P15.06: The relationship between perioperative cervical dynamics and the interval to delivery after fetoscopy

Multiple cervical parameters such as cervical length (CL), anterior cervical angle (CA), valsalva induced cervical shortening (VCS), funnelling, and sludge have been proposed as risk factors for earlier delivery. Operative fetoscopy (OF) is associated with significant uterine stimulation and accordingly could trigger changes in cervical dynamics that lead to earlier delivery. It was our aim to evaluate the relationship of multiple cervical parameters to the intervention to delivery interval in women undergoing OF. Patients referred for OF had preoperative transvaginal ultrasound measurement of CL, CA, cervical width, valsalva change in cervical length, funnelling, sludge, and moon sign. Measurements were repeated on postoperative days and weeks 1 and 2, respectively. Preoperative findings and postoperative changes in cervical parameters were related to pregnancy complications and interval to delivery. 62 women underwent OF (49 fetoscopic laser, 8 cord coagulation, 4 tracheal occlusion, 1 cystoscopy) at a medican gestational age of 20.4 weeks (12.7-32.7). The medican OF to delivery interval was 71 days (6-151) for a median gestational age at delivery of 32 weeks (20-39). Excluding 11 women receiving postoperative pessary or cerclage, all cervical parameters for persistent cervical shortening after OF were unaffected by the procedure. Considering multiple intraoperative and cervical parameters, only the intraoperative net difference in amniotic fluid, preoperative CL, and day 1/2 postoperative CL correlated with interval to delivery (Spearman Rho 0.41, 0.39 and 0.32 respectively, all p<0.005). Logistic regression identified need for intraoperative fluid reduction as the primary determinant of a short fetoscopy to delivery interval (r2 0.36, p <0.0016). Uterine distention that is associated with cervical shortening and funnelling leads to a shorter interval to delivery following operative fetoscopy.