Twin reversed arterial perfusion sequence, to treat or not to treat? and surgical approaches

Twin Reversed Arterial Perfusion (TRAP) sequence is an infrequent complication of monochorionic pregnancies, characterized by retrograde perfusion of an acardiac twin via arterio-arterial and veno-venous placental anastomoses, leading to severe malformations in the acardiac twin and hemodynamic strain on the pump twin. This narrative review explores the pathophysiology, diagnostic criteria, and prognostic factors influencing management decisions, including acardiac-to-pump twin weight ratio, Doppler abnormalities, and early signs of cardiac dysfunction. Expectant management remains a viable option in low-risk cases with close surveillance, but the presence of poor prognostic indicators-such as hydrops, reversed a-wave in the ductus venosus, or significant polyhydramnios-justifies timely fetal intervention. Surgical techniques such as intrafetal radiofrequency ablation, laser coagulation, and bipolar cord occlusion have demonstrated improved survival for the pump twin, especially when performed in the early second trimester. While minimally invasive approaches have advanced significantly, a prophylactic intervention strategy has gained traction in some centers to prevent unpredictable deterioration. Given the lack of randomized trials and limited long-term outcome data, individualized, gestational age-tailored management remains crucial, and further prospective studies are needed to optimize care in TRAP sequence pregnancies.