OB 49 Flashcards
two ways to date a pregnancy
conceptual age, gestational age
gestational age is also known as
menstrual age
conceptual age is also known as
embryologic age
gestational age adds ______ to conceptual age
2 weeks
the conceptus 12 days after conception
zygote
the conceptus from time of implantation to the end of the 10th week of menstrual age
embryo
the conceptus after 10 weeks
fetus
trophoblastic cells become what
the placenta
glycogen-rich mucosa that nourishes early pregnancy
decidua
implantation into uterine decidua is completed within _____ after fertilization
12 days
during implantation, enzymes from the trophoblasts “eat into” decidual tissue to create space for trophoblastic cell proliferation. These are blood pools called ____ ?
lacunae
lacunae and trophoblastic cells develop into mature _____
placental/maternal circulation complex
results in light vaginal bleeding about the same time as expected menstrual period
implantation bleeding
within the conceptus, the inner cell mass matures into the _______
embryonic disc
yolk sac seen sonographically
secondary yolk sac
when does the primary yolk sac pinch off and form the secondary yolk sac?
23 days gestation
phase between weeks 4-10
embryonic phase
initial heartbeat occurs
between 5 1/2 and 6 weekss
during the embryonic phase, the embryo changes from a flat, disk-like configuration to a _______
C-shaped structure
by the end of the 10th week, the crown-rump length(CRL) is what?
35mm
weeks 11 & 12 are the begining of this phase
fetal period
in the fetal period, the fetal head is disproportionately larger than the rest of the fetus by how much
one half of the CRL
fetal anatomy is fully developed when?
late first trimester
When measuring hCG levels: urine results are positive or negative
qualitative
When measure hCG levels: provides specific levels of hCG in blood
quantitative
normal gestational sac is expected to be seen when hCG level is _______
3000 mIU/ml or greater
normal IUP demonstrates ________ of hCG levels every 2-3 days
doubling
hCG levels ______ before spontaneous expulsion of nonviable gestations(spontaneous abortion)
decrease
when do hCG levels plateau and start to decline?
at 9-10 weeks
for downs syndrome detection– hCG levels ____
are increased in the 1st/2nd trimester
for downs sydrome detection PAPP-A levels ______
decreased levels in the 1st trimester
When is the gestational sac sonographically visualized?
5th week
portion on myometrial/burrowing side of conceptus
decidua basalis
villi covering developing embryo
decidua capsularis
interface between decidua basalis and decidua capsularis
double decidual sac sign
gestational sac grows at rate of ______ in early pregnancy
1mm per day
visualization of yolk sac predicts viable pregnancy in over ____
90%
failure to visualize yolk sac when the MSD of the gestational sac is ____ or greater is abnormal
12mm
normal yolk sac diameter should not exceed
6mm
embryo should be seen with a MSD of
greater than 18mm
embryionic heartbeat must be seen when CRL is
greater than 4mm
fusion of membranes(chorioamniotic fusion) occurs at
14-15 weeks. should be complete by 16 weeks
spine develops from the
ectoderm
spine may be visualized as parallel echogenic lines at ____
6 weeks
by 8 weeks, 3 vesicles seen within fetal brain…
prosencephalon, mesencephalon, rhombencephalon
rhombencephalon divides into two parts ….
cephalic and caudal
rhombencephalon–cephalic:
forms cerebellum and pons
rhombencephalon-caudal:
forms medulla
when the rhombencephalon divides, what forms?
cystic rhomboid fossa
cystic rhomboid fossa should not be confused with…
dandy-walker malformation
cystic rhomboid fossa sonagraphically seen….
from 8-10 weeks
hands and feet are completely formed _____
by the end of the 10th week
anterior abdominal wall is developed by______ from four ectomesodermal body folds
6 weeks gestation
midgut loop descends into the fetal abdomen at about the
11th week
the echogenic mass(midgut loop) is no longer visualized outside of the fetus, but rather inside of it after _____ weeks
12 weeks
first organ to function within embryo
heart
when has the heart obtainted its adult configuration
by the end of the 8th week
embryonic heart rates at 6 weeks
90-115
embryonic heart rates at 9 weeks
140-160
MSD formula
(L+W+H)/3
CRL is the most accurate method for dating through
12 weeks
small fluid pocket along fetus’ back during 1st trimester
nuchal translucency
when is NT measured
11-14 weeks (11 weeks 0 days- 13 weeks 6days)
CRL must be ____ for NT measurement
45-84mm
NT measurement…fetal head must be in what position
neutral position
