Multiple Gestations Flashcards
Twins arising from a single zygote
Monozygotic
Twins arising from two separate zygotes
Dizygotic
A fertilized egg
Zygote
Union of sperm and egg
Fertilization
Twins with separate placentas
Dichorionic
Twins who share the same amniotic sac
Monoamniotic
Most common form of twins
Dizygotic
Disygotic twins always result in ___chorionic and ___amniotic
Dichorionic and Diamniotic
Twins arising from a single zygote that splits
Monozygotic
Splitting of a zygote is termed
Cleavage
Most common form of monozygotic twins
Monochorionic and Diamniotic
When cleavage happens before day 4:
Dichorionic and Diamniotic
When cleavage happens between days 4-8
Monochorionic and Diamniotic
Cleavage happens after day 8:
Monochorionic and monoamniotic
Least common monozygotic twins:
Monochorionic and monoamniotic
Sonographic sign confirming chorionicity in the 2nd/3rd trimesters
Twin peak/lambda/delta sign
What sign is this? What does this prove?
Lambda/twin peak/delta sign. Proving dichorionic
With Twin to Twin Transfusion Syndrome(TTTS) the twin that shunts blood to the other is called:
Donor twin
With TTTS, which twin is smaller?
Donor
With TTTS, twin that receives shunted blood:
Recipient
Severe oligohydramnios surrounding a twin that appears to be closely associated with the uterine wall
Stuck twin
Severe form of TTTS
Acardiac twinning
Acardiac twinning aka
Twin-Reversed Arterial Perfusion
Abnormal anastomoses of placental vessels in a twin pregnancy
- one normal twin
- one twin is missing the upper body and heart
Acardiac twin
The most common forms of conjoined twins:
- thoracopagus—chest
- omphalopagus—stomach
Conjoined twins joined at the cranium
Craniopagus
Conjoined twins joined at the back
Pyopagus
Conjoined twins joined at the pelvis
Ischiopagus
The death of a twin and subsequent reabsorption during the fist trimester
vanishing twin
Twin dies in first trimester but is not reabsorbed and is maintained throughout the pregnancy
Fetus papyraceus
- Death of a monochorionic twin
- vascular products travel from demised twin to the surviving twin
- CNS, kidneys damaged
- hydrocephalus and porencephaly
Twin embolization syndrome
During first trimester, DICHORIONIC twins will be separated by:
Thick membrane separating the two amniotic sacs
Thick membrane—proves dichorionic
Arrowheads are pointing to what in this 1st trimester scan?
No thick membrane—Monochorionic
Arrowheads—Separate amnion for each fetus—Diamniotic
Median gestational age of delivery for twins
35 weeks
Twins at risk for being conjoined:
Monochorionic Monoamniotic
