P09.22: Perinatal outcomes following radiofrequency ablation in monochorionic pregnancies

Selective fetal reduction in monochorionic (MC) pregnancies requires vaso-occlusive procedures to ablate umbilical cord blood flow to achieve asystole of the targeted fetus. We describe the perinatal outcome of a large series of MC pregnancies following radiofrequency ablation (RFA). This was a prospective study at Queen Charlotte's Hospital, London of all cases of selective fetal reduction in MC pregnancies using RFA between Jan 2008 and Dec 2011. Indications for fetal reduction included discordant structural anomaly, TRAP sequence, discordant aneuploidy, twin to twin transfusion syndrome, multifetal reduction (MFPR) in triplets or higher order MC pregnancies or fetal growth restriction (FGR). Outcomes investigated were: rupture of membranes (ROM) or miscarriage within 2 weeks of the procedure, preterm delivery, co-twin demise, brain injury, fetal and neonatal death. Statistics were calculated with SPSSv.19. 84 cases of RFA were performed (31 for structural anomaly, 9 for TRAP, 20 for TTTS, 2 for aneuploidy, 11 for MFPR, 11 for FGR). The median gestation at RFA was 17.5 weeks (range 12.1–27.6 weeks). The overall live birth rate was 82%. PPROM and/or miscarriage within 2 weeks occurred in 3% of cases respectively. Co-twin IUD occurred in 13% of cases. The median gestation at delivery was 35 weeks (Range 14–41 weeks). The pre-term (< 37 weeks) live birth rate was 45%. The incidence of brain injury following the RFA was 4.5%. Neonatal death occurred in 1.2% of cases. The incidence of co-twin demise appeared greatest (19.2%) when the RFA was performed before 16 weeks compared to after 16 weeks (13.9%), although this did not reach significance (P = 0.082). There were no maternal complications. RFA is a safe technique for selective reduction in MC pregnancies and can be performed much earlier compared with other methods. The risk of co-twin demise appears greatest before 16 weeks gestation.