Ch. 20 Multiple Gestations Flashcards
Multiple gestations that occur from one fertilized ovum (zygote) are referred to as ——. Multiple gestations that occur when two ova are fertilized (two zygotes) are called —–.
Monozygotic, dizygotic
Fraternal twins, occur when two ova are fertilized by two sperm, genders may be same or different
Dizygotic twins
How many chorions, amnions and placentas are found in a dizygotic pregnancy
Two chorions, two amnions, two placentas
Sono finds of dizygotic twins
confirmed by fetuses with different genders
two chorions
two placentas (may be fused)
two amnions
“twin peak sign” aka “lambda sign”
two yolk sacs
Type of twins in which identical fetuses arise from a single fertilized ovum, these twins are always the same gender
Monozygotic twins
What sign is seen on the membrane in a monozygotic pregnancy
“T sign”
Sono finds of a monochorionic diamniotic gestation
2 separate sacs
1 placenta
thin membrane with “T sign”
2 yolk sacs
Sono finds of monochorionic monoamniotic twins
1 sac
1 placenta
1 yolk sac
If the embryonic disk divides after —- days gestation, there will be conjoined twins
after 13 days
If the morula divides during the first four days of gestation, what type of twins will occur?
Dichorionic diamniotic
If the blastocyst splits during the first week of gestation, what type of twins will occur?
Monochorionic diamniotic
If the blastocyst splits during the second week of gestation, what type of twins will occur?
Monochorionic monoamniotic
List clinical findings of multiple gestations
Increased hCG
increased MS-AFP
increased uterine size (“large for dates”
What maternal complications may arise during a twin pregnancy
HTN
Preeclampsia/eclampsia
placental abruption
postpartum hemorrhage
preterm labor and or delivery
anemia
What fetal complications are more likely to occur in a twin pregnancy
Prolapse, entanglement, or compression of an umbilical cord
cord knots in monoamniotic twins
difficult delivery due to abnormal positions
IUGR due to plac insufficiency
hypoxia
increased risk of fetal anomalies
Complication of a twin pregnancy in which there is a demise of a co-twin causing the maternal body to reabsorb the embryo/fetus and sac.
“Vanishing twin”
Twin to twin transfusion syndrome aka Poly-oli sequence occurs in which kind of twins
Monozygotic twins with monochorionic placentation
T or F, TTTS has a high mortality rate for the donor twin only, the recipient twin will be okay
False. TTTS has a high mortality rate for both donor and recipient twin alike
List treatment options for Poly-oli sequence
Amnioreduction
fetoscopic laser photocoagulation of chorionic plate vessels
(laser off the shared vessels)
Sono finds of TTTS in regards to weight and AC
20% difference in fetal weights or AC difference of >20mm
Sono finds of TTTS for the recipient twin
Poly
edema and hydrops
large for dates with enlarged viscera
Sono finds of TTTS for the donor twin
Oligo
small for dates
“STUCK TWIN” phenomenon: donor fetus positioned in severely oligo sac, causing it to be immobile
what does TAPS stand for
Twin-anemia - polycythemia sequence
What is TAPS
A form of TTTS with AV anastomoses at the placental edge which allows slow transfusion of blood from the donor to the recipient. There will be highly discordant hemaglobin concentrations at birth. DONOR IS ANEMIC.
When does TAPS most likely occur
After laser treatment for TTTS
How will amniotic fluid in TAPS be affected and what doppler is the most crucial in diagnosing TAPS
normal amniotic volumes
MCA doppler is crucial in diagnosis
The passage of thromboplastic material or blood clots from a dead monochorionic twin to the remaining live twin through shared intraplacenta vasculature
Twin embolization syndrome
Sono finds of twin embolization syndrome
intrauterine death of the co-fetus
hydrops
poly
enlarged echogenic kidneys
GI or GU deficits
A form of mono mono twinning in which there is an acardiac twin aka holoacardius; “monster”) that has no direct connection with the placenta
Acardiac twinning / parabiotic twin / twin reversed arterial perfusion (TRAP sequence)
Sono finds of the acardiac twin in TRAP sequence
multiple structural anomalies
no cardiac motion
may move and grow
anencephaly or small head
cystic hygroma
Sono finds of the Pump aka donor twin in TRAP sequence
hydrops fetalis
usually sonographically normal except for cardiomegaly due to increased output
may develop heart failure and hydrops due to cardiac burden
Occurs when there is oncomplete division of the embryonic disk after 13 days gestation
Conjoined twins
Conjoined twins at the thorax (most common)
Thoracopagus
Conjoined twins at the liver, possibly intestines, abd wall
omphalopagus
Conjoined twins at the sacrum
pyopagus
Conjoined twins at the ischium/pelvis
Ischiopagus
