Cerclage for short cervix ≤20 mm before 24 weeks in singleton gestations without prior spontaneous preterm birth decreases preterm birth: a meta-analysis of randomized controlled trials using individual patient-level data

Abstract

OBJECTIVE: To evaluate the efficacy of cervical cerclage in preventing preterm birth (PTB) in asymptomatic singleton pregnancies without prior spontaneous PTB and with a mid-trimester short transvaginal ultrasound cervical length (TVU CL). DATA SOURCES: MEDLINE, ClinicalTrials.gov, and the Cochrane Central Register of Controlled Trials were searched for the following terms: "cerclage," "cervical cerclage," "salvage," "rescue," "emergency," "ultrasound-indicated," "short cervix," "cervical length," "ultrasound," and "randomized trial," from inception of each database until November 2024. No language restrictions were applied. STUDY ELIGIBILITY CRITERIA: We included all randomized controlled trials (RCTs) of asymptomatic singleton pregnancies without prior spontaneous PTB screened with TVU CL, found to have a midtrimester short CL ≤25.9 mm, and then randomized to management with either cerclage or no cerclage. We contacted corresponding authors of all the included trials to request access to the data and perform a meta-analysis of individual patient data. STUDY APPRAISAL AND SYNTHESIS METHODS: Individual patient data from the original RCTs were merged into a master database specifically constructed for the review. The primary outcome was PTB <37 weeks. The summary measures were reported as relative risk (RR) or as mean difference (MD) with 95% confidence interval (CI). To obtain the pooled risk ratio estimate the random effects model of DerSimonian and Laird were used RESULTS: Six trials, including 507 asymptomatic singleton gestations without prior spontaneous PTB and with short mid-trimester TVU CL ≤25.9 mm, were included in the meta-analysis. The overall risk of bias of the included trials was judged as low. The primary outcome, PTB <37 weeks, occurred in 89/266 (33.5%) vs 96/241 (39.8%) in the cerclage vs no cerclage group, respectively (RR 0.88, 95% CI 0.59-1.31). Planned subgroup analyses revealed that in patients with CL ≤20.9 mm before 24 weeks, cerclage was associated with a significant decrease in PTB <37 weeks (56/181 (30.9%) vs 66/159 (41.5%); RR 0.75, 95% CI 0.56-0.99) and a significantly longer latency from randomization to delivery (P=.049). CONCLUSIONS: In individuals with singleton gestations, without prior spontaneous PTB and with a short TVU CL in the second trimester, cerclage is associated with a significant decrease in PTB <37 weeks and a significant longer latency at TVU CL ≤20.9 mm before 24 weeks, but not an overall effect on TVU CL ≤25 mm. El resumen está disponible en Español al final del artículo.

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