ERU-31 Multiple Gestations

Question 1

Monozygotic vs dizygotic twins

Answer 1

mono: arising from a single egg/sperm combo that divides
di: 2 eggs, 2 sperm, 2 zygotes

Question 2

For monozygotic twins, at what gestational day would the twins split to create:

• monochorionic, monoamniotic
• monochorionic, diamniotic
• dichorionic, diamniotic

Answer 2

After day 8
Btw day 4-8 (most common)
< day 4

Question 3

how do yolk sacs relate to chorion or amnion?

Answer 3

One yolk sac = 1 amniotic sac

Question 4

What are the sonographic findings of twin-twin transfusion syndrome?

Answer 4

Monochorionic twins
Discordant fetal growth
Oligo donor twin
Poly recipient twin and possible hydropic

Question 5

What are the sonographic findings of Acardiac twinning?

Answer 5

AKA TRAP sequence

• Normal pump twin
• acardiac twin with absent upper body and heart, hydrops

Question 6

What is the most common form of conjoined twin?

Answer 6

Thoracopagus: attached at chest
Omphalopagus: attached at belly

Less common:
Craniopagus: attached at head
Pyopagus: attached at sacrum (back to back)
Ischiopagus: Joined at pelvis

Question 7

fetus papyraceus

Answer 7

When a fetus dies in the first trimester and is maintained throughout the pregnancy

Question 8

Twin embolization syndrome and porencephaly are associated with what event?

Answer 8

Death of a monozygotic twin in the 2nd or 3rd trimester