Single fetal demise in a twin gestation: umbilical vein thrombosis.

BACKGROUND: Single fetal demise in a twin pregnancy is a rare event, the common causes being twin-twin transfusion syndrome, chromosomal or congenital anomalies and abnormalities of the umbilical cord and placenta. Umbilical vein thrombosis is a very rare cause of single fetal demise in twins. CASE: Three days after a reassuring biophysical profile, a 40-year-old primigravida with twin pregnancy presented at 38 weeks' gestation in early labor when demise of 1 of the twins was recognized. She underwent a cesarean section for arrest of labor, delivering twin A, a stillborn female weighing 2, 360 g and twin B, a liveborn male weighing 2,200 g. Umbilical vein thrombus was noted in twin A.
CONCLUSION: Umbilical vein thrombosis is a rare and sudden cause of fetal demise.