Comparison of indomethacin and nifedipine regarding ductus arteriosus Doppler findings after laser therapy for monochorionic diamniotic twin-to-twin transfusion syndrome: A retrospective cohort study.

Abstract

Background: Indomethacin is administered to reduce preterm labor after fetoscopic laser photocoagulation (FLP) of placental anastomoses.

Objective: To compare ductus arteriosus (DA) Doppler findings in monochorionic diamniotic twin pregnancies complicated by twin-to-twin transfusion syndrome following FLP between cases treated with indomethacin and those treated with nifedipine.

Materials and methods: In this retrospective cohort study, data of 86 pregnant women aged 17-41 yr who underwent FLP in Shariati hospital, Tehran, Iran from October 2024-November 2025 were extracted from medical records and then followed up. In the study, based on pulse rate, the cases were placed in one of 2 groups: nifedipine (pulse rate $<$ 100) and indomethacin (pulse rate $>$ 100) for 48 hr. In cases receiving indomethacin, 6 cases developed DA constriction. A comprehensive fetal echocardiography was performed to assess the status of the DA before and after FLP.

Results: Peak systolic velocity was higher in both donor (145.7 $\pm$ 32.2, p = 0.012) and recipient twins (147.2 $\pm$ 23.6, p = 0.010) in the constricted group compared with the non-constricted groups. In recipient twins, end-diastolic velocity mean was also significantly increased (32.0 in the constricted, 19.9 in the indomethacin, and 18.7 in the nifedipine group, p = 0.012), while pulsatility index mean was significantly lower in the constricted group (1.8, 2.6, 2.5, respectively, p = 0.010).

Conclusion: DA constriction is associated with significant changes in blood flow indices, a higher incidence of right ventricular dysfunction, and a greater prevalence of valvular regurgitation. In this study, fetal DA constriction resolved during the short-term follow-up period.