Incidence and clinical implications of chorioamniotic membrane separation after fetoscopic surgery in monochorionic twin pregnancies

Objectives: To evaluate the incidence of chorioamniotic membrane separation (CMS) after surgical fetoscopy in monochorionic diamniotic twins and its impact on pregnancy outcome.

Methods: 338 patients with monochorionic diamniotic pregnancies complicated with twin-to-twin transfusion syndrome or selective intrauterine growth restriction that underwent surgical fetoscopy (selective laser photocoagulation of communicating vessels (SLPCV) or cord occlusion) at a single tertiary level hospital during a 6-year period were included. Surgical data included cervical length, gestational age (GA), type of surgery, duration, and placental location. The incidence of CMS, occurrence of miscarriage, preterm premature rupture of membranes (PPROM), GA at delivery, and neonatal survival were also recorded.

Results: Most of the cases (79.9%) were TTTS. SLPCV was performed in 252 (74.6%) cases and cord occlusion in 86 (25.4%). Postoperative CMS was observed in 70 (20.7%) cases. Median GA at surgery was lower in the group of CMS (18.0 (3.7) vs. 20.3 (4.2) weeks, p < 0.001). Patients with CMS had a higher proportion of miscarriage (14.7% vs. 7.1%, p = 0.049), PPROM < 32 weeks (43.1% vs. 13.7%, p < 0.001), preterm delivery < 32 weeks (53.4% vs. 26.0%, p < 0.001), and a lower neonatal survival (at least one survivor 81.0% vs. 93.4%, p = 0.003). No significant differences were found in cervical length, placental location, duration and type of surgery.

Conclusions: CMS is a frequent complication of surgical fetoscopy, even after the learning curve. The occurrence of CMS is associated with a poorer pregnancy outcome and reduces the chances of neonatal survival.