546 Natural history of previable and periviable rupture of membranes after treatment of twin-twin transfusion syndrome

Abstract

We aim to describe the natural history and outcomes of pre/periviable prelabor rupture of membranes (PROM) in TTTS after selective fetoscopic laser photocoagulation (SFLP). Retrospective cohort study at a single fetal center which included pregnancies from April 2010-June 2019 complicated by TTTS and were treated with SFLP and subsequently had PROM. Primary outcomes were latency from PROM to delivery and fetal survival. Exposure groups were pregnancies that developed PROM between 16-19 6/7 weeks, 20 -22 6/7 weeks, 23- 25 6/7 weeks and ≥ 26 weeks (referent group). Comparisons were made with t-test, Mann-Whitney U, Kruskall-Wallis, and chi-squared as appropriate, with significance reported as p < 0.05. A total of 33% (N=221/678) of patients had PROM post-SFLP. The average latency from SFLP to PROM was 7.5 weeks (95% CI 7.0 – 8.1) with overall 86% survival in setting of PROM. Eighteen patients (2.7%) experienced PROM within 7 days of surgery, with the mean gestational age (GA) at delivery of 23.4 weeks (95% CI 21.2-25.6 weeks) and 44% (8/18) of those patients delivering within 48 hrs. Baseline characteristic among those that experienced PROM < 26 weeks vs ≥ 26 weeks were non-significant except for GA at the time of surgery (19.5 ± 2.1 vs 20.6 ± 2.8 weeks respectively, p=0.005). The rates of PROM by GA were 0.7%, 2.7% and 6.1% at 16-19 6/7, 20-22 6/7, and 23-25 6/7 weeks, respectively. Linear regression demonstrated inverse correlation between GA at PPROM and latency, R = 0.25. Despite this longer latency, those with PROM after SFLP at less than 23 weeks demonstrated lower survival rates as delivery was more likely to occur in the periviable period (Table). These findings remained true when patients who delivered within 48 hours of PROM were excluded. GA at PROM after SFLP is inversely correlated with latency to delivery, however later GA at PROM is associated with improved live birth rates. When latency after PROM exceeds 48 hours, rates of live birth are significantly improved, with live birth of one or more fetuses exceeding 70% even with PROM < 20 weeks.View Large Image Figure ViewerDownload Hi-res image Download (PPT)