Normal First Trimester Flashcards
cavity in which the fetus exists; it forms early in gestation and fills with amniotic fluid to protect the fetus
amniotic cavity
surrounds the amniotic cavity; the yolk sac is within the chorionic cavity
chorionic cavity
invasive diagnostic genetic testing that involves sampling zygotic cells from developing placental tissue
chorionic villi sampling (CVS)
most accurate measurement of the embryo in the first trimester
crown-rump length (CRL)
the uterine decidual surface on the maternal side of the placenta; the decidual basalis is invaded by trophoblastic cells that form the placenta
decidua basalis
the uterine decidua on the surface of the implantation site. As the pregnancy progresses, the decidua capsularis may shed, causing light early pregnancy bleeding
decidua capsularis
multiple pregnancy with two amniotic sacs
diamniotic
multiple pregnancy with two chorionic sacs
dichorionic
interface between the decidua capsularis and the echogenic, highly vascular surface on the opposite side of the endometrial cavity
double decidual sac sign
age calculated from when conception occurs
embryologic age (conceptual age)
time between 4 and 10 weeks’ gestation
embryonic period
production and development of blood cells
hematopoiesis
hormone secreted by the trophoblastic cells (developing placental cells) of the blastocyst; laboratory test indicates pregnancy when values are elevated
human chorionic gonadotropin (hCG)
intrauterine pregnancy
IUP
length of time calculated from the first day of the last normal menstrual period (LMP) to the point at which the pregnancy is being assessed
menstrual age (gestational age)
multiple pregnancy with one amniotic sac
monoamniotic
multiple pregnancy with one chorionic sac
monochorionic
mean sac diameter
MSD
first site of formation of red blood cells that will nourish the embryo
primary yolk sac
formed at 23 days when the primary yolk sac is pinched off by the extraembryonic coelom
secondary yolk sac
high-frequency transducer that is inserted into the vaginal canal to obtain images of first-trimester pregnancy
transvaginal (TV) transducer
the umbilical duct connecting the yolk sac with the embryo
yolk stalk
the conceptus resulting from the union of male and female gametes. In a normal pregnancy, the zygote travels through the tubes and implants in the uterus
zygote
Which area of the embryo attaches to the amnion?
umbilical insertion
Gestational weeks 6 through 10 constitute the:
embryonic phase
Which of the following formulas calculates the mean sac diameter of the gestational sac?
(length + height + width)/3
The chorionic cavity should no longer be visible after how many gestational weeks?
16
The mean sac diameter measures gestational age before visualization of the:
embryo
Which is the most accurate method for measuring gestational age?
crown rump length (CRL)
Normal human chorionic gonadotropin levels should _____ every _____
double every 30 to 48 hours
When measuring the mean sac diameter, the calipers should be placed from the ____ wall to _____ wall
inner wall to inner wall
What lines the chorion and contains the fetus?
amnion
The term embryo is used to describe a developing zygote through the ____th gestational week
10th
-organogenesis is generally completed by the 10th gestational week
TRUE
What is the membrane called that surrounds the fetus or embryo?
amnion
What is the name of endometrial layer that is on the maternal side?
decidua basalis
The placenta develops from the _____________?
chorion
True or False: The FHR should be 140 +/- 20 BPM by 9 weeks.
TRUE
What produces amniotic fluid in the 1st trimester?
amnion
What is the cystic structure that is noted in the fetal head?
Rhombencephalon
When should the amnion and chorion be fused?
14 weeks
12 days after conception, during the implantation process
zygote
From the time of implantation until the end of the 10th week menstrual age
embryo
After the first 10 weeks
fetus
conception as first day of pregnancy
conceptual age or embryologic age
First day of last menstrual period as the beginning of gestation
gestational or menstrual age
Fertilization occurs withing ______ days after ovulation.
1 to 2 days
At approximately _____ days menstrual age, the primary yolk sac is pinched off by the extraembryonic coelom, forming the secondary yolk sac. The amniotic chorionic cavities also develop and evolve during this period of gestation.
23
The embryonic phase occurs from week ______. During this phase all major internal and external structures begin to develop.
4 through week 10
The cardiovascular system undergoes rapid development, with the initial heartbeat occurring at between _______ weeks or ____ days.
5.5 to 6 weeks or 35 days
The crown-rump length measures _____ by the end of the 10th week.
35mm
The gestational sac is approximately ____ mean sac diameter at ten weeks.
45mm
hCG should double every _____ days
2-3 days
Gestational sac and hCG peaks at _____ weeks
8-10
1st trimester hCG is secreated by the _________ cells of the ________.
trophoblast, blastocyst
Transvaginal transducers are _____ MHz
5 to 8
Intrauterine pregnancy usually measures ___ at _____ weeks.
1cm, 5.5 weeks
normal sac grows ____ per day in first trimester
1mm
Gestational sac has a decidual wall thickness greater than ____.
3mm
Endovaginal at _____ weeks gestation and transabdominal at ___ weeks.
4.5, 5
failure to visualize the yolk sac, with a minimum of _____ MSD, using transvaginal sonography, should provoke suspicions of abnormal pregnancy.
12mm
The normal diameter of the yolk sac should not exceed ____.
6mm
The early embryo is often not identified until hear motion is detected at approximately ______, when the CRL is _____.
5.5, 2-3mm
The anechoic center of 5-6 week gestational sac represents the _______.
chorionic cavity
by week ____, three primary vesicles are seen within the feta brain: the prosencephalon, mesencephalon, and rhombencephalon.
8
The mid-gut herniation occurs and is normally seen between _____ weeks. Normally returns into the abdomen by ___ weeks.
8-12, 12
The embryonic heart starts beating at approximately ___ days (______ weeks). By the end of the ____ week of gestation, the has has reached its adult configuration.
35days, 5 to 5.5 weeks, 8th
Rates of ____ to ____ beats per minute at 6 weeks increases to rates of ____ to ____ beats at 9 weeks, with rates of approxmatly ____ beats the remainder of the the late first and second trimester.
90-115, 140-160, 140
As a rule, the gestational sac size remains accurate through the first ____ weeks of gestation.
8
Crown-Rump length is most accurate dating parameters for gestation dating. Deviations of plus or minus _____ days.
5 to 7
CRL measurements can be obtained as early as ____ weeks using transvaginal scanning. visualization of heart motion is a marker signifying the beginning of CRL measurements.
5.5
CRLs are considered the most accurate method for dating through ______ gestation.
12 week
