Fetal Brain Abnormalities Following Laser Surgery for Twin-to-Twin Transfusion Syndrome: Imaging Patterns and Evolution.

Abstract

Introduction: Severe brain injury has been reported following fetoscopic laser ablation (FLA) for twin-to-twin transfusion syndrome (TTTS), but imaging patterns and temporal evolution remain poorly defined. This study aimed to characterize the progression of severe brain injury after FLA.

Methods: We conducted a retrospective case series of TTTS pregnancies with severe brain injury identified after FLA at the Ontario Fetal Center (June 2023-March 2025). FLA was performed for Quintero stage ≥ II and selected stage I cases. Severe abnormalities were defined as severe intraventricular haemorrhage or destructive lesions. Serial ultrasound and fetal MRI were reviewed and categorized as early (< 4 weeks) or late (≥ 4 weeks) post-FLA.

Results: Fifteen fetuses from 14 pregnancies were identified. Mean gestational age at FLA was 19.7 ± 3.2 weeks; 66.7% were stage III-IV and 60% were donor twins. Early imaging (n = 8) most commonly showed periventricular haemorrhagic infarction (62.5%) and cerebellar haemorrhage (25.0%). Late imaging (n = 13) predominantly demonstrated cerebral volume loss (76.9%), often involving the parietal lobes, with polymicrogyria (38.5%) and Wallerian degeneration (30.8%). Findings remained unchanged after 4 weeks.

Conclusion: Brain injury after FLA evolves from acute haemorrhagic/ischaemic insults to irreversible destructive changes. These preliminary findings suggest a consistent pattern of injury that warrants further prospective study.