Twin reversed arterial perfusion syndrome.

Twin reversed arterial perfusion (TRAP) syndrome is a rare but severe complication of monozygotic monochorionic twin pregnancies. The outcome is invariably fatal for the abnormal twins and for 50-75% of the normal co-twins. The prenatal diagnosis of the TRAP always has to be presumed in a multiple pregnancy within which a twin pair grows whenever cardiac activity can not be proved echographically. We present discuss--based upon literature research--pathogenic mechanisms, pathologic-anatomic, echographic diagnosis and management of these high-risk pregnancies.