Physical Exam Indicated Cerclage in Twin Pregnancy: A Randomized Controlled Trial

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Background: Twin pregnancies with dilated cervix in the second trimester are at increased risk of pregnancy loss and early preterm birth; currently there is no proven therapy to prevent preterm birth in this group of women.

Objective: To determine if physical exam indicated cerclage reduces the incidence of preterm birth in asymptomatic women with twin gestations and cervical dilation diagnosed before 24 weeks of pregnancy.

Study design: Multicenter, parallel-group, open-label, randomized controlled trial of women with twin pregnancy, and asymptomatic cervical dilation from 1-5 cm between 16 0/7 to 23 6/7 weeks were enrolled from 7/2015 to 7/2019 in 8 centers. Eligible women were randomized in a 1:1 ratio to either cerclage or no cerclage. We excluded women with: monochorionic-monoamniotic pregnancy, selective fetal growth restriction, twin-twin transfusion syndrome, major fetal malformation, known genetic anomaly, placenta previa, signs of labor, or clinical chorioamnionitis. The primary outcome was the incidence of preterm birth <34 weeks. Secondary outcomes were preterm birth <32, <28 and <24 weeks, interval from diagnosis to delivery, and perinatal mortality. Data were analyzed as intention to treat.

Results: After an interim analysis was performed, the Data Safety Monitoring Board recommended stopping the trial due to significant decrease of perinatal mortality in the cerclage group. We randomized 34 women, four were excluded due to expired informed consent. Seventeen women were randomized to physical exam indicated cerclage and 13 women to no cerclage. Four women randomized to cerclage did not receive the surgical procedure, while no women in the no cerclage group received cerclage. Maternal demographics were not significantly different. All women in the cerclage group also received indomethacin and antibiotics. When comparing cerclage vs no cerclage group, the incidence of preterm birth <34 weeks was significantly decreased: 12/17 (70%) vs 13/13 (100%) (RR: 0.71 95% CI 0.52-0.96), as well as preterm birth <32 weeks 11/17 (64.7%) vs 13/13 (100%) (RR: 0.65 95% CI 0.46-0.92), preterm birth <28 weeks 7/17 (41%) vs 11/13 (84%) (RR: 0.49 95% CI 0.26-0.89) and preterm birth <24 weeks 5/17 (30%) vs 11/13 (84%) (RR: 0.35 95% CI 0.16-0.75). The mean gestational age at delivery was later: 29.05±1.7 vs. 22.5±3.9 weeks (p<0.01); the mean interval from diagnosis of cervical dilation to delivery was longer: 8.3±5.8 vs. 2.9±3.0 weeks (p=0.02). Perinatal mortality was also significantly reduced in the cerclage group 6/34 (17.6%) vs 20/26 (77%), (RR: 0.22 95% CI 0.1-0.5).

Conclusion: A combination of physical exam indicated cerclage, indomethacin, and antibiotics in asymptomatic twin pregnancies before 24 weeks significantly decreases preterm birth at all evaluated gestational ages. Most importantly, cerclage in this population is associated with a 50% decrease in very early preterm birth <28 weeks and with a 78% decrease in perinatal mortality.