OC03.07: *The effect of entry technique on chorioamniotic membrane separation in fetoscopic laser photocoagulation for Twin–twin transfusion syndrome

Chorioamniotic membrane separation (CAS) is a common complication of fetoscopic laser photocoagulation (FLP) for Twin–twin transfusion syndrome (TTTS). We sought to evaluate the effect of sharp trocar vs Seldinger techniques for uterine entry in FLP for TTTS. The primary outcome was CAS. A retrospective cohort study of monochorionic twins with TTTS necessitating FLP at two tertiary fetal centres from 2012-2020. Seldinger technique was systematically utilised by one centre and sharp trocar entry by the other. Bivariate analyses compared the two entry techniques. 508 cases of FLP for TTTS were included: 278 with Seldinger entry and 230 with sharp entry. The Seldinger group had higher BMI, parity and advanced Quintero stage. Sharp entry had lower rates of CAS (8.8% vs 14.8%; p = 0.036) and preterm delivery at <32 weeks (42.3% vs 58.4%; p = <0.001). Sharp entry had later GA at delivery (33 vs 31 weeks; p = 0.003) and greater interval between intervention and delivery (81 vs 71 days; p = 0.01). Seldinger had increased odds of CAS on univariate analysis (OR [95%CI] = 1.83 [1.03-3.27], p = 0.038). BMI, parity and Quintero stage were not associated with increased odds of CAS. In cases of FLP for TTTS, sharp trocar entry was associated with less CAS, lower rates of preterm birth <32 weeks' and a greater interval between intervention and delivery. Given the retrospective nature, further work is warranted.