TRAP Sequence - An Interesting Entity in Twins

Twin reversed arterial perfusion (TRAP) sequence, is a rare malformation occurring in monozygotic multiple gestations. One well-developed normal (pump) twin and the other twin with absent cardiac structure (acardiac), who is hemodynamically dependent on the normal (pump) twin are characteristic of this syndrome. The acardiac twin develops multiple anomalies that make survival difficult. The prognosis of the pump twin is variable with mortality rate ranging from 50% to 70%. Complications that affect the prognosis of the pump twin include complications of congestive cardiac failure due to increased cardiac demand, prematurity secondary to preterm delivery, and polyhydramnios. Because of these complications prompt detection, follow-up, and treatment of this condition is very important. We report two cases of TRAP sequence that emphasizes the importance of gray-scale and color Doppler imaging in diagnosis, detection of poor prognostic features, follow-up, and management of TRAP sequence.