Gestational age-related risk of rupture of membranes in the setting of fetoscopy for twins

Abstract

To describe, in twin pregnancies, the gestational age-related risk of postoperative rupture of membranes (ROM) < 34 weeks when fetoscopic surgery occurs from 16-26 weeks. Retrospective cohort study of twin pregnancies that underwent fetoscopy at a single fetal center from April 2010 to June 2019. Inclusion criteria was any twin pregnancy in which fetoscopic surgery was performed between 16-26 weeks. Exclusion criteria was aneuploidy, major congenital anomalies, higher order multiples. This study received IRB approval. Pregnancies were stratified by the week of fetoscopy. Primary outcome was the risk of ROM < 34 weeks gestation. Given that earlier surgery carries a longer latency between surgery and 34 weeks, to further measure the risk of ROM, Logrank analysis was used to evaluate the probability of having intact fetal membranes in the 8 weeks immediately post-op. For this analysis, surgeries were grouped into 3 gestational age ranges: surgery < 20 weeks, surgery from 20 0/7-22 6/7 weeks, and surgery from 23-25 6/7 weeks. 696 pregnancies met inclusion. 221 (32%) experienced ROM < 34 weeks. 118 (17%) experienced ROM within 8 weeks of fetoscopy. The risk of ROM with each week of gestation, as well as the 95% CI estimates are listed in table 1. There was a statistically significant decrease in ROM prior to 34 weeks when surgery occurred beyond 20 weeks gestation. Evaluating the probability of pregnancies having continued intact membranes in the 8 weeks immediately post-op revealed an intact membrane rate of 78% (95% CI 72-82%) when surgery occurred < 20 weeks, 87% (95% CI 82-90%) when surgery occurred between 20-22 6/7 weeks, and 79% (95% CI 71-85%) when surgery occurred between 23-25 6/7 weeks (p < 0.001), figure 1. The risk of ROM < 34 weeks decreases when fetoscopy occurs after 20 weeks. Compared to < 20 weeks, there is a lower risk of ROM in the subsequent 8 weeks when surgery occurs between 20-22 6/7 weeks. Interestingly, when surgery occurred < 20 weeks compared to 23-25 6/7 weeks, there was no difference in the risk of ROM in the 8 weeks immediately post-op.View Large Image Figure ViewerDownload Hi-res image Download (PPT)