OB: EARLY PREGNANCY MULTIFETAL GESTATION Flashcards
The later the twinning the…
The later the twinning event, the worse the outcome and the greater the risks
What is used as ecclampsia prophylaxis in multi-fetal gestation?
multifetal gestation management to include 81 mg of aspirin, started between week 12 and 28, ideally before week 16, for eclampsia spectrum prophylaxis.
Dizygotic twinnning
Two oocytes that are fertilized separately will have nonidentical DNA. This is termed dizygotic (two zygotes) twinning. These are two separate, independent gestations that happen to be going on simultaneously in the same uterus.
Twinnning event
A twinning event is when undifferentiated blastomeres become two distinct organisms, both of which follow the path of differentiation. Only undifferentiated blastomeres can twin.
Blastomere
Normally, a single spermatozoon fertilizes a single oocyte. The combination of those two cells’ haploid nuclei forms the diploid nucleus. At this stage, the organism is a zygote. Cleavage is the process by which one cell becomes two, two become four, four become eight, etc. Each of these cells is called a blastomere and is completely undifferentiated, capable of becoming an entire organism, termed totipotent.
ONLY BlASTOMERES CAN TWIN
chorionicity
chorionicity (how many placentas)
amnionicity
amnionicity (how many amniotic cavities).
If you have monozygotic monochorionic and diamniotic twins, when did the twinning event occur?
After day 3, there will always be one chorion. After day 8, one amnion. After day 13, one embryo.
So between days 3 and 7ish
What are twin pregnancies at risk for?
All twins are at risk for cesarean delivery because they get in each other’s way and present with breech birth, preterm birth, and the eclampsia spectrum.
monozygotic monochorionic and diamniotic twins are at risk for…
twin-twin transfusion
monozygotic monochorionic and monoamniotic twins are at risk for…
cord entanglement
Monozygotic/Dichorionic/Diamniotic twinning event before day…
twinning event before any differentiation, before day 3
Because ALL monochorionic twins are at high risk for twin-twin transfusion syndrome, beginultrasound surveillance at week
16, and repeat/continue every 2 weeks.
The twinning event occurs after the chorion and amnion have differentiated (day 8)
Monozygotic/Monochorionic/Monoamniotic
When will twins be conjoined?
If the twinning event occurs before embryonic differentiation (before day 13), there will be unconjoined twins. If the twinning event occurs after embryonic differentiation (day 13), there will be conjoined twins.
