Outcomes of Intrauterine Interventions in Twin Reversed Arterial Perfusion (TRAP) Sequence: A Systematic Review of the Literature Over the Past 35 Years

Twin reversed arterial perfusion (TRAP) sequence is an uncommon disease affecting monochorionic twin pregnancies. The diagnosis can be made by ultrasound allowing to plan optimal antenatal management. An electronic search was conducted from inception to July 2024 to systematically evaluate and compare the outcomes of different intrauterine interventions in this condition. Eighty-two studies were included, and 859 women with a prenatal ultrasound diagnosis of TRAP sequence with a total of 1763 fetuses were studied. The mean maternal age was 24.2 years (range 19-40) and the mean gestational age at diagnosis was 19.6 weeks (range 10-32). A total of 792 pregnancies were reported in which a fetal intervention was performed over the past 35 years. The mean gestational age at fetal intervention was 22.1 weeks (range 11-32). The two most frequent fetal interventions were radiofrequency ablation, performed in 293 cases and laser umbilical cord coagulation in 140 cases. Overall, 684 out of 828 non-acardiac fetuses following fetal intervention survived (82.6%) compared with 49 out of 76 (64.5%) non-acardiac fetuses in pregnancies managed expectantly (p = 0.0001). A higher survival rate was seen in fetuses undergoing umbilical cord ligation (100%) although this procedure was performed in only 8 women. Survival rates were 88.9%, 79.9%, 78.9% and 77.9% for monopolar coagulation of the umbilical cord, laser coagulation of the umbilical cord, fetoscopic laser ablation of placental anastomoses and radiofrequency ablation, respectively. Our results show that the survival rate is higher in patients with TRAP who have a prenatal intervention compared with those who have prenatal expectant management. The survival rate varies depending on the modality used for the prenatal intervention. Future studies are necessary to investigate the impact of the gestational age at the time of the procedure on the survival rate depending on the prenatal therapeutic modality.