Safety of radiofrequency ablation for fetal reduction in monochorionic twin pregnancies over 26 weeks of gestation

Objective To investigate the efficacy and safety of radiofrequency ablation for fetal reduction in monochorionic twin pregnancies at gestational age over 26 weeks. Methods A retrospective study was performed based on the clinical data of 51 patients who underwent fetal reduction by radiofrequency ablation in the First Affiliated Hospital of Chongqing Medical University from May 2013 to July 2018. Clinical data including basic information, surgical data (such as ablation duration, power and the number of cycles), perinatal complications and pregnancy outcomes were collected. Differences in pregnancy outcomes were compared between the group with gestational age >26 weeks (n=17, group A) and that ≤26 weeks (n=34, group B) using t-test, rank-sum test and Chi-square test or Fisher's exact test. Results (1) The indications of fetal reduction were malformation in one of the twins, twin-to-twin transfusion syndrome, twin reversed arterial perfusion sequence and selective intrauterine growth restriction [45.1% (23/51), 15.7% (8/51), 19.6% (10/51) and 19.6% (10/51)]. The differences in the proportion of different indications between group A and B were statistically significant [12/17, 1/17, 0/17, 4/17 vs 32.4% (11/34), 20.6% (7/34), 29.4% (10/34), 17.7% (6/34), P=0.009]. Those in the group A required longer operation duration than the group B [M(min-max), 20(7-40) vs 15(3-29) min, Z=2.550, P=0.011]. (2) The gestational age of the 51 patients was (23.7±4.7) weeks (15+1-32+6 weeks), the overall survival rate of the remaining fetuses was 86.3% (44/51) and the preterm birth rate was 50.0% (22/44). The gestational age at operation was (28.9±2.5) weeks (26+1-32+6 week) in group A and (21.1±3.1) weeks (15+1-25+2 weeks) in group B. The survival rate of the remaining fetuses and the preterm birth rate in group A were significantly higher than those in group B [17/17 vs 79.4% (27/34), P=0.046; 12/17 vs 37.0% (10/27), χ2=4.697, P=0.030]. Conclusions Fetal reduction at gestational age >26 weeks, of which the main surgical indication is malformation in one of the twins, may increase the risk of preterm birth, but can improve the overall survival rate of the remaining fetuses without increasing the maternal and infant morbidity. Therefore, radiofrequency ablation is a safe and effective procedure for twin pregnancies >26 weeks of gestation. Key words: Pregnancy, twin; Pregnancy reduction, multifetal; Radiofrequency ablation; Pregnancy trimester, second