Pseudoamniotic Band Sequence Risk Factors following Fetoscopic Laser for Twin-Twin Transfusion Syndrome

Introduction: Pseudoamniotic band sequence (PABS) is a rare but serious complication following fetoscopic laser photocoagulation (FLP) for twin-twin transfusion syndrome (TTTS). We aim to explore associations between perioperative factors and PABS in monochorionic, diamniotic twins undergoing FLP for TTTS.

A secondary analysis was conducted using a prospective cohort of 816 FLP procedures performed between 2011 and 2024 at a single fetal therapy center. All cases had confirmed absence of PABS prior to FLP via ultrasound and fetoscopic evaluation. PABS was diagnosed postnatally or suspected after FLP and confirmed after birth. Clinical and perioperative variables were compared between cases with and without PABS using appropriate two-sample tests, with statistical significance set at p < 0.01 to minimize type I error in a smaller cohort.

PABS occurred in 11 (1.3%) cases, with only 3 (27.3%) identified prenatally and treated with in utero band lysis. Digital amputation occurred in 3 undiagnosed cases. There were no differences in maternal characteristics between groups. Estimated fetal weight discordance (p = 0.003), gestational age at FLP (p = 0.0004), and chorionamnion separation (CAS, p < 0.0001) differed significantly between cases with and without PABS.

Observed associations with perioperative factors, particularly with CAS, may inform detailed post-FLP evaluation for PABS. Early detection of PABS may facilitate prenatal intervention and reduce adverse neonatal outcomes.