twin reversed arterial perfusion (trap) sequence; characteristic gray-scale and doppler ultrasonography findings

twin reversed arterial perfusion (trap) sequence is a syndrome with poor prognosis, seen only in monochorionic monozygotic twin pregnancies. the incidence is one in 35.000 births and one in 100 monozygotic twin pregnancies. it is characterized with a recipient fetus exhibiting lethal anomalies including acardia and a pump fetus. mortality is usually due to heart failure or premature labor caused by polyhydramnios of pump fetus. herein, we report a case of trap sequence that emphasizes the importance of gray-scale and color doppler imaging in the diagnosis and management of trap sequence.