A case of TRAP sequence with immense acardiac twin.

Twin-reversed arterial perfusion sequence is a rare complication of monochorionic twin pregnancy in which an anomalous acardiac fetus is hemodynamically dependent on its structurally normal "pump" twin. Early diagnosis is essential for improving perinatal prognosis for the normal twin. In this case report we present a case of TRAP sequence with immense acardiac twin with favorable outcome, emphasizing the importance of ultrasound imaging, follow-up and timing of delivery in this complicated pregnancy.