334 Influence of cervical length change after laser surgery for twin-twin transfusion syndrome on pregnancy outcomes

Abstract

Twin pregnancies complicated by twin-twin transfusion syndrome (TTTS) are at especially high risk of preterm birth. Cases that have selective fetoscopic laser photocoagulation (SFLP) at our institution undergo transvaginal ultrasound (TVUS) measurement of cervical length (CL) before and after SFLP to assess preterm birth risk during the perioperative period Retrospective cohort study comparing pre- and post-op TVUS CL in pregnancies that underwent SFLP at a single center from 4/2010-6/2019. Among 626 SFLP cases, 476 had data on both pre- and post-op CL and comprised the study cohort. Pre-op TVUS CL was obtained <30 days prior to SFLP, and post-op measure was obtained 0 to 5 days after SFLP. Change in cervical length was defined as pre-op CL minus post-op CL. No change in pre- to post-op CL was defined as a change of <0.5 mm Among 476 patients, n=309(64.9%) experienced net decrease in CL, 54(11.3%) had no change and 113(23.7%) had net increase in CL following SFLP. The mean pre-op CL was significantly longer in cases that had net increase in CL after SFLP compared to those that decreased, 4.59cm vs 3.53cm, p=0.0001. There was no difference in mean DVP of the recipient or latency to delivery among groups (mean 10 wks, p=0.606), Table 1. Cases with a net increase in CL after SFLP had lower rates of preterm birth (PTB) <28 and <32 wks. Decrease or no change in CL after SFLP had no significant influence on PTB rates even when accounting for short pre-op CL, Table 2. Short cervix pre-op in combination with CL change was not significantly associated with PTB Increase in cervical length after SFLP is associated with reduced risk of early preterm birth. It has previously been hypothesized that intraoperative amnioreduction of recipient polyhydramnios may decrease PTB by decreasing uterine stretch, however our data did not show differences in mean DVP with respect to CL change. The mechanisms that influence CL changes in the SFLP perioperative period and influence preterm parturition warrant further investigationView Large Image Figure ViewerDownload Hi-res image Download (PPT)