MCDA twins. Posterior placenta.
Twin A (donor):
Cephalic presentation. Oligohydramnios with deepest vertical pocket measuring only 0.7 cm.
Reduced MCA pulsatility index. Intermittent absent end diastolic flow within the umbilical artery. MCA S/D ratio (2.1) less than umbilical artery S/D ratio (4.5).
Twin B (recipient):
Cephalic presentation. Polyhydramnios with deepest vertical pocket measuring 10.6 cm. Large bladder. No hydrops.