Normal First Trimester
To calculate MSD:
MSD = (L + W + H)/3 MSD + 30 = menstrual age (days)
The optimal gestational age for measuring fetal nuchal translucency is from: a. 11w0d - 13w6d b. 10w0d - 12w0d c. 11w6d - 13w0d d. 11w0d - 12w6d e. 10w0d - 12w6d
a. 11w0d - 13w6d
All of the following are produced by the placenta except: a. AFP b. hCG c. pregnancy-associated plasma protein A d. Inhibin A
a. AFP
Which of the following lines the chorion and contains the fetus? a. amnion b. yolk sac c. decidua basalis d. chorion frondosum e. trophoblastic tissue
a. amnion
What is the stage of the conceptus that implants within the decidualized endometrium? a. blastocyst b. morula c. zygote d. ovum
a. blastocyst
In the first trimester, normal hCG levels will: a. double every 48 hours b. triple every 24 hours c. double every 24 hours d. double every 12 hours
a. double every 48 hours
What is the name of the dominant follicle prior to ovulation? a. graafian b. corpus luteum c. morula d. corpus albicans
a. graafian
embryologic age (conceptual age)
age calculated from when conception begins
The MSD measures gestational age prior to visualization of the: a. amnion b. embryo c. yolk sac d. placenta e. fetal heart
b. embryo
The secondary yolk sac is: a. has no specific function b. is located in the chorionic cavity c. is visualized after the embryonic disk d. represents the developing chorionic villi e. secretes hCG
b. is located in the chorionic cavity
Compared with a normal IUP, the ectopic pregnancy will have: a. high hcG b. low hCG c. markedly elevated hCG d. high AFP
b. low hCG
What hormone, produced by the corpus luteum, maintains the thickened endometrium? a. estrogen b. progesterone c. hCG d. LH
b. progesterone
Initial visualization of the choriod plexus is expected near the: a. 6th gestational week b. 8th gestational week c. 10th gestational week d. 14th gestational week e. 18th gestational week
c. 10th gestational week
On transvaginal imaging, in an IUP, cardiac activity must be identified within a gestational sac with a MSD of: a. 7 mm b. 10 mm c. 16 mm d. 20 mm e. 25 mm
c. 16 mm
Fertilization typically occurs within ________ after ovulation? a. 40 hours b. 12 hours c. 24 hours d. 56 hours
c. 24 hours
Which of the following is the most accurate method of measuring gestational age? a. yolk sac diameter b. MSD c. CRL d. BPD e. nuchal translucency
c. CRL
The first sonographically identifiable sign of pregnancy is the: a. amnion b. yolk sac c. decidual reaction d. chorionic cavity
c. decidual reaction
During a first trimester ultrasound exam, you notice a cystic structure within the head. This most likely represents: a. prosencephalon b. mesencephalon c. rhombencephalon d. proencephalon
c. rhombencephalon
What structure lies within the extraembryonic coelum? a. gestational sac b. embryo c. yolk sac d. amnion
c. yolk sac
amniotic cavity
cavity in which the fetus exists, filled with amniotic fluid
The normal gestational sac will grow: a. 2 mm per day b. 3 mm per day c. 1 cm per day d. 1 mm per day
d. 1 mm per day
The most common site of fertilization is within the: a. isthmus of the uterine tube b. uterine fundus c. cornu of the uterine tube d. ampulla of the uterine tube
d. ampulla of the uterine tube
Another name for the chorionic sac is the: a. chorionic cavity b. extraembryonic coelom c. amniotic sac d. gestational sac
d. gestational sac
The first definitive sonographic sign of an IUP is the recognition of a/an: a. yolk sac b. embryo c. decidual reaction d. gestational sac
d. gestational sac
The trophoblastic cells produce: a. estrogen b. progesterone c. FSH d. hCG
d. hCG
Chorionic villi are more proliferic: a. near the amnion b. adjacent to the yolk sac c. opposite the cervical os d. near the implantation site e. adjacent to the uterine fundus
d. near the implantation site
Which area of the embryo attaches to the amnion? a. calvaria b. nuchal fold c. thoracic cavity d. umbilical insertion e. none of the above
d. umbilical insertion
zygote
fertilized ovum resulting from the union of male and female gametes
primary yolk sac
first site of formation of RBCs that will nourish the embryo
When should an embryo be visualized?
gestational sac is > 18 mm
cytotrophoblast/embryoblast
inner cell mass that develops into embryo, amnion, umbilical cord and yolk sac
endoderm
inner layer that forms the lungs, intestines, and urinary bladder
double decidual sac sign
interface between the decidua capsularis and the echogenic, highly vascular endometrium
mesoderm
middle layer that forms the heart, circulatory system, bones, muscles, kidneys, and reproductive system
syncytiotrophoblast
outer layer of trophoblast that creates chorionic membranes and actively invades the uterine endometrium to form the outermost fetal component of placenta
ectoderm
outer layer that forms the brain, spinal cord, spine, and spinal nerves
hematopoiesis
production and development of blood cells
In the first 8 weeks, how does the gestational sac size and hCG levels increase?
proportionately
chorionic cavity
surrounds the amniotic cavity, contains the yolk sac
embryonic period
time between 6 and 10 weeks of gestation
yolk stalk
umbilical duct connecting the yolk sac with the embryo
decidua capsularis
villi surrounding the chorionic sac
secondary yolk sac
-formed at 23 days when the primary yolk sac is pinched off by the extra embryonic coelom -yolk sac seen sonographically
When should a yolk sac be visualized?
-gestational sac is > 10 mm -transabdominally 6-7 weeks -transvaginally 3-4 weeks
What happens to hCG levels after 8 weeks? Gestational sac?
-hCG levels plateau and decline -gestational sac continues to grow
hCG (human chorionic gonadotropin)
-hormone secreted by the trophoblastic cells of the blastocyst -doubles every 48-72 hours
menstrual/gestational age
-length of time calculated from the first day of the last normal menstrual period to the point at which the pregnancy is being assessed -add 2 weeks to conceptual age
What are the functions of the amniotic fluid?
-permits symmetric growth of fetus -prevents adhesions from forming in the fetal membranes -cushions the fetus and acts as a shock absorber -maintain proper temperature -allows normal development of the respiratory, gastrointestinal, and musculoskeletal systems -prevent infection -source of nutrients
chorion frondosum
-portion of chorion at implantation site that invades the decidua basalis
What are the 3 primary brain vesicles that develop around the 6th week of gestation?
-prosencephalon (forebrain) -mesencephalon (midgrain) -rhombencephalon (hindbrain)
What are the essential functions of the secondary yolk sac?
-provision of nutrients -hematopoiesis -development of embryonic endoderm
What are the sonographic features of a normal gestational sac?
-round or oval shape -located in fundal or middle portion of uterus, center relative to endometrium -smooth contour -decidual wall thickness > 3mm
corpus luteum cyst
-small yellow endocrine structure that develops within a ruptured ovarian follicle and secretes progesterone and estrogen -regresses 16-18 weeks
allantois
-tubular diverticulum of the posterior part of the yolk sac that collects liquid waste from the embryo and removes waste (gas)
decidua basalis
-villi on maternal side of the placenta or embryo -unites with the chorion to form the placenta
When does bowel herniation return to the fetal abdomen?
11-12 weeks
When is the yolk sac no longer visualized?
12th week
When does chorioamniotic fusion occur?
16-17 weeks
At what hCG levels should a gestational sac be visualized?
1800 mIU/ml range 1000-2000 mIU/ml
Heart activity should be seen when the embryo is what size?
4 mm
When does the blastocyst typically enter the uterus?
4-5 days after fertilization
When is the embryonic heart rate first heard?
5-5.5 weeks
When does the embryo transition from a two later embryonic disk to a trilaminar disk?
5th week
When are the limb buds recognizable?
6th week
When does the trilaminar embryonic disk fold into a C-shaped emberyo?
6th week
When does implantation occur?
7-9 days after fertilization