[Acardius in twin pregnancy].

The acardius is a rare but severe congenital anomaly. It occurs only in the context of multiple pregnancies and vascular anastomosis between the involved fetus and a multiple in cases of monochorionic placenta. The prenatal diagnosis of an acardius always has to be presumed in a multiple pregnancy within which a twin pair grow whenever cardiac activity can not be proved echographically. We present an acardius in a spontaneous twin pregnancy and discuss--based upon literature research--pathogenetic mechanisms, pathologic-anatomic and echographic conditions as well as therapeutic approaches in favor of the healthy multiple.