Evaluation of the success of fetoscopic laser coagulation in placental vascular anastomoses and the role of fetal vascular Doppler before laser treatment in twin-to-twin transfusion syndrome

Introduction: Twin-to-twin transfusion syndrome (TTTS) is a critical prenatal complication in monochorionic diamniotic twins with a high risk of mortality and neurological sequelae if left untreated. Of the various therapeutic approaches, fetoscopic laser surgery (FLS) has emerged as the predominant treatment modality worldwide. This study evaluates the outcomes and preoperative risks of TTTS treatment via FLS. Methods: In this prospective cohort study, we analyzed 115 consecutive TTTS cases with gestational ages of 16 to 26 weeks, treated with FLS at Shariati Hospital, Tehran, Iran, from 2018 to 2022. The mean gestational ages at the time of laser surgery and delivery were 20.70 +/- 2.21 and 32.18 +/- 4.68 weeks, respectively. Postoperative survival was assessed with Doppler measurements post -laser treatment in all but one case, where amniotic sac rupture led to fetal loss. Results: Postoperative survival rates at 30 days were 32.2% for both twins, 53% for either twin, and 85.2% for at least one twin. A notable correlation was observed between donor twin survival anda fetal weight discrepancy exceeding 25%. Additionally, a higher incidence of absent or reversed end-diastolic velocity in the donor umbilical artery was identified among survivors (p < 0.05), indicating a significant survival benefit with FLS. Conclusions: FLS proved to be an effective intervention for TTTS prior to the 26th week of gestation, with outcomes in this Iranian cohort aligning with those reported in developed countries. This underscores FLS's viability as a primary treatment strategy for TTTS, highlighting the importance of early diagnosis and intervention.