Objective:To assess the safety and efficacy of radiofrequency ablation (RFA) in the treatment of twin reversed arterial perfusion (TRAP) sequence.Methods:This was a retrospective study of all TRAP sequence cases treated by RFA in Shanghai First Maternity and Infant Hospital, Tongji University School of Medicine, between January 1, 2012, and December 31, 2018. Perioperative complications, short- and long-term perinatal outcomes, and maternal complications were analyzed by analysis of variance, Kruskal-Wallis test, Chi-square test, or Fisher's exact test. Results:(1) This study recruited 59 pregnant women with an average age of (28.4±4.0) years. The mean gestational age at TRAP sequence diagnosis was (17.0±4.1) weeks, and 23 (39.0%) were diagnosed before 16 weeks. (2) The 59 cases consisted of 45 (76.2%) monochorionic diamniotic (MCDC) twins, five (8.5%) monochorionic monoamniotic (MCMA) twins, four (6.8%) monochorionic triamniotic (MCTA) triplets and five (8.5%) dichorionic triamniotic (DCTA) triplets. Fifty-four cases (91.5%) were acardius acephalus, four (6.8%) were acardius anceps, and one (1.7%) was acardius amorphous. (3) Preterm premature rupture of membranes (PPROM) was a leading complication following RFA with an overall incidence of 25.4% (15/59). PPROM before 28 and at 28-34 gestational weeks occurred in seven (11.9%) and five (8.5%) cases, respectively, leading to fetal loss in six cases. The cumulative incidence of PPROM within one week, two weeks, and one month after RFA was 5.1% (3/59), 6.8% (4/59) and 10.2% (6/59), respectively. No chorioamnionitis, blood transfusion due to hemorrhage, placental abruption, sepsis, bowel perforation, or other maternal complications were reported during or after the procedure. (4) No abnormalities of the nervous system were found in any fetus on postoperative MRI during pregnancy. The mean interval from treatment to delivery was (14.9±7.1) weeks. Twelve pump twins (20.3%) were lost after RFA, while the other 47 (79.7%) were delivered and survived until 28 days after birth, including 18 premature infants and 29 full-term infants. Eight premature infants were admitted to the neonatal intensive care unit (NICU). Intraventricular hemorrhage, neonatal respiratory distress syndrome (NRDS), and NRDS complicated by necrotizing enterocolitis occurred in three different babies who recovered after appropriate treatment. (5) Of the 59 patients, 56 (94.9%) received intrauterine interventions after 16 gestational weeks, and the survival rate of the pump twins was 78.6% (44/56). Three patients (5.1%) received intrauterine interventions before 16 weeks of gestation with all pump twins survived. (6) Of the 45 MCDA twins, 37 (82.2%) survived and were born at a mean gestational age of 38.0 (26.5-41.0) weeks. Three out of the five MCMA twins survived with the median gestational age at birth of 33.5 (32.0-37.0) weeks. Of the nine triplets, seven survived and delivered at the median gestational age of 37.1 (29.2-40.0) weeks. (7) The needle pierced through the placenta during RFA in 23 (39.0%) cases, but not in the rest 36 (61.0%) cases. After excluding four cases opting for pregnancy termination, statistical analysis showed no significant difference in the incidence of PPROM or intrauterine death, or the 28-day survival rate of the pump twins when comparing those cases with the needle going or not going through the placenta. (8) At the final follow-up (December 2019), 47 surviving pump infants were growing normally without any severe neurological sequelae.Conclusions:RFA appears to be a relatively safe and reliable technique in the treatment of TRAP sequence to improve the perinatal outcomes of pump twins.