Cerclage for women with twin pregnancies: a systematic review and metaanalysis

Objective data: This study was conducted to estimate whether cerclage could extend the prolongation of pregnancy, reduce the risk of preterm birth, and improve perinatal outcomes in women with twin pregnancies.

Study eligibility criteria: We included randomized controlled trials and cohort studies comparing the efficacy of cerclage with no cerclage for women with twin pregnancies.

Study appraisal and synthesis methods: The following databases were searched for all published studies that compared cerclage placement with expectant management in twin pregnancies from inception to July 2018: Medline, EMBASE, Scopus, ClinicalTrials.gov, Web of Science, and Cochrane Library. Each report was reviewed for inclusion or exclusion standard, and data extraction was performed by 2 authors independently.

Results: A total of 16 studies with 1211 women that met the inclusion criteria were included in the final analysis. Our outcomes indicated that cerclage placement for twin pregnancies with a cervical length of <15 mm was associated with significant prolongation of pregnancy by a mean difference of 3.89 weeks of gestation (95% confidence interval, 2.19-5.59; P=.000; I²=0%) and a reduction of preterm birth at <37 weeks of gestation (risk ratio, 0.86; 95% confidence interval, 0.74-0.99; P=.040; I²=0%), <34 weeks of gestation (risk ratio, 0.57; 95% confidence interval, 0.43-0.75; P=.000; I²=0%) and <32 weeks of gestation (risk ratio, 0.61; 95% confidence interval, 0.41-0.90; P=.010; I²=0%), compared with those pregnancies in the control group. For women with a dilated cervix of >10 mm, cerclage placement was associated with significant prolongation of pregnancy by a mean difference of 6.78 weeks of gestation (95% confidence interval, 5.32-8.24; P=.000; I²=0%); a reduction of preterm birth at <34 weeks of gestation (risk ratio, 0.56; 95% confidence interval, 0.45-0.69; P=.000; I²=28%), <32 weeks of gestation (risk ratio, 0.50; 95% confidence interval, 0.38-0.65; P=.000; I²=14%), <28 weeks of gestation (risk ratio, 0.41; 95% confidence interval, 0.20-0.85; P=.030; I²=80%), and <24 weeks of gestation (risk ratio, 0.35; 95% confidence interval, 0.18-0.67; P=.001; I²=24%), and improvement of perinatal outcomes compared with those in the control group. However, for twin pregnancies with a normal cervical length (eg, cerclage for an indication for women with a history of preterm birth or twin alone), the efficacy of cerclage placement was less certain because of the limited data.

Conclusion: Our metaanalysis indicates that cerclage placement is beneficial for the reduction of preterm birth and the prolongation of pregnancy in twin pregnancies with a cervical length of <15 mm or dilated cervix of >10 mm. However, the benefit of history-indicated or twin alone-indicated cerclage is less certain in twin pregnancies with normal cervical length according to current literature. Further high-quality studies were needed to confirm the findings.