TRAP Sequence Clinical Case: Is a Single Umbilical Artery a Protective Ultrasound Marker for Fetal Heart Failure Development

Twin Reversed Arterial Perfusion (TRAP) sequence is a rare complication in monochorionic pregnancies, often leading to fetal heart failure (FHF) in the pump twin. We present a 17-year-old primigravida with a monochorionic monoamniotic twin pregnancy presented with an acardiac twin, single umbilical artery (SUA), and multicystic placenta appearance. Throughout the pregnancy, the pump twin exhibited normal growth without signs of FHF. The infant was delivered at 34 weeks via cesarean section, healthy and without cardiac anomalies. The nonexistence of an impacted intrauterine fetal development and FHF of the pump twin in our case may be explained by the presence of one umbilical artery, resulting in less blood flow to the parasitic twin, which can be accepted as a protective factor for the pump twin circulation. Our hypothesis-generating finding that SUA may play a protective role in the development of FHF in pump-twin is promising; however, it remains speculative, and further research is needed to confirm the protective role of SUA for pump-twin outcomes in TRAP pregnancies.