OB Ch 56 Placenta

Chorion Frondosum

(fetal side of placenta) -Trophoblastic tissue and decidua -forms area for maternal and fetal circulation

around the gestational sac on opposite side of implantation

-Chorion Laeve

-Types of GTD

-Complete -no fetal tissue -Partial -coexistent mole/fetus -Choriocarcinoma -Invasive Mole

Small placenta causes:

-IUGR -intrauterine infection -aneuploidy -pre-eclampsia -chronic hypertension -placental insufficiency -cigarette smoking

Risk Factors of Placental abruption

-Maternal hypertension is seen in approximately 50% of severe abruption and is associated with fetal demise -Previous hx of abruption -short umbilical cord -uterine anomaly -fibroid (myoma) -abdominal trauma -Placenta previa -Tobacco use -cocaine use

Amniotic Sac and fluid

-Originally produced by diffusion of maternal blood across amnion -1st trimester fetus begins to excrete urine

Placenta Position

-Posterior -Anterior -Lateral (right or left) -Fundal -Combination

Functions of the placenta:

-Protection -Nutrition -Respiration -Placenta acts as fetal lungs -Excretion -Storage -Hormonal Production -hCG, estrogen, progesterone

Large Placenta causes:

-Rh sensitivity/maternal diabetes most common cause of placentomegaly -maternal anemia -feto-maternal hemorrhage -chronic uterine infections -twin to twin transfusion -congenital neoplasms -fetal malformations

-Implantation of the placenta

-anterior, fundal, posterior or lateral wall of the uterus -previa may occur if implanted low

-Sonographic findings of chorioangioma

-circumscribed solid/complex mass protruding from the fetal surface of the placenta -hyperechoic or hypoechoic -well rounded

Fibrin Deposition sono appearance

-hypoechoic -differential considerations -venous lake or subchorionic hematomas

symptoms of GTD

-increased hCG levels -hyperemesis gravidarum -vaginal bleeding -uterine size larger than dates -pre-eclampsia

signs and symptoms of Vasa Previa

-painless vaginal bleeding -palpation of vessels through the cervix -fetal heart rate decelerations or bradycardia -spontaneous membrane rupture

-Complications to fetus w/ chorioangioma

-polyhydramnios -hydrops -anemia -cardiomegaly -IUGR -fetal demise -premature delivery with large tumor

Complications of placenta previa

-premature delivery -hemorrhage- maternal postpartum -increased risk of placenta accrete -IUGR

Retroplacental

-results from rupture of spiral arteries -high pressure bleed -associated with hypertension and vascular disease -the hematoma is between the placenta and uterus -if it remains retroplacental, patient may have no visible bleeding

Marginal

-results from tears of the marginal veins -low pressure bleed -hemorrhage dissects beneath the placental membranes and is associated with little placental detachment -subchorionic hemorrhage accumulates at site separate from placenta

Placental Grading -Grade 0-1 and 2nd trimester; ___ to _____ weeks -smooth chorionic plate, homogeneous texture with no calcifications -Grade 1- ___% reach this point; ____ weeks -scattered calcifications -Grade 2- ____% reach this point; ____ weeks -calcification of the_______ -more pronounced calcifications in the placenta -subtle indentions extending into placenta -Grade 3- ____% reach this point; ____ weeks -______ (lobulated appearance) -calcifications more prominent throughout

12, 28-30 wks 40%, 28 wks 45%, 36 wks , basilar plate 15%, 38 wks, indentions

The Umbilical Cord -Forms during 1st ____ weeks -________ -surrounded by mucoid connective tissue -Intestines herniate into cord until approximately ___-____ weeks -3 Vessel -1 ______- oxygenated -2 _____ -deoxygenated -Ductus Venosus -________

5, 10-12, vein, arteries, ligamentum venosum

Sono Evaluation of Placenta -Identified as early as ____ weeks -Homogeneous pebble-gray appearance with smooth borders between ___-___ weeks -after ____ weeks-intraplacental sonolucencies and calcifications appear -______- maternal lakes of blood- seen within ______ -Size varies -increased in size and volume with ______ -rarely exceeds __cm in a normal fetus -enlarged placenta are primarily caused by _______, _______ or _______ -Measure with transducer _______ in relation to myometrium -Do not confuse _______ with Braxton Hicks contraction

8, 8-20, 20, lacunae, GA, 4, Rh sensitization, diabetes, or congenital anomalies, perpendicular, placentomegaly

Fetal Placental Uterine Circulation -Oxygenated blood -maternal blood is brought to the placenta through _______ spiral/branch uterine arteries -enters intervillous space near the central part of each lobe where it flows around and over the surface of the ______ -Oxygen rich blood passes through the _______ into the fetal abdomen. Some is distributed to the ______ but most passes through the ________ into the IVC and continues to the heart.

80-100, villi, umbilical vein, liver, ductus venosus

develops at the 28th menstrual day

Amnion

the maternal surface of the placenta

Basal Plate

Maternal Portion of placenta

Basal plate- which lies continguous with decidua basalis

spontaneous painless uterine contractions described originally as a sign of pregnancy; they occur from the first trimester to the end of pregnancy

Braxton-Hicks contraction

Benign vascular tumor of the placenta

Chorioangioma

originate from trophoblastic cells and remains in contact throughout pregnancy

Chorion

the fetal surface of the placenta

Chorionic Plate

Contains intervillous spaces where the maternal blood enters

Chorionic Villi (major functioning unit)

Fetal Portion of placenta

Chorionic plate- which is contiguous with the surrounding chorion (chorion frondosum)

Attachment of the membranes to the fetal surface of the placenta rather than to the underlying villous placental margin

Circumvallate/Circummarginate Placenta

Do not reflect actual function placental units and are probably not meaningful physiologically

Cotyledons

lobes of the placenta (approximately 15-20 lobes)

Cotyledons

Attributed to regulation of intervillous circulation

Fibrin Deposition

Commonly known as molar pregnancy

Gestational Trophoblastic Disease

-Presence of thrombus within the intervillous spaces -results from _______ hemorrhage caused by breaks in the villous capillaries -associated with ________ and elevated _____ levels from a fetal maternal hemorrhage -Sonographic Findings -Sonolucencies (________) -seen within the homogeneous texture of the placenta -Sonolucencies increase with advanced ______ and indicate maturity of the placenta

Intervillous Thrombosis, intraplacental, Rh sensitivity, AFP, anechoic, GA

does not cover the os, but the edge of the placenta touches but does not cross the internal cervical os

Marginal Previa

defined as an abnormal penetration of the placental tissue beyond the endometrial lining of the uterus

Placenta Invasion

Hemorrhage may occur within or around the placenta and is more commonly seen than a placental abruption

Placental Hemorrhage

Premature separation of placenta from uterine wall -bleeding in _______ occurs with separation

Placental abruption, decidua basalis

Clinical Findings of Placental abruption

Preterm labor, vaginal bleeding, abdominal or back pain, fetal distress or demise, uterine irritability

-Accessory lobe -The presence of one or more accessory lobes connected to the body of the placenta by placental vessels

Succenturiate Placenta

-Life threatening -intramembranous vessels can come across internal os -usually caused by velamentous insertion/succenturiate lobe

Vasa Previa

mucoid connective tissue that surrounds the vessels within the umbilical cord

Wharton's jelly

-16 weeks- fusion of amnion and chorion

Yolk sac

Doppler Evaluation of Placenta -Uterine arteries -signals depend on _______ and placental ______ -1st trimester -______ resistive- usually disappears with increasing gestational age and trophoblastic invasion -2nd trimester -typically a ______ resistance waveform -Spiral uterine arteries (normal) -_____ resistive waveform -seen on side of placenta -Abnormal association

^ GA, location high low high Abnormal association placental insufficiency IUGR preeclampsia placental abruption

premature detachment of the placenta from the uterine wall

abruptio placenta

Placenta Invasion -Placental invasion is defined as an abnormal penetration of the placental tissue beyond the endometrial lining of the uterus -Placenta _____ (mild blood loss) -chorionic villi attach superficially into myometrium without muscular invasion -Placenta ______ (moderate blood loss) -further extension of the chorionic villi deep into the myometrium -Placenta ______ (severe blood loss) -penetration of the chorionic villi through the myometrium -most dangerous type

accreta, increta, percreta

the maternal surface of the placenta that lies contiguous with the deciduas basalis

basal plate

Maternal -________- lies near the myometrium -Composed of compressed sheets of _______ -Irregular grooves divide it into ______

basilar plate, decidua basalis, cotyledons

cord insertion into the margin of the placenta within _____mm of the edge or at the periphery

battledore placenta, 10

Placental Hemorrhage -refers to ______ from the placenta from any cause -locations include _______, ______, _____, ______ -A hemorrhage seen in the ______ trimester does not carry the same risk as hemorrhage in the 3rd trimester -1st trimester hemorrhages are more likely to ______ spontaneously if bleeding subsides

bleeding, retroplacental, subchorionic, subamniotic, intraplacental, 1st, resolve

-Normal cord insertion is near the ______ of the placenta

center

-2nd most common placental tumor (but rare) -trophoblastic disease #1

chorioangioma

-large tumors can act as arteriovenous malformations shunting blood from the fetus

chorioangioma

Villi related to decidua basalis increase rapidly in size and complexity to become the

chorion frondosum

the portion of the chorion that develops into the fetal portion of the placenta

chorion frondosum

Villi associated to chorionic sac atrophy and disappear to become the ______ (smooth chorion)

chorion leave

Embryonic/fetal membranes are comprised of

chorion, amnion, yolk sac and allantois

part of the chorionic membrane that covers the placenta

chorionic plate

Fetal -________- echogenic and closest to amniotic cavity -Covered by amniotic membrane -Composed of multiple functional units- ______ -provide for transfer of _______ products -Villi project into pools of maternal blood known as ___________ -Area of cord insertion

chorionic plate, villi, metabolic, intervillous spaces

microscopic vascular projections from the chorion that combine with the maternal uterine tissue to form the placenta

chorionic villi

The Placenta as an Endocrine Gland -__________ -functional endocrine units of the placenta -_________ -inner layer -__________ -outer layer -produces ______ -maintains the ________ in early pregnancy -produces _______ -directs nutrients to the fetus

chorionic villi, cytotrophoblast, syncytiotrophoblast, hCG, corpus luteum, hPL(human placental lactogen)

a placental condition in which the chorionic plate of the placenta is smaller than the basal plate, with a flat interface between the fetal membranes and the placenta

circummarginate placenta

a placental condition in which the chorionic plate of the placenta is smaller than the basal plate; the margin is raised with a rolled edge

circumvallate placenta

the cervical internal os is completely covered by placental tissue

complete or total previa

the part of the decidua that unites with the chorion to form the placenta

decidua basalis

the part of the decidua that surrounds the chorionic sac

decidua capsularis

Fetal Placental Uterine Circulation -Deoxygenated Blood -By the fetal heart via _________- descending ______- internal _____ arteries- _______ arteries-umbilical cord-placenta for respiratory and nutrient exchange -Umbilical arteries in placenta -divide into multiple ________ -The circuit of blood is completed in the fetus through the _____ and back to the heart

ductus arteriosis, aorta, iliac, umbilical, tiny capillaries, liver

connection that is patent during fetal life from the left portal vein to the systemic veins (inferior vena cava)

ductus venosus

Placental Infarcts -focal discrete lesion -caused by _______ -common ____% of pregnancies -usually small with no clinical significance -Sonographic Appearance -_______ acute state -______ may occur over time

ischemic necrosis, 25%, hypoechoic, calcification

fibrous remains of the ductus venosus from fetal circulation

ligamentum venosum

-implanted in the lower uterine segment but its edge does not reach the internal os

low lying placenta

lower part of the uterine cavity, which expands during pregnancy and joins with the cervical canal

lower uterine segment (LUS)

Placenta Position Usually "_______" cephalically from the lower uterine segment in ____ and _____ trimesters -associated with _____ segment growth Pitfalls -_________ (myometrial) contractions -normal contractions of pregnancy -should not be confused with placental pathology -should resolve within _____ mins -Maternal _______ may compress lower uterine anatomy and give false impression of placenta ____ -Have patient ______ which reduces the pressure on the lower uterine segment and allows the cervix to assume a more normal position

migrates, 2nd and 3rd, lower Braxton Hicks, 20 min full bladder, empty bladder

also known as gestational trophoblastic disease; abnormal proliferation of trophoblastic cells in the first trimester

molar pregnancy

The Placenta in Multiple Gestation -Monochorionic.Diamniotic- mo/di -Monochorionic/monochorionic= mo/mo -mo/di or mo/mo from ________pregnancy (one egg) -Dichorionic/diamniotic= di/di -usually _______ pregnancy -Determine -size and # of placenta -type of pregnancy -Risks -monochorionic -______ (placental vascular anastomosis) -Monoamniotic -________

monozygotic, dizygotic, twin to twin, umbilical cord entanglement

only partially covers the internal os

partial previa

growth of the chorionic villi superficially to the myometrium; it does not penetrate through the myometrium

placenta accreta

growth of the chorionic villi deep into the myometrium

placenta increta

growth of the chorionic villi through the myometrium to the uterine serosa

placenta percreta

-Most common cause of painless vaginal bleeding in 2nd and 3rd trimesters -Overdistended bladder may cause placenta to appear low lying

placenta previa

placenta grows in the lower uterine segment and covers all or part of the cervix

placenta previa

-The ________ is dedicated to the survival of the fetus -The placenta will compensate by becoming more efficient in cases of -_________, ________, ________ or _______ -Severe or multiple stresses can lead to _________ -Reduction in uterine blood flow from ________, ________ or ________ -flow may result in IUGR -Placenta membrane is often called a _______

placenta, malnutrition, mother who is diseased, smokes or takes cocaine, placental damage, hypertension, renal disease or placental infarction, barrier

placenta is attached to the uterine wall; as the uterus enlarges, the placenta "moves" with it; therefore, a low-lying placenta may move out of the lower uterine segment in the second trimester

placental migration

Placental Abnormalities Size and Causes -_________ is enlarged placenta weighing more than ____ grams and thickness measuring greater than ____cm

placentomegaly, 600 grams, 4 cm

-Abruptio Placenta may be further classified as ______ or marginal

retroplacental

Fibrin Deposition most common site

subchorionic area( baby side)

one or more accessory lobes connected to the body of the placenta by blood vessels

succenturiate placenta

occurs when the intramembranous vessels course across the internal cervical os

vasa previa

cord insertion at the membranes (pulls away from the placenta)

velamentous placenta

-Transfers the nutrients to the embryo while the uteroplacental circulation is developing -less than ___mm by ____ weeks

yolk sac , 5, 9