient in early pregnancy (used up to 49d after last menstrual period). Administered in combination with misoprostol (prostaglandin E analogue); it achieves complete abortion in 95% of pregnancy. 2. Most common complication is failure to induce a complete abortion. 3. Side effects, likely due to misoprostol include: nausea, vomiting, diarrhea, abdominal cramping, and bleeding associated with passing the pregnancy. IV. Androgens Androgens are steroids that have anabolic and/or masculinizing effects in both men and women. Testosterone and related androgens are produced in the testis, the adrenal and the ovary. Other androgens secreted by the testes are 5-dihydrotestosterone (DHT), androstenedione, and dehydroepiandosterone (DHEA). Testosterone is synthesized from progesterone and dehydroepiandosterone (DHEA) and metabolized to dihydrotestosterone (DHT) in several organs (prostate) which is the active form in most tissues. DHT binds the androgen receptor with greater affinity, and activates gene expression more efficiently than testosterone. Testosterone secretion (from the testes) in adult males is controlled by gonadotropin-releasing hormone from the hypothalamus, which stimulates the pituitary to secrete LH and FSH. LH stimulates steroid synthesis in the testes and FSH mediates spermatogenesis. Testosterone and DHT inhibit the production of LH and FSH through negative feedback to regulate their production. In the plasma testosterone is partly bound to sex hormone-binding protein. Testosterone undergoes rapid hepatic metabolism, and oral administration has little effect. A. Testosterone formulations/analogs 1. Testosterone-containing drug products include: transdermal patches, topical gels, and buccal tablets. 2. Long-acting, lipophilic esters of testosterone (testosterone enanthate, testosterone cypionate) are available that can be administered by intramuscular injection or by transdermal patch. 3. Testosterone and its esters have a 1:1 relative ratio of androgenic to anabolic activity. 4. 17-alkylated androgens (oxandrolone, fluoxymesterone) have less hepatic metabolism and more anabolic activity than testosterone and are orally active. B. Actions 1. Androgens bind to a specific nuclear receptor in a target cell where the hormone-receptor complex binds DNA and stimulates the synthesis of specific RNA and proteins. 2. Testosterone is the active ligand in muscle and liver; in prostate, seminal vesicles, epididymis and skin testosterone is converted (by 5-reductase) to DHT which is the active ligand in these tissues. In brain, liver, and adipose tissue testosterone is converted (by cytochrome P450 aromatase) to estradiol, the active ligand. Testosterone analogues that cannot be converted to DHT have less effect on the reproductive system and a greater effect on skeletal muscle. 3. Testosterone is necessary for normal development of the male fetus and infant. 4. Testosterone is responsible for the major changes in male at puberty: growth of the penis, larynx, skeleton; development of facial, pubic and axillary hair; darkening of the skin, enlargement of muscle mass. 5. After puberty, testosterone maintains secondary sexual characteristics, fertility, and libido and causes male-pattern baldness. 6. Anabolic actions of testosterone include: increased muscle size, and strength and increased red blood cell production, decreased bone resorption. C. Therapeutic Uses 1. Hormone replacement therapy in hypogonadism in males with inadequate androgen secretion due to testicular dysfunction (primary hypogonadism) or to failure of hypothalamus or pituitary (secondary hypogonadism). 2. Stimulation of red blood cell production in certain anemias 3. Treatment of senile osteoporosis 4. Promote weight gain in patients with wasting syndromes (cancer, AIDs) 5. Anabolic effects have been used illicitly by athletes to increase muscle mass and strength and enhance performance. 6. Danazol is a partial androgen agonist that is used in treatment of endometriosis and fibrocystic disease. It inhibits release of FSH and LH and has antiestrogenic activity. Danazol adverse effects include: weight gain, acne, decreased breast size, deepening voice, increased libido, hirsutism. D. Adverse Effects 1. Androgen administration in females causes masculinization (hirsutism, enlarged clitoris, deepened voice, male patterned baldness, and excessive muscle development). 2. In females who are pregnant with a female fetus, exogenous androgens can cause masculinization of the fetus's external genitalia. 3. Excessive doses of androgens in men can cause feminization (gynecomastia, testicular shrinkage, and infertility) due to feedback inhibition of the pituitary and conversion of exogenous androgens to estrogens. 4. In both sexes, high doses of anabolic steroids can cause cholestatic jaundice, elevation of liver enzymes and possibly hepatocellular carcinoma. V. Antiandrogens Antiandrogens are agents that reduce androgen actions by interfering with synthesis of androgens or blocking their receptors. These agents provide important therapy for both benign and malignant prostate disease, precocious puberty, hair loss and hirsutism. A. Receptor Inhibitors: flutamide and spironolactone 1. Flutamide and related agents are nonsteroidal competitive antagonists of the androgen receptor that are used in combination with GnRH agonists (leuprolide) in treatment of advanced prostate carcinoma to decrease the action of endogenous androgens. Adverse effects of flutamide include gynecomastia, hot flashes, impotence. 2. Spironolactone, principally used as a potassium-sparing diuretic, also inhibits androgen receptors and is used in the treatment of hirsutism in women. B. 5-reductase inhibitors: finasteride 1. Finasteride inhibits the metabolism of testosterone to dihydrotestosterone (DHT) in several organs (prostate and hair follicles) which is the active form in these tissues. It is used to treat benign prostatic hyperplasia (reduces prostate size) and at lower doses to prevent hair loss in men. 2. Finasteride is less likely than other antiandrogens to cause impotence and gynecomastia because it does not interfere with the action of testosterone. C. Gonadotropin-releasing hormone analogs and antagonists 1. Leuprolide is a gonadotropin-releasing hormone (GnRH) agonist. With continuous administration, it suppresses gonadotropin (LH and FSH) secretion. In men, inhibition of LH reduces the production of testosterone. 2. Leuprolide and GnRH agonists are available as long-acting depot drug products used in treatment of prostatic carcinoma (first-line therapy). During the first week of therapy it is administered in combination with an androgen receptor antagonist (flutamide) to prevent the tumor flare that may result from the surge of testosterone caused by the initial action of the GnRH agonist. Within several weeks testosterone production falls to low levels. D. Steroid Synthesis Inhibitors Ketoconazole is an antifungal agent that inhibits gonadal and adrenal synthesis of steroids. It is used to suppress adrenal steroid synthesis in patients with steroid-responsive metastatic prostate cancer

. Ch 33: Sexual dysfunction

Prior to 1980, sexual dysfunction of any cause was lumped under the term "impotence" for men and "frigidity" for women. Since then, the classi cation of sexual disorders has evolved and is now based on the physiologically oriented, four-phase model of human sexuality (Chapter 15). This classi cation divides the sexual dysfunction syn- dromes into disorders of desire, disorders of excitement/arousal and disorders of orgasm. The fourth phase of the human sexual response, resolution, is rarely disturbed. Sexual desire disorders include hyper- active and hypoactive sexual drive (libido) and sexual aversion. Excitement phase disorders include erectile dysfunction, dyspareunia and vaginismus. Orgasmic disorders include inhibited orgasm in women and premature ejaculation in men. Sexual desire disorders Normal sexual drive can be thought of as a balance between an "erotic motor," which incites a desire for sexual activity, and a "sexual brake," which keeps urges in check. These excitatory and inhibitory signals appear to converge upon speci c centers in the hypothalamus and limbic system to produce a continuum of sexual desire. It is probably only the polar ends of this range that are abnormal (Fig. 33.1). There is no speci c test for abnormal sexual desire. Instead, the diagnosis of a sexual desire disorder is based on the subjective reporting of abnormal libido that results in individual distress or interpersonal dif culty. The two formally recognized sexual desire disorders are hypoactive sexual desire disorder (HSDD) and sexual aversion disorder. HSDD is de ned as persistently or recurrently de cient (or absent) sexual fantasies or desire for sexual activity. Sexual aversion disorder is the persistent or recurrent extreme aversion to, and avoidance of, all (or almost all) genital sexual contact with a sexual partner. Of patients seeking treatment for sexual desire disorders, 79% have HSDD, 20% have sexual aversion disorder and 1% have hyperactive sexual desires. The causes of sexual desire disorders may be either organic or psy- chosocial. Organic causes include testosterone de ciency, chronic illness, certain centrally acting medications and underlying psychiatric disturbances. Psychogenic causes involve psychologically repressive stimuli such as anxiety, anger, perception of a partner as repulsive, or previous negative sexual experiences. Treatment of the sexual desire disorders is directed rst toward evaluation and correction of any underlying organic problem. Psycho- therapy may be useful in the treatment of sexual desire disorders of nonorganic etiologies. Patients with long-standing sexual dysfunction of organic etiology often develop concomitant psychosocial issues. Individual or group counseling may be extremely useful as adjunctive therapy in these patients. Erectile dysfunction (impotence) Erectile dysfunction (ED) is the recurrent inability of a man to get and keep an erection suf cient for intercourse. ED is mild if a man can usually get and keep an erection, moderate if he can only can get or keep an erection sometimes and complete if he never can. Risk factors for ED include aging, chronic illnesses, a variety of medications and cigarette smoking. It is a common problem among older men; esti- mates report that 50% of 40- to 70-year-old men have some degree of ED. Even more are affected after the age of 70. ED can occur because of vasculogenic, neurogenic, hormonal or psychogenic problems. Eighty per cent of the diagnosable conditions leading to ED are organic. They include, in decreasing order of frequency, atherosclerosis, diabetes, hypertension, medication side effects, prostate surgery, hyperthyroidism and hypothyroidism, hyper- prolactinemia and hypogonadism. While depression is present in 60% of men with ED, it is often unclear whether this mood disorder is the cause or the result of long-standing ED. Successful penile erection involves the activity of autonomic nerves upon the vascular smooth muscle of the penis. Relaxation of penile vascular smooth muscle allows blood to ow into the penis. Here it remains trapped and erection occurs (Chapter 13). Most of the organic causes of ED involve neuropathies of the autonomic nervous system, vascular compromise or, occasionally, testosterone de ciency. Psycho- genic ED involves abnormal central inhibition of the erectile mecha- nism in the absence of demonstrable physical abnormality. The presence of morning erections in a man with ED may suggest a psy- chogenic etiology. Drugs that produce ED are myriad and typically affect the neural re ex pathways necessary for integrating the erection. Examples of medications associated with ED include antidepressants, antipsychotics, sedatives, antianxiety medications, antihypertensives and anticonvulsants. Alcohol and street drugs, including ampheta- mines, cocaine, marijuana, methadone and heroin, can also cause ED. Until recently, treatment options for ED were limited to medication changes, implantable erection devices, intracavernosal injections of prostaglandins and psychotherapy. The discovery that the drug silde- na l can facilitate and maintain erections in impotent men has changed the treatment of ED dramatically. Sildena l was originally tried as an antiangina medication and found to be ineffective. The study subjects were reluctant to turn in their leftover pills and soon the drug's unex- pected side effect was uncovered. Since then sildena l, and related drugs, have been shown to be effective in the treatment of ED and have become widely available for this use. These medications work by inhibiting phosphodiesterase type V (PDE5), a cyclic guanosine monophosphate (cGMP) metabolizing enzyme found predominantly in the penis. Nitric oxide (NO) activates guanylate cyclase in the penis, increasing cGMP, the major mediator of the vascular relaxation neces- sary for penile erection. The longer cGMP stays around, the longer the duration of erection. Blockade of cGMP metabolism promotes and maintains NO proerectile activity. PDE5 inhibitors will not cause erec- tions in the absence of sexual stimuli. Premature ejaculation This is a disorder characterized by ejaculation that occurs with minimal sexual stimulation after penetration and before the man wishes it. This must occur on multiple occasions over time to warrant diagnosis. When making the diagnosis, the man's age, the novelty of the sexual partner and circumstances and his frequency of sexual activity must be taken into account. Premature ejaculation is reported by 10-35% of men seeking help for sexual dysfunction. Unlike ED, which increases with age, premature ejaculation decreases with age. The exact cause of premature ejaculation is unknown. The only demonstrable physiologic correlate of premature ejaculation is that men reporting this disorder ejaculate at a lower level of sexual arousal than do control men. Retrograde ejaculation In men with retrograde ejaculation, semen travels backwards into the bladder rather than out of the penile shaft during ejaculation because the bladder neck does not close appropriately during or after emission. The most common cause of retrograde ejaculation is inability of the bladder neck to close following transurethral prostatectomy (TURP). Damage to penile innervation during prostate surgery, diabetic neu- ropathy and the use of anticholinergic medications are neurologic causes of the condition. Retrograde ejaculation does not require inter- vention unless fertility is desired (Chapter 34). Dyspareunia Patients with dyspareunia experience recurrent or persistent genital pain before, during (the most common) or after sexual intercourse. Of women seeking help with sexual problems, 10-30% report dyspareu- nia, while only 1% of men report the problem. Because dyspareunia is reported far more frequently in women than in men, much more is known about its etiologies and interventional approaches in women. Dyspareunia may re ect a physical or psychogenic problem. Details of whether the symptoms are lifelong or acquired, generalized or situ- ational are helpful in identifying the potential etiology. Organic causes of dyspareunia include the presence of hymeneal remnants, pelvic tumors, endometriosis, pelvic in ammatory disease and vulvar vesti- bulitis. Hypoestrogenic states associated with menopause, the early postpartum period, use of very low dose oral contraceptives and prior treatment with chemotherapy may also cause dyspareunia. Psychoso- cial problems that result in dyspareunia may include poor self-esteem and body image, guilt and prior sexual abuse or trauma. Interpersonal factors between the couple, including anger, distrust and poor com- munication, may also be responsible. Treatment of dyspareunia is directed toward evaluation and correc- tion of underlying organic problems. Psychotherapy may be useful in the treatment of dyspareunia of nonorganic causes. It may also be useful as concomitant therapy for those with primary organic causes. Vaginismus Women with vaginismus experience recurrent involuntary spasms of the pelvic muscles of the outer third of the vaginal barrel of such severity that intercourse is painful or impossible. Typically, these occur in anticipation of intercourse or during penetration. In some women with severe vaginismus, spasms can also occur during a pelvic examination or tampon insertion. Vaginismus occurs in 0.5-5% of women. There are signi cant inter- cultural differences. Lifelong vaginismus is a rare clinical entity in North America and most of Western Europe. It is relatively common in Ireland, Eastern Europe and Latin America. It is the most commonly reported cause of unconsummated marriages. Like dyspareunia, vaginismus can have either an organic or psycho- social etiology. The organic bases of the disorder are the same as those of dyspareunia. In fact, most experts believe that vaginismus begins as dyspareunia and escalates to vaginismus through a classic condi- tioning process. In this view, a woman rst has pain on intercourse (unconditioned stimulus) and this leads to a natural self-protecting tightening of the vaginal muscles (conditioned response). Over time, stimuli associated with vaginal penetration can become conditioned stimuli and provoke the conditioned re ex muscle spasms. In severe cases, conditioned stimuli can even include thoughts of sexual intercourse. Not all cases of vaginismus are classically conditioned from an organic cause. Many psychosocial contributors have been suggested, including guilt, religious constraints, responses to a partner's sexual dysfunction, prior sexual trauma, concerns about sexual orientation and fears of pregnancy, sexually transmitted diseases and trauma. Like dyspareunia, treatment of vaginismus is directed toward evaluation and correction of any underlying organic problem, and psychotherapy.

. Ch 5: Gonadal development in the embryo

Role of sex chromatin in reproductive development All mammalian females are homogametic and represent the "default" pathway in sexual differentiation. Homogametic describes the sex whose cell nuclei contain two similar sex chromosomes. While this characterizes mammalian females, the homogametic sex is male in butter ies, birds and some amphibians and shes. In humans, all normal oocytes from genetic females will carry 22 autosomes and an X chromosome (22X). Mammalian embryos of both genetic sexes are bathed in relatively large amounts of placental estrogen during devel- opment. In the absence of speci c factors regulated by a single gene on the Y chromosome, embryos will develop into a female phenotype. The human female, like all mammalian females, represents the funda- mental or undifferentiated phenotypic sex. All mammalian males are heterogametic. They produce gametes with both 22X and 22Y chromosome complements. Males are consid- ered the differentiated phenotypic sex. With few exceptions, any indi- vidual that carries a speci c piece of the Y chromosome will develop a testis and a male phenotype. This segment of the Y chromosome has been called the sex-determining region of the Y chromosome (SRY) (Fig. 5.1). Speci c instruction from the SRY region of the Y chromo- some directs the undifferentiated gonad to become a testis. Without the presence of SRY, a fetus will develop along the default or female phenotypic pathway. The Y chromosome is much smaller than the X and very little of its DNA is available for RNA synthesis. Many of the genes that control testicular development from the undifferentiated gonad are therefore located on other chromosomes, including autosomes and the X chro- mosome. However, the Y chromosomecontains a speci c, single-copy gene that determines testicular differentiation. This gene is located on the short arm of the chromosome within SRY and appears to activate genes on other chromosomes. Evidence for the importance of SRY comes from both clinical and experimental research results. Examination of the DNA sequences of women with XY karyotypes has revealed that a single locus within the Y chromosome must be present and intact for an individual to have a testis. Absence of, or damage to, this DNA sequence in individuals with an otherwise intact 46XY male chromosomal content results in ovarian development and a phenotypic female. Likewise, examination of the DNA sequences of phenotypic men with XX karyotypes will reveal the aberrant presence of SRY sequences. Gonadal differentiation Gonadal development begins in the human at the 4th embryonic (6th menstrual) week in parallel with the formation of the ventral body wall. The rst step in gonadal development is the migration of undif- ferentiated primordial germ cells from their site of formation in the yolk sac. These germ cells arise from the endoderm lining the yolk sac; they detach themselves and migrate dorsally along the yolk stalk, midgut and dorsal mesentery to reach the genital ridges. The genital ridges lie on the medial aspect of the mesonephric ridge that will contribute to the developing kidney. Over the next 2 weeks the pri- mordial germ cells mitose repeatedly, forming a vast population of precursor gametes. Failure of these germ cells to develop and populate the genital ridges at this time will result in complete failure of gonadal formation. When germ cells reach the coelomic epithelium lining the genital ridge, cellular contact causes the coelomic epithelia to differentiate into a primitive germinal epithelium. The germ cells become embed- ded in the primitive germinal epithelium during this process of dif- ferentiation. This combination of germinal epithelia and germ cells forms the sex cords. The connection of the sex cords to the coelomic wall (gonadal surface) is maintained at this point. The gonads are now histologically distinct, bipotent organs that may become testes or ovaries (Fig. 5.2). Inappropriate or incomplete developmental signals during this stage can result in the rare condition of hermaphroditism. True hermaphrodites have both ovaries and testes and are extremely rare in humans. In a genetic male, gene products directed by activation of the SRY locus on the Y chromosome now cause the undifferentiated sex cords to enlarge, split and begin to form the primitive testis. Subepithelial mesenchyme arises between the germinal epithelium and the sex cords and cuts the cords off from the gonadal surface. The sex cords are now housed within the inner portion of the gonad - the testicular medulla. The primordial germ cells within the sex cords begin to differentiate into immature sperm cells called spermatogonia. The supporting sex cord cells form precursor Sertoli cells. Ovarian differentiation occurs about 2 weeks later than testicular development. Initially, the sex cords of the developing ovary continue to proliferate while maintaining their connection with the gonadal surface. The germ cells begin to differentiate into primordial oocytes called oogonia within follicles. The epithelium surrounding the oogonia differentiates into granulosa cells. Subepithelial mesen- chyme then invades the gonad and breaks up the sex cords, isolating the follicles. This mesenchyme will become the ovarian stroma. Unlike the testis, developing ovarian gametes are now housed in the outer portion of the gonad - the ovarian cortex. The ovary and testes can be histologically distinguished from each other by the 8th embryonic (10th menstrual) week of pregnancy. The progeny of the germinal epithelium are now apparent as Sertoli cells in the male and granulosa cells in the female. Similarities between males and females in the endocrine function of these cells stem from their common ancestry. The mesenchyme arising beneath the germinal epithelium in the testis is the anlagen of testicular interstitial cells, also known as Leydig cells. The mesenchyme arising beneath the germinal epithelium of the ovary is the anlagen of ovarian stroma or thecal cells. Functional similarities in these two cell types will also be seen in the mature glands. Once the undifferentiated gonads begin to develop into either ovaries or testes, the remainder of sexual differentiation is dependent on secretory products of the testes only. In the absence of these speci c testicular secretions, the phenotype that develops is completely female. The ovary and its secretory products do not contribute to the develop- ment of the uterus, fallopian tubes, vagina or vulva.

Steroids of Prep

Steroid hormone production during pregnancy requires coopera- tion among maternal, fetal and placental organs and enzyme pathways (Fig. 19.1a). The fetus and the placenta each lack key steroidogenic enzymes and would be unable to synthesize certain steroid molecules if they existed in isolation. Interplay among fetus, placenta and the mother are essential to produce the full spectrum of steroidal products necessary for pregnancy maintenance. For example, the fetal adrenal gland has diminished 3β-hydroxysteroid dehydrogenase: Δ4-5 isomer- ase activity and therefore it secretes large amounts of the progesterone precursors, pregnenolone and dehydroepiandrosterone, and very little progesterone (Chapter 2). Because the fetus can synthesize so very little progesterone directly, it obtains its supplies from the placenta. Because the syncytiotrophoblast layer of the placenta lacks a key enzyme, it cannot synthesize cholesterol from circulating acetate. To synthesize progesterone, the placenta requires cholesterol or pregne- nolone from maternal or fetal sources. The vast majority arises from the maternal system and is transported to the placenta in the form of low density lipoprotein (LDL) cholesterol. In contrast to the mother and placenta, the fetus has a remarkable ability to rapidly conjugate steroids with sulfates. Sulfation creates less potent steroids with more rapid clearance, characteristics that allow the fetus to be safely exposed to the high levels of circulating steroids seen during pregnancy. The fetal liver can ef ciently hydroxylate steroid precursors and thereby provides the placenta with those hydroxylated steroids necessary for estrogen production. The placenta has almost no 17α-hydroxylase or 17,20 desmolase activity. For this reason, the precursors of the estrogens produced by the placenta must be supplied by the fetal or maternal systems. The placenta exhibits a robust ability to cleave sulfate groups from steroids. Placental sulfa- tase is integral to the formation of estrogens from fetal sulfated precur- sors. As the placenta lacks 17-α hydroxylase, all estriol produced during pregnancy arises from 17-α hydroxylated fetal precursors. Progesterone The corpus luteum of the ovary supplies progesterone until about 10 weeks' gestation. This supports pregnancy until placental progesterone production takes over in weeks 7-9 of gestation. The levels of 17α-hydroxyprogesterone produced by the corpus luteum rise in early pregnancy but fall by 10 weeks' gestation. After that time, placental production of progesterone dominates the maternal system and the placenta exhibits almost no 17α-hydroxylase activity. Unlike other steroid-producing glands, the placenta lacks the enzymes to form cholesterol from acetate; therefore, progesterone produced by the syncytiotrophoblast is dependent on maternal choles- terol. hCG produced by the placenta supports the synthesis and secre- tion of progesterone within the placenta. Estrogens may also promote progesterone production by stimulating cholesterol uptake by the pla- centa and placental enzymatic conversion of cholesterol to pregne- nolone. As a result, very large amounts of progesterone are produced and secreted by the placenta into the maternal bloodstream. This pro- gesterone is active locally within the uterus, where it maintains the decidual lining of the uterus and relaxes the smooth muscle cells of the myometrium. It also has peripheral effects upon vascular smooth muscle and other organs that must adapt to the demands of pregnancy (Chapters 20 and 21). Estrogens The placenta can ef ciently aromatize androgen precursors to estrogens because it expresses abundant amounts of the enzyme aromatase. All three of the major estrogens, estrone (E1), estradiol (E2) and estriol (E3), are produced in the placenta; however, their androgen precursors arise from different sources (Fig. 19.2). Because placental aromatase is so abundant, it is not rate-limiting. Therefore, the relative amounts of each estrogen produced are determined by the amounts of substrate delivered to the placenta. The major androgen precursor for placental estro- gen production is dehydroepiandrosterone sulfate (DHEA-S). DHEA-S is an adrenal androgen and the majority supplied to the pla- centa originates in the maternal adrenal gland. In the placenta, DHEA-S is converted to DHEA by the abundant placental sulfate-cleaving enzyme, sulfatase. Maternal DHEA is then converted to androstenedi- one, then testosterone and nally to estrone and estradiol (Chapter 2). A very small amount of fetal DHEA-S is also utilized by the placenta to produce estrone and estradiol. However, the majority of fetal DHEA-S is converted to estriol in the placenta. To accomplish this, most of the fetal DHEA-S rst undergoes 16-hydroxylation in the fetal liver. When the fetal 16α-OH-DHEA-S reaches the placenta, the pla- cental sulfatase cleaves the sulfate side chain. 16α-OH DHEA is further metabolized and aromatized within the placenta to estriol. Estriol, which is not produced by the human ovary, is a relatively weak estrogen, but when produced at the high levels seen in pregnancy it can have dramatic estrogenic effects. The amount of estriol produced by the placenta far exceeds that of estrone and estradiol, making placental estriol of fetal origin the major placental estrogen. Like progesterone, most of the estrogen produced by the placenta is found in the maternal compartment (uterus and bloodstream). Unlike its other estrogenic activities, estriol appears to be as effective as estradiol and estrone in increasing uteroplacental blood ow. Its relatively weak estrogenic effects on other organ systems make it highly effective in this single important pregnancy function. Its unique production from a fetal substrate also permits fetal regulation of utero- placental blood ow. Uteroplacental blood ow is an important deter- minant of fetal growth and well-being. Fetal adrenal physiology By about 9 weeks' gestation, the fetal adrenal gland has developed an inner fetal zone and a very thin outer de nitive zone. The latter will develop into the adrenal cortex in the adult. Approximately 80% of the gland is composed of the inner fetal zone. The fetal adrenal gland functions independently of adrenocorticotropic hormone (ACTH) until nearly 15-16 weeks' gestation. During this pre-ACTH phase, the fetal adrenal is thought to respond to hCG. After this time, it is control- led by ACTH secreted by the fetal pituitary gland. The fetal adrenal gland increases in size until about 24 weeks' gestation. It undergoes another impressive growth spurt at 34-35 weeks. 3β-hydroxysteroid dehydrogenase activity is limited in the fetal zone and therefore its major secretory products are DHEA and DHEA-S. These serve as the major substrates for circulating maternal estrogens. In fact, circulating maternal estrogen levels re ect the size of the fetal adrenal. Fetal ACTH control of its adrenals is assured by the presence of high levels of estrogen during pregnancy (Fig. 19.1b). Placental estrogens activate placental 11β-hydroxysteroid dehydrogenase. This in turn metabolizes maternal cortisol, allowing little to reach the fetal circulation. Maternal adrenal function and salt metabolism During pregnancy, the zona fasciculata of the maternal adrenal gland increases in size at the expense of the other adrenal cortical zones. In response, maternal glucocorticoid secretion increases, with signi cant elevations in maternal levels of circulating cortisol. Elevated estrogen levels also drive an increase in the production of cortisol-binding globulin. Still, an increase in the level of circulating free cortisol accompanies the increase in total cortisol. An increase in maternal plasma renin activity and angiotensinogen production results in an increase in plasma aldosterone levels during pregnancy. This results in elevated sodium retention and is partially responsible for the notable increase in maternal vascular volume.

7 Gross Anatomy of Male

Testes and epididymis scrotum is basically a specialized dermal pouch that protects the testis and epididymis from physical injury and aids in heat regulation of the testes. Spermatozoa are very heat sensitive. Because the testes and epididymides are outside the body cavity, intratesticular temperature is typically lower than in the abdomen. Disorders of urogenital devel- opment that result in testicular retention within the abdominal cavity or inguinal canal can have dramatic effects on future fertility and increase the risk for testicular tumors (relative risk 3-8). Most of these are seminomas (Chapter 40). Vas (ductus) deferens and seminal vesicles The vas deferens is a direct continuation of the epididymis. It is a 45-cm-long structure that begins at the lower end of the epididymis and ascends along the posterior aspect of the testis in loose coils. After leaving the back of the testis, the vas deferens traverses the spermatic cord into the abdomen. The vas deferens may be felt as a rm hard cord on the posterior aspect of the spermatic cord as it traverses the scrotum toward the super cial inguinal ring. After crossing into the abdomen, the vas deferens curves medially across the external iliac artery toward the pelvis. From there, it crosses the obturator nerve and vessels and the vesicular vessels. The vas deferens then crosses over the ureter to meet the duct of the seminal vesicle. Together, the vas deferens and the duct of the seminal vesicle form the ejaculatory duct that opens into the prostatic portion of the urethra. The ejaculatory duct is short (2.5 cm) and lies very close to its companion contralateral duct as they pass forward through the prostate. The seminal vesicles are a pair of hollow, sacculated structures located at the base of the bladder in front of the rectum. Each vesicle is about 5 cm long and more intimately connected to the bladder than to the rectum. During embryonic development, the seminal vesicles form as diverticula of the vas deferens. The structures share common blood and lymphatic supplies. The testes are a pair of oval, slightly attened bodies measuring about 4 cm in length and 2.5 cm in diameter. Together with the epididymides, they lie in the scrotum, an extra-abdominal sac just below the penis. The walls of the cavity in which the testes and epididymis reside are known as the tunica vaginalis. The tunica vaginalis forms from intra- abdominal peritoneum that migrates into the primitive scrotum during development of the male internal genitalia. After migration of the testis into the scrotum, the channel down which the testis has moved (proc- essus vaginalis) is obliterated. The epididymis is a comma-shaped structure that clasps the poste- rolateral margin of the testis. It is formed from the duct of the epidi- dymis, an irregularly twisted tube. The epididymal duct is about 600 cm long. It begins at the top of the testis as the head of the epidi- dymis. After an extraordinarily tortuous course it ends as the tail of the epididymis, then becomes the vas deferens (Fig. 7.1). The testicular arteries supply blood to the testes and epididymides. These arteries arise from the aorta just below the renal arteries. The testicular arteries end in a dense vascular plexus, the pampiniform plexus, which courses just under the tunica vaginalis surrounding the testes. The plexus drains into the testicular veins. The pampiniform plexus dissipates heat out of the scrotum by vasodilatation and thereby has an important role in temperature regulation of the testes. Like the ovarian veins, the right testicular vein empties into the inferior vena cava, and the left testicular vein into the left renal vein. Lymphatic drainage of the testes is to the para-aortic nodes. All the blood and lymph vessels to the testis and epididymis are bundled in a structure known as the spermatic cord. This structure also contains the vas deferens and any remnants of the processus vaginalis. The spermatic cord enters the scrotum from the abdomen through the inguinal canal. The testis is the site of spermatogenesis and sex steroid production in the male. The epididymis is the site of nal sperm maturation. The Blood supply to the vas deferens and seminal vesicles is mainly from the inferior vesicular artery. The artery accompanies the vas deferens into the scrotum where it anastomoses with the testicular artery. Lymphatic drainage is to the internal and external iliac nodes. The vas deferens functions in sperm transport. The seminal vesicles produce approximately 50-60% of the volume of the seminal uid. Important seminal vesicle-derived semen components include fructose and prostaglandins. Prostate gland The prostate is a partly glandular, partly muscular organ that surrounds the beginning of the male urethra, rmly af xed by a connective tissue sheath just behind the symphysis pubis. The organ is about 2.5 × 3.5 × 4.5cm. The median lobe of the prostate, histologically referred to as the transition zone, is wedge-shaped, directly surrounds the urethra and separates it from the ejaculatory ducts. When hyper- trophied, the median lobe may obstruct the ow of urine. Median lobe hypertrophy occurs commonly in elderly men. The anterior prostate is composed mostly of bromuscular tissue. The glandular tissue of the prostate is situated at the sides of the urethra and immediately posterior to it. This glandular tissue is sub- divided into a central and peripheral zone based on embryology (Chapter 6) and histology (Chapter 8). The peripheral zone is much larger than the central zone and composed of about 50 incompletely de ned lobules. Each lobule contains minute ducts that empty directly into the urethra just above the ejaculatory ducts. The blood supply to the prostate gland is variable, but most com- monly arises from the common origin of the internal pudendal and inferior gluteal arteries off the internal iliac (hypogastric) arteries. The veins draining the prostate are wide and thin-walled, forming a plexus that communicates with the plexus draining the bladder. Both drain into the internal iliac veins. The prostatic plexus also communicates with the vertebral venous plexuses; therefore, a tumor in the prostate may give rise to secondary growth in the vertebral column. Lymphatic drainage of the prostate follows that of the seminal vesicles and bladder neck into the iliac chain of nodes. All the muscular tissues in the vas deferens, prostate, prostatic urethra and seminal vesicles are involved in ejaculation. Prostate secretions contribute ∼15% of the volume of the seminal uid. Impor- tant prostate-derived components include acid phosphatases, zinc, citrate and proteases that aid in semen liquefaction. Liquefaction enables sperm to escape the very viscous initial ejaculate. Penis The penis is composed chie y of cavernous (erectile) tissue and is traversed by the urethra. The posterior surface of the accid penis is nearest the urethra and the opposite, more extensive surface is dorsal (Fig. 7.2). Most of the erectile tissue of the penis is arranged in three longitudinal columns: the paired corpora cavernosa and the single median corpus spongiosum. The tip of the penis is called the glans. The glans of the penis also contains erectile tissue and is continuous with the corpus spongiosum. The glans is covered with a retractable folded layer of thin skin, called the prepuce or foreskin. Although it is not typically indicated medically, the operation of circumcision removes the foreskin and is still widely practiced in some societies. The internal pudendal arteries supply blood to the penis, entering the organ on its dorsal surface and penetrating deeply into the erectile tissue of the corpora cavernosa. Veins draining the penis enter the prostatic plexus either directly or through the dorsal vein of the penis. Erection of the penis occurs when the extensive cavernous spaces of the corpora cavernosa and corpus spongiosum ll with blood. Engorgement of the penis inhibits venous return and allows maintenance of erection. Innervation of the penis is critical for its erection. Penile nerve supply is derived from the pudendal nerve (2nd, 3rd, 4th sacral nerves) and from the pelvic autonomic plexuses. The lymphatic drainage of the penis is into the medial group of super cial inguinal lymph nodes. The function of the penis is penetration. Penetration of the vagina of the female allows deposition of semen near the uterine cervix.