Twin reversed arterial perfusion sequence in a monochorionic monoamniotic twin pregnancy: a very rare condition

Background: Twin reversed arterial perfusion sequence (TRAP) is a very rare congenital anomaly. We present sonographic findings of TRAP sequence in the case of a multiparous woman with a monochorionic monoamniotic twin pregnancy who was referred to our unit for blood sugar control. Case presentation: The patient had a history of co-twin demise at 13 weeks of gestation without appropriate fetal surveillance afterwards. We found a monochorionic placentation with a normal appearing pump twin, an abnormal appearing co-twin without obvious cardiac activity and reversed arterial flow toward instead of away from the anomalous acardiac fetus. Therefore, the sonographic diagnosis of TRAP sequence was confirmed. Conclusions: We recommend considering the potential rare complications of monochorionic twin pregnancy which necessitates proper surveillance and intervention to monitor suitable growth of pump twin.