Role of gestational age at time of placental laser surgery in outcome of twin-to-twin transfusion syndrome.

Objective: There are conflicting data on whether fetoscopic laser photocoagulation (FLP) of placental anastomoses for the treatment of twin-to-twin transfusion syndrome (TTTS) is associated with lower rates of overall survival. The objective of this study was to characterize twin survival and associated morbidity according to the gestational age at which FLP was performed.

Methods: This was a secondary analysis of data collected prospectively on patients with a monochorionic diamniotic (MCDA) twin pregnancy who underwent FLP for TTTS at two centers between January 2011 and December 2022. Patients were divided into six groups according to gestational age at the time of FLP: < 18 weeks, 18 + 0 to 19 + 6 weeks, 20 + 0 to 21 + 6 weeks, 22 + 0 to 23 + 6 weeks, 24 + 0 to 25 + 6 weeks and ≥ 26 weeks. Demographic characteristics, sonographic characteristics of TTTS and operative characteristics were compared across the gestational age epochs. Outcomes, including overall survival, preterm delivery (PTD), preterm prelabor rupture of membranes (PPROM), intrauterine fetal demise (IUFD) and neonatal demise (NND), were also compared across gestational age epochs. Multivariate analysis was performed by fitting logistic regression models for these outcomes. Kaplan-Meier curves were constructed to compare the interval from PPROM to delivery between gestational age epochs.

Results: There were 768 patients that met the inclusion criteria. The rate of dual twin survival was 61.3% for cases in which FLP was performed before 18 weeks, compared with 78.0%-86.7% when FLP was performed at ≥ 18 weeks' gestation. This appears to be driven by an increased rate of donor IUFD following FLP performed before 18 weeks (28.0%) compared with ≥ 18 weeks (9.3-14.1%). Rates of recipient IUFD and NND and donor NND were similar regardless of gestational age at FLP. The rate of PPROM was higher for FLP conducted at earlier gestational ages, ranging from 45.6% for FLP before 18 weeks to 11.9% for FLP performed at 24 + 0 to 25 + 6 weeks' gestation. However, gestational age at delivery was similar across gestational age epochs, with a median of 31.7 weeks. On multivariate analysis, donor twin loss was associated with FLP before 18 weeks, even after adjusting for selective fetal growth restriction, Quintero stage and other covariates. PPROM and PTD were also associated with FLP performed before 18 weeks after adjusting for cervical length, placental location, trocar size, laser energy and amnioinfusion.

Conclusions: FLP performed at earlier gestational ages is associated with lower overall survival, which is driven by the increased risk of donor IUFD, as opposed to differences in the rate of PPROM or PTD. Parental counseling regarding twin survival should account for the gestational age at which patients present with TTTS. © 2024 International Society of Ultrasound in Obstetrics and Gynecology.