513 Elective fetal reduction in monochorionic diamniotic(MCDA) twins decreases adverse outcomes compared to ongoing MCDA twins

Abstract

Multifetal Pregnancy Reduction (MPR) is a technique used to reduce the fetal number with the goal of mitigating the risk of adverse outcomes, specifically preterm birth (PTB). MCDA twins are subject to unique complications which contribute to adverse pregnancy outcomes. Our objective was to compare outcomes of elective reduction of MCDA twins by radiofrequency ablation (RFA) to planned ongoing MCDA twins. We performed a retrospective review of 315 MCDA twin gestations that underwent first-trimester ultrasound at two practices within one institution. Planned elective reduced twins were compared with planned ongoing MCDA twins. The primary outcome was PTB less than 34 weeks. Secondary outcomes included PTB < 37 weeks, unintended loss, and adverse maternal and neonatal outcomes. Among 375 identified MCDA twins, complete follow-up data was available for 315 patients(84%). Of these pregnancies, 14(4.4%) underwent elective MPR and 301(95.6%) were planned ongoing twins. Patients who underwent elective MPR had significantly higher maternal age(p < 0.01) and were more likely to be of Asian race/ethnicity(p < 0.01) compared to patients with ongoing twins. They were also more likely to have undergone IVF(p=0.03) and chorionic villus sampling(p < 0.01). Patients with ongoing pregnancies had an 8-fold risk of PTB < 37 weeks compared to elective RFA patients(OR 8.0, 95% CI 2.4-26.4; p < 0.01) although no difference in PTB < 34 weeks. All patients who underwent elective RFA had successful pregnancies with no pregnancy losses or terminations. Twenty-two patients(7.3%) with planned ongoing twins had total pregnancy loss < 24 weeks, 24(8%) had unintended pregnancy loss < 24 weeks, 16(5.3%) underwent a medically indicated RFA and 5(1.7%) had intrauterine fetal demise(IUFD) > 24 weeks. There was no significant difference in loss rates between the two groups. In this study of MCDA twins, patients who elected to undergo MPR had lower rates of PTB < 37 but not < 34 weeks without an increased risk of pregnancy loss. Further research is needed to clarify if MPR improves long term outcomes.View Large Image Figure ViewerDownload Hi-res image Download (PPT)