Lecture 4A - Normal First Trimester (Early) Flashcards
what do you assess for a dating scan? (3)
gestational sac (presence, #, size, GA) embryo (size + cardiac activity) maternal structures
dating scan occurs during what week range
0-13 weeks
patient history questions (6)
Full bladder LMP positive pregnancy medication irregular bleeding
embryonic structures that slowly become visible (4)
JAMAL
when does implantation occur
day 20-23
what is the first (non-diagnostic) sign
focal echogenic thickening on one side of endo
when youre looking at the gestational sac, what are you looking at?
chorionic cavity
when is the GS visible
4.5-5 weeks
what is IDSS
intradecidual sac sign - GS seen WITHIN decidua
IDSS should be differentiated from (2)
pseudogestational sac
decidual cysts
what confirms intrauterine pregnancy
double decidual sac sign
what is the DDSS comprised of?
double concentric rings around GS (parietalis outer, capsularis inner)
what does mean sac diameter calculate? what is the formula? how do you measure?
gestational age
MSD = (LWH)/3
INNER TO INNER
yolk sac functions (4)
- nutrients
- protein production
- hematopoiesis
- vitelline ducts (connects yolk sac to embryo)
what does the balloon on string represent
yolk sac + vitelline ducts
what is the most accurate measure of GA?
crown rump length, main measurement in 1st trimester
what is the first organ to function?
heart
what mode to assess fetal heart rate
M mode
amnion fuses with walls of
gestational sac (chorion)
double bleb sign includes (3)
YS
Embryo
Amniotic sac
where does the amniotic fluid come from? in 1st and 2nd trimester
1st trimester placenta
2nd trimester urine
what are the important 1st trimester (early) measurements you must take (4)
- MSD
- yolk sac
- fetal pole (CRL)
- fetal HR
what should the yolk sac measurement be under in early first trimester
<5.6 mm
when is the first trimester scan
11-14 weeks
