Fetal thrombotic vasculopathy in twin placentas with complete hydatidiform mole.

Complete hydatidiform mole with a coexistent normal twin is rare, but the mortality rate for the coexistent twin is high, usually attributed to preeclampsia or vaginal bleeding. Placental examination of 3 twin pregnancies complicated by complete hydatidiform mole revealed significant abnormalities in the fetal vasculature. In 1 case, an intrauterine demise at 27 weeks, the placenta showed chorionic plate vessels with mural fibrin thrombi. The placenta from a second case, delivered at 30 weeks for preterm labor, showed similar thrombi in chorionic plate vessels, accompanied by calcification. A third case delivered at 35 weeks produced a liveborn infant, and the placenta showed villous stromal-vascular karyorrhexis, avascular villi, and stem villous thrombosis. Fetal placental thrombotic lesions seen in the coexistent twin circulation, associated with a complete hydatidiform mole, may play a heretofore unrecognized role in the morbidity and mortality of the fetus.