Acardius anceps: report of 3 cases.

Acardius anceps is an uncommon but serious consequence of multiple pregnancy, usually in monozygotic twins. There are great variations in gross appearance and pathologic features. Recently we have encountered 3 cases of acardius anceps in 3 sets of twin pregnancy. The subcutaneous edema was so extensive and severe that no facial structures could be recognized; however, the skull bones could be detected by prenatal ultrasound examination and confirmed by postnatal radiography. The hearts were all severely malformed and many of the visceral organs were also defective. Prenatal blood gas analysis in 2 affected fetuses showed severe hypoxemia. All 3 pregnancies were terminated before the normal co-twin reached viability. One set of the twins was delivered by hysterotomy because of the potential dystocia caused by bulky fetal mass due to severe hydropic change. Prenatal ultrasound examination is a very useful tool in the diagnosis and management of this anomaly.