The Arabin cervical pessary for the prevention of preterm birth in twin-to-twin transfusion syndrome treated by fetoscopic laser coagulation: a multicenter randomized controlled trial

Background: Miscarriage and preterm birth are leading causes of loss and disability in monochorionic twins after laser treatment of twin-twin transfusion syndrome.

Objective: This study aimed to investigate the use of cervical pessary to reduce preterm birth before 32 weeks of gestation in monochorionic diamniotic twin pregnancies after fetal surgery for twin-twin transfusion syndrome.

Study design: In this open-label multicenter randomized trial, pregnant women carrying monochorionic diamniotic twins requiring fetoscopic laser coagulation for twin-twin transfusion syndrome were randomly assigned in a 1:1 ratio to pessary placement or conservative management. The primary outcome was birth before 32 weeks of gestation. The secondary outcomes were birth before 28, 30, 34, or 37 weeks of gestation; preterm premature rupture of membranes; fetal and neonatal survival; and a composite of maternal and neonatal complications. The estimated sample size was 364 patients, with 182 cases in each arm of the study. The analysis was performed according to the intention-to-treat principle. Moreover, 2 interim analyses were planned.

Results: The trial was stopped prematurely after the first planned interim analysis for futility. Overall, 137 women were included in the analysis, 67 in the pessary group and 70 in the conservative management group. Preterm birth before 32 weeks of gestation occurred in 27 of 67 women (40.3%) in the pessary group and in 25 of 70 women (35.7%) in the conservative management group (adjusted odds ratio, 1.19; 95% confidence interval, 0.58-2.47; P=.63). No differences between groups were observed in the rate of deliveries before 28, 30, 34, and 37 weeks of gestation. Overall survival to delivery was 91.2% (125/137) for at least 1 twin, and 70.8% (97/137) for both twins, with no difference between groups. Neonatal survival at 30 days was 76.5% (208/272). There was no difference between the groups in maternal or neonatal morbidity.

Conclusion: In monochorionic diamniotic twin pregnancies requiring fetal therapy for twin-twin transfusion syndrome, routine use of cervical pessary did not reduce the rate of preterm birth before 32 weeks of gestation.