Ms. Doe was pregnant with twins; they shared a placenta but had their own amniotic sacs. During her pregnancy, one of the twins, Twin B, had an abnormal velamentous cord insertion and exhibited persistent absent end-diastolic flow, which indicated underlying fetal vascular stress. Velamentous cord insertion is a complication of pregnancy in which the umbilical cord is inserted in the fetal membranes. In a normal pregnancy, the umbilical cord inserts into the middle of the placenta and is surrounded by the amniotic sac.
At 24 weeks, a Doppler ultrasound revealed reverse end-diastolic flow (REDF) in Twin B’s umbilical artery. Reversal of the umbilical artery end-diastolic flow or velocity can be an ominous sign when detected after 16 weeks of pregnancy. In extreme situations, such as severe intrauterine growth restriction, the arterial blood flow can reverse directions at the end of diastole. This is referred to as a reversed end-diastolic flow.
When this condition was recognized, Ms. Doe’s treating maternal-fetal medicine specialist did not hospitalize her but continued seeing her every week until 27 weeks gestation. Two weeks later, Twin B died.