Early prenatal sonographic diagnosis of twin triploid gestation presenting with fetal hydrops and theca-lutein ovarian cysts.

The presence of theca-lutein ovarian cysts in the early second trimester of pregnancy is highly suspicious for a complete hydatidiform molar pregnancy but can be seen in association with a partial mole. Theca-lutein cysts may occur following hormonal stimulation for assisted reproductive techniques or in association with multiple gestations. Rare causes include immune and nonimmune fetal hydrops, maternal hypothyroidism, and triploid gestations. We report a case of a monochorionic twin gestation in which prenatal sonography demonstrated multiple anomalies and hydrops in each twin and bilateral theca-lutein ovarian cysts. Triploidy in both twins and a partial hydatidiform mole were confirmed at pathologic examination.