the first trimester

Visualization of the Early Gestation Round, oval Fundus/mid-uterus, eccentrically placed ________ ____ _____ Grows approx 1mm/day

double sac sign

Normal pregnancy less than 7 weeks demonstrates ___________ of quantitative maternal serum hCG levels every 3.5 days, or increase of 66% in hCG levels within 48 hours

doubling

hCG does not have sufficient sensitivity to be used by itself for screening for ________ _________ (Is combined with other independent markers to increase detection) -(Maternal serum markers = hCG, estriol, AFP, and sometimes inhibin-A)

down syndrome

Chorion/amnion Chorionic cavity is initial _________ ______ for embryonic waste. Later placenta takes over process of waste removal; amniotic cavity expands and chorionic cavity decreases in size Fusion of membranes, chorioamniotic fusion, occurs at approximately 14 to 15 weeks.

dumping ground

Gestational Sac Size -Mean gestational sac size correlates closely with menstrual age during _______ ____________ -Size remains accurate through first ___ weeks of gestation -Measurements obtained in both sagittal and coronal/semicoronal sonographic planes

early pregnancy 8

Interface between decidua capsularis and ___________, highly vascularized decidua on opposite wall of endometrial cavity forms double decidual sac sign, reported to be reliable sign of early IUP

echogenic

Sagittal sonogram of an approximate 6-week gestational sac demonstrating caliper placement for appropriate mean sac diameter measurement. Coronal images would also be taken for a third dimension. -When measuring mean sac diameter, measure only gestational sac fluid space; do not include ___________ _________

echogenic decidua

Sonographer must be aware when hCG value is this level, and if gestational sac not seen within uterus, _________ pregnancy may be considered

ectopic

Between 5½ and 6 weeks of gestation, amniotic cavity and membrane, chorionic cavity, yolk sac, and ________ should be seen.

embryo

Blood tests (hCG levels) should be positive at 7 to 10 days ___________ ____ (conception age) Placenta seen as thickened density (trophoblastic reaction) along part of margin of gestational sac

embryonic age

3. Fetal number should be documented. Count only _________ and _____ ____ to determine multiple pregnancies. Membrane structure and number of amniotic and chorionic membranes should be documented in all multiple pregnancies. Chorionicity most reliably documented during first trimester

embyro yolk sac

Those chorionic villi in contact with the decidua basalis rapidly proliferate to become the chorion frondosum, the ______ part of the placenta.

fetal

Implantation - end of 10th week menstrual age, conceptus called an embryo After first 10 weeks, embryo called a _______

fetus

Growth rate of yolk sac has been reported to be approximately: 0.1 mm/ml of growth of MSD when MSD <15 mm and 0.03 mm/ml of growth of MSD through ______ trimester

first

Secondary yolk sac is yolk sac seen sonographically throughout ______ trimester Often first intragestational sac anatomy seen is sonographic yolk sac (secondary yolk sac) Routinely visualized between 5 and 5½ weeks of gestation

first

Within conceptus, inner cell mass matures into bilaminar embryonic disc, ______ ________, and primary yolk sac Amniotic and chorionic cavities also develop and evolve during this period of gestation.

future embyro

During 28-day menstrual cycle, Mature ovum typically released on day 14 __________- male/female reproductive cell

gamete

Clinicians and Sonographers use ____________ _____ Or, menstrual age, to date pregnancy First day of last menstrual period is beginning of gestation

gestational age

At end of the 3rd week LMP, the chorion differentiates. The chorion which will become the fetal contribution to the placenta proliferates (leafy chorion or chorion frondosum). The remainder of chorion is stretched (bald chorion or chorion laeve) and surrounds the _____________ _____

gestational sac

When implantation complete, trophoblast has formed primary villi (by 5 wks LMP), which initially encircle early ____________ ______

gestational sac

Two parameters for sonographic gestational dating: 1. 2.

gestational sac size crown-rump length

Incorrect Dates, Gestational Trophoblastic Disease, and Multiple Gestation are associated with what type of levels?

greater than

Blastocyst - organized collection of cells The outer lining consists of trophoblasts which produce _____ (Glycoprotein produced by trophoblastic cells and later by the placenta) to extend the life of the corpus luteum (the corpus luteum produces progesterone, which assures the retention of the endometrial lining) implants into endometrium 4-5 days after fertilization Outer lining consists of trophoblasts Trophoblasts - hCG - corpus luteum (progesterone) - retention of lining

hCG

The CRL is the most accurate method of dating a pregnancy sonographically, and is accurate within 3 - 5 days if measured properly. The correct measurement is from the top of the _____ to the bottom of the _______, excluding legs. The embryo grows at a rate of 1mm per day CRL(mm) + 42 = Gestational Age (days)

head rump

The yolk sac is the first structure seen within the gestational sac. Yolk sac seen before beating embryonic ________, because embryonic heart motion begins at approximately 5½ weeks Yolk sac may be used as landmark to image embryo, given connection between yolk sac and embryo

heart

As pregnancy progresses, amniotic cavity grows Corresponding space between embryo and yolk sac __________ Between fifth and sixth weeks' gestation, identification of amniotic membrane may not be possible using transabdominal techniques. Using transvaginal transducers, amniotic membrane that separates amniotic and chorionic cavities routinely seen after 5½ weeks

increases

In pregnancies where fetus is trisomy 21: hCG levels plateau ________ and fall much more ________ Levels of hCG ___________ in these pregnancies as compared to normal pregnancies; difference increases as gestation advances

later slowly increased

Incorrect Dates, Fetal Demise, Ectopic are associated with what type of levels?

less than

Allantois -function is to collect _______ _____ from the embryo and exchange gases used by the embryo

liquid waste

If normal rate of increase not seen, greater chance that pregnancy is ectopic Ectopic pregnancies demonstrate ________ hCG level than IUP perhaps due to limited absorption outside uterus

lower

2. Presence or absence of cardiac activity should be reported. Only use ________!!! No Doppler! Cardiac motion usually seen when embryo 5 mm or greater in length. Fetal heart rate much faster than mother's heart rate

m-mode

Increased hCG levels can be used as screening ___________ for Down syndrome during first and second trimesters

marker

Major Components of Routine- First Trimester Examination Uterus and adnexa evaluated for presence of gestational sac Sonographic _____________ of embryo and/or sac recorded Presence or absence of cardiac activity documented Fetal number documented and chorionicity assessed in multiple pregnancies Uterus, adnexal structures, cul-de-sac evaluated

measurments

________ - mass of dividing cells (16); located in isthmus of oviduct and enters uterus

morula

Abnormal pregnancies demonstrate low hCG level relative to gestational sac development. hCG levels fall before spontaneous expulsion of ___________ gestations Particularly important if there is vaginal bleeding, pelvic pain, or suspicion of ectopic pregnancy Correlate hCG and sono findings

nonviable

First Trimester Sample Protocol 1. Uterus and adnexa should be evaluated for presence of gestational sac. If gestational sac seen, location (intrauterine or extrauterine) should be noted. Gestational sac should be recorded when embryo ____ identified during zygote or implantation stage of pregnancy. Caution must be used in diagnosing gestational sac without presence of yolk sac or embryo since intrauterine fluid collections may appear similar.

not

Functions of secondary, or sonographic, yolk sac in embryonic development: (1) Provide __________ to developing embryo (2) _______________ (3) Development of embryonic endoderm, which forms ___________ _____ -Hematopoiesis-formation of blood cellular components -3 Germ cell layers that comprise the embryonic disk by 5 weeks after LMP -endoderm-inner, mesoderm-middle, ectoderm-outer

nutrients hematopoiesis primitive gut

Fertilization occurs 24-36 hours after ____________ in the ampulla For 12 days after conception, during the implantation process, the conceptus is called a zygote. Single celled fertilized ovum prior to mitotic division

ovulation

Abnormal levels of maternal serum hCG can indicate a problem with the developing ___________

pregnancy

__________ _____ _____ is a microscopic structure and not seen on ultrasound At approximately 23 days menstrual age, primary yolk sac pinched off by extra embryonic coelom, forming secondary yolk sac -Extra embryonic coelom is also called the chorionic cavity.

primary yolk sac

what are some of the things the embryologist does? -conception is the first day of pregnancy

state time in conceptual age or embryologic age

Qualitative-_______ results are positive or negative Quantitative-results provide specific levels of hCG in ________

urine blood

4. Evaluation of __________, __________, and ___________ should be performed. Important to document texture of ovaries and presence of corpus luteum or other adnexal masses; look for inhomogeneous uterine texture that may represent leiomyomatous growth stimulated by hormonal changes of pregnancy

uterus, adnexa, and cul-de-sac

Presence or __________ of yolk sac and embryo should be noted. Crown-rump length most accurate measurement of gestational age during first trimester Should be recorded when embryo present

absence

Decidualized Endometrium 3 layers Decidua __________ Decidua ____________ Decidua ___________/decidua vera

basalis capsularis parietalis

____________ - inner fluid cavity contains the inner cell mass that will become: primitive yolk sac embryo amnion

blastocele

Trophoblasts-cells forming around the ____________ that provide nutrients and oxygen to embryo Trophoblastic cells begin to secrete hCG absorbed within tubes and stimulates maternal pregnancy responses

blastocyst

_____________ begins to implant in decidualized endo by end of the 3rd week LMP Trophoblastic tissue invades (proteolytic enzymes) May cause vaginal bleeding -During implantation, proteolytic enzymes, produced by the trophoblasts "eat into" decidual tissue, creating spaces for trophoblastic cell proliferation.

blastocyst

Decidua basalis-develops where the ___________ implants; maternal contribution to placenta Decidua capsularis-closes over and surrounds the blastocyst, ______ covering developing embryo referred to as decidua capsularis Decidua parietalis-results from ___________ influence on the uninvolved endometrial tissue

blastocyst villi hormonal

___________ - Dividing fertilized ovum at 2-cell and 4-cell stages; Located within ampulla of f. tube

blastomere

trophoblast > chorionic villi + contact with decidua basalis = chorion frondosum Remainder _________ is stretched and surrounds gestational sac

chorion

**Human Chorionic Gonadotropin Glycoprotein produced by trophoblastic cells and later by the placenta Supports _________ __________ Detectable in maternal serum and urine. Forms basis of current pregnancy tests

corpus luteum

Implantation hCG --> endometrium --> Decidua = pregnant endo Glycogen rich Nourishes early pregnancy -hCG causes uterine endometrium to convert to _________, glycogen-rich mucosa that nourishes early pregnancy

decidua

The placenta contains both maternal and fetal tissue. The maternal component is derived from the __________ basalis and the fetal component is derived from the ______________ tissue. By 5 weeks LMP, the trophoblast develops into chorionic villi. Those chorionic villi in contact with the decidual basalis rapidly proliferate to become the chorion frondosum, the fetal part of the placenta.

decidua trophoblastic

Many laboratories use hCG levels of ________ to _________ mIU/mL as number that indicates pregnancy should be visible with sonography

1000 2000

Typically, yolk sac resorbs and no longer seen sonographically by ____ weeks Persistent yolk sac does occur and may be visualized at placental __________ _____ insertion where amniotic and chorionic membranes fused

12 umbilical cord

Amnion forms from inner cell mass Amniotic cavity expands Fusion by 12 - 16 weeks Amniotic cavity expands to fill chorionic cavity The amnion and chorion begin to fuse by middle of the first trimester, with completion by _____ - _____ weeks

12 16

Maternal Serum Biochemistry in Early Pregnancy Normal gestational sac can be consistently demonstrated when hCG level _______ mIU/ml (Second International Standard) or greater when using transabdominal sonography Detection threshold significantly reduced by transvaginal sonography; may be as low as _______ mIU/ml Urine test may be as low as 25 - 50mIU

1800 500

Crown-Rump Length First reported in _______ Produced gestational dating standard deviations of ±5 to 7 days, by far the most accurate dating parameters within obstetric biometry (through 12 weeks)

1975

With an IUP, hCG is detectable in bloodstream 7-10 days after ovulation Doubles every ______ days Plateaus around 8-9 weeks, then declines

2-3

Embyro Early embryo often not identified until heart motion detected at approximately 5½ weeks when CRL approximately ____ mm Embryonic heartbeat must be seen in living embryo when CRL >4 mm

3

Normal Pregnancy Progression Embryonic phase: ____ - _____ weeks During this phase, all major internal and external structures begin to develop. Cardiovascular system undergoes rapid development, with initial heartbeat occurring between 5½ and 6 weeks

4 10

Normal Pregnancy Progression Cell division (cleavage) begins Each cell contains ____ chromosomes

46

During ____ week of embryonic development, intrauterine pregnancy (IUP) can be visualized sonographically. Appears as 1- to 2-mm sac with echogenic ring having sonolucent center ____________ center represents chorionic cavity.

5th anechoic

Normal diameter should not exceed ____ mm Enlarged yolk sacs may have ominous outcomes

6

With Transvag US, the secondary yolk sac is visible at 5 weeks LMP, and is almost always seen when the MSD reaches ___mm. With Transabd US, the yolk sac should be seen 7 weeks LMP, when the MSD is ____mm

8 20

B, The same fluid differences are seen at approximately ____ weeks' gestation.

9

Fetal HR changes according to fetal development stages; early in embryologic development HR slow (_____ bpm) Rate may go up to 180 bpm in middle of first trimester, before returning to 120 to 160 bpm throughout remainder of pregnancy

90

Visualization of yolk sac predicts viable pregnancy in >_____% of cases. Failure to visualize yolk sac, with minimum of _____-mm MSD, using transvaginal sonography, is suspicious for abnormal pregnancy. Transabdominal studies have shown that yolk sac should be seen within mean sac diameters of 10 to 15 mm and should always be visualized with mean sac diameter of 20 mm.

90 12

At this stage, embryo seen between secondary yolk sac and immediate gestational sac wall Because amniotic cavity still relatively small, appears that no space lies between yolk sac and embryo

A 6.2-week gestation at beginning of "curling."

Use this formula to calculate mean sac diameter (MSD): Length (mm) + Width (mm) + Height (mm)/3 = MSD MSD (mm) + 30 = Menstrual age (days) Menstrual age (days) divided by 7 = Menstrual age (weeks) Ex. Length: 17mm; Width: 8mm; Height: 11mm

Ex. 17 + 8 + 11 = 36/3 = 12 12 + 30 = 42 42/7 = 6 weeks

Placentation Maternal (__________ _________) and fetal tissue ( _____________ tissue)

decidua basalis trophoblasic

Yolk sac initially attached to embryo via yolk stalk. At approximately 8 weeks' gestation, with amniotic cavity expansion, the _____ ____, which lies between amniotic and chorionic membranes, detaches from yolk stalk.

yolk sac

Primitive blood exchange network between mother and conceptus formed in the placenta Lacunae and trophoblastic cells develop into mature placental/maternal circulation complex that will sustain pregnancy. At end of implantation process, _________ has buried itself within one wall of uterus

zygote