Antenatal cerebral necrosis in monochorionic twins.

Antenatal cerebral white matter necrosis occurs relatively frequently in monochorionic twins, particularly when one twin has died in utero or in the twin-twin transfusion syndrome. A case of antenatal cerebral necrosis in both of liveborn monochorionic twins is presented. It is proposed that placental artery-to-artery or vein-to-vein anastomoses may predispose twin fetuses to hemodynamic instability. Fluctuations in blood pressure or blood volume may then result in cerebral necrosis, without requiring the death of one twin or transfer of a blood-borne factor from one twin to the other.