16. Multiple Gestations Flashcards
monozygotic twins vs dizygotic twins: The difference
monozygotic twins (identical) or dizygotic twins (not-identical)
The dizygotics are always dichorionic and diamniotic
When the pacenta of the monozygotics split
before 8 days =
after 8 days =
before 8 days = diamntiotic
after 8 days = monoamntiotic
The late splitting of the placent (> 13 days) cause
conjoined twin
Monochorionic
Monoamntiotic
Monochorionic
Diamniotic
Dichorionic
Diamniotic
Fused Placenta
Dichorionic
Diamniotic
Separate placentas
dichorionic diamniotic
“Twin-Peak Sign”
A beak-like tongue between the two membranes
This excludes a monochorionic pregnancy.
Monochorioinic Pregnancy
“T-sign”
the absence of the twin peak sign
You don’t see chorion between membrane layers.
what makes Monochorionic Twins bad for growth?
Monochorionic Twins share a placenta. This placenta (if it has abnormal vascular connections) can allow for blood to be transferred from one fetus to the other - this is bad
This occurs in monochorionic twins when a vascular communication exists in the placenta.
Twin- Twin Transfusion Syndrome (TTTS)
You end up with one greedy fat twin who takes all the
blood and nutrients, and one skinny wimpy looking kid who gets the scraps.
“stuck to the wall of the uterus,” or “shrink wrapped.”
Twin Oligohydramnios Polyhydramnios Sequence (TOPS)
Oligohydramnios for the donor
Polyhydramnios for the recipient
The donor (skinny) twin will also have a high resistance umbilical artery.
Twin Reversed Arterial Perfusion Syndrome (TRAP)
In this more extreme situation the greedy twin is so greedy that he/she doesn’t even bother to develop a heart. Instead, it just uses the heart of the “pump twin.”
This is a severe variant of TTTS.
They usually have wrecked / totally deformed upper bodies - so they probably wouldn’t make it very far in politics and would have trouble rolling the dice in monopoly (since they don’t have arms) … plus they all die in utero.
What are the chronic feto-fetal transtusions?
This is another syndrome related to feto- fetal transfusion but this time
“there is no difference in amniotic fluid.”
Instead you essentially have a transfer of hemoglobin (Hgb) with one anemic twin and one twin with polycythemia.
Twin Anemia Polycythemia Sequence (TAPS)
