Postlaser persistent polyhydramnios after resolution of Twin to Twin Transfusion Syndrome.

Objective: Fluid abnormalities should resolve after fetoscopic laser surgery (FLS) for Twin to Twin Transfusion Syndrome (TTTS), but polyhydramnios occasionally persists. We sought to compare patients with persistent polyhydramnios (PP) to those with resolved polyhydramnios (RP) after FLS for TTTS. Methods: Single-center retrospective review of monochorionic twins who underwent FLS for TTTS from June 2014 to January 2024. Patients with RP had resolution of polyhydramnios ≤ 14 days after FLS. PP patients had a maximum vertical pocket (MVP) ≥ 8 cm in the former TTTS recipient > 14 days after FLS. Patients with septostomy, global membrane separation, membrane rupture within 2 weeks of laser, early recipient demise ≤ 14 days after FLS, TTTS recurrence, or undergoing repeat FLS were excluded. Pretreatment characteristics and birth outcomes were compared between PP and RP groups via Pearson or Fischer's exact chi-squared and Mann-Whitney Results: A total of 317 out of 336 (94.3%) patients had RP after FLS, and 19 (5.7%) patients had PP. PP recipients had higher pre-FLS MVP (12.5 vs. 10.0 cm, Conclusion: PP occurred in 5.7% of patients after FLS for TTTS. Resolution of PP occurred in 94.4% of PP patients in a median of 28 days and was not associated with adverse obstetric outcomes. The trend of increased incidence of recipient pyelectasis suggests delayed resolution of recipient polyuria as a potential etiology of PP.