PU Multiple Gestation Ultrasound 2

Question 1

What defines Quintero Stage II in twin-to-twin transfusion syndrome (TTTS)?

Accepted Answer

Oligohydramnios-polyhydramnios sequence with an absent donor bladder

Answer

Absent or reversed end-diastolic flow in the umbilical artery

Answer

Hydrops in the recipient twin

Answer

Fetal demise of one or both twins

Question 2

Selective intrauterine growth restriction (sIUGR) in monochorionic twins is primarily defined by which finding?

Accepted Answer

EFW of one twin below the 10th percentile for gestational age

Answer

EFW discordance >20% with normal umbilical artery Dopplers

Answer

EFW discordance >10% with abnormal Dopplers in the smaller twin

Answer

Polyhydramnios developing in the larger twin's sac

Question 3

Twin anemia-polycythemia sequence (TAPS) is best identified on ultrasound by which Doppler finding?

Accepted Answer

Middle cerebral artery peak systolic velocity (MCA-PSV) >1.5 MoM in the anemic twin

Answer

Absent end-diastolic flow in the donor twin's umbilical artery

Answer

Reversed a-wave in the ductus venosus of the polycythemic twin

Answer

Elevated umbilical vein pulsatility index

Question 4

In a naturally conceived triplet pregnancy, what is the most common chorionicity-amnionicity configuration?

Accepted Answer

Trichorionic-triamniotic

Answer

Dichorionic-triamniotic

Answer

Monochorionic-triamniotic

Answer

Monochorionic-diamniotic plus one dichorionic sac

Question 5

What is the standard recommended ultrasound surveillance interval for uncomplicated monochorionic-diamniotic (MCDA) twin pregnancies to screen for TTTS?

Accepted Answer

Every 2 weeks starting from 16 weeks of gestation

Answer

Every 4 weeks throughout the second trimester

Answer

Every week starting at 20 weeks

Answer

Monthly until 28 weeks then biweekly

Question 6

Acardiac twinning (twin reversed arterial perfusion — TRAP sequence) occurs exclusively in which type of twin pregnancy?

Accepted Answer

Any monochorionic twin pregnancy regardless of amnionicity

Answer

Dichorionic-diamniotic twins only

Answer

Monochorionic-diamniotic twins only

Answer

Monochorionic-monoamniotic twins only

Question 7

When counting membrane layers to confirm chorionicity, how many layers does a dichorionic-diamniotic inter-twin membrane contain?

Accepted Answer

4 layers (two amnions and two chorions)

Answer

2 layers (one amnion from each twin)

Answer

3 layers (two amnions and one chorion)

Answer

1 layer (fused amnion)