Flexible video fetoscopy: feasibility and outcomes of a novel modality for laser therapy in twin-to-twin transfusion syndrome presenting with inaccessible anterior placenta

Introduction: Identification of intertwin anastomosis may be challenging during fetoscopy in cases with complete anterior placenta. The aim of this study was to describe the technique, feasibility and outcomes of flexible video fetoscopy for laser coagulation in monochorionic (MC) twin pregnancies with twin-to-twin transfusion syndrome (TTTS) presenting with inaccessible anterior placenta. Methods: From April 2021 to March 2022, a prospective cohort of consecutive MC twin pregnancies complicated with TTTS, presenting with anterior placenta after 20 weeks was recruited. Cases with inaccessible anterior placenta during standard technique were converted into flexible video fetoscopy for completion of laser coagulation of placental anastomosis using a 270 degrees flexible video endoscope through the same uterine port. Descriptive analysis includes feasibility, remaining anastomoses requiring laser photocoagulation, and perinatal outcomes. Results: A total of 45 pregnancies with TTTS were treated with fetoscopic laser therapy during the 1-year study period. Twenty-one pregnancies presented with anterior placenta after 20 weeks, which, an inaccessible vascular equator was observed in 33.3% (7/21). Flexible video fetoscopy was successfully performed in all 7 cases at a median gestational age of 22+2 (20+0-27+1) weeks+days. Visualization of the entire placental surface, coagulation of selected vessels, and exploration of the entire vascular equator were achieved in all cases. Six cases (85.7%) required additional laser coagulation due to either vascular patency despite initial coagulation with conventional fetoscopy (1/6, 16.7%), and/or remaining non-coagulated anastomoses (5/6, 83.3%). Perinatal survival of at least one twin and both twins was achieved in 85.7%, and 57.1%, respectively. Discussion: Flexible video fetoscopy for completion of laser coagulation of placental anastomosis is feasible and represents a good option for TTTS cases presenting after 20 weeks with inaccessible anterior placenta.