Background: Several observational studies have claimed high success rates for cerclage in women with cervical insufficiency. A recent Cochrane review found no conclusive evidence of benefit, although significant heterogeneity was present for some of the important clinical outcomes.
Objectives: We undertook an individual patient data (IPD) meta-analysis to examine effect of cerclage on neonatal and maternal outcomes. In an attempt to explain the heterogeneity, we investigated whether obstetric factors including multiple gestation are associated with effectiveness.
Search strategy: Search methods described in the original Cochrane review were adopted and updated to December 2005.
Selection criteria: This IPD systematic review and meta-analysis was of randomised trials comparing cervical cerclage during pregnancy with expectant management or no cerclage in women with confirmed or suspected as having cervical insufficiency.
Analysis: Multilevel logistic regression models stratified by trial with random treatment effects were fitted to investigate the impact of obstetric factors and multiple gestation on treatment effect. Primary outcome measures were pregnancy loss or death before discharge from hospital and absence of neonatal morbidity.
Main results: The meta-analysis included seven trials and 2091 randomised women. In singleton pregnancies, the reduction in pregnancy loss or death before discharge from hospital following cerclage failed to reach statistical significance (OR 0.81; 95% CI 0.60-1.10). Cerclage was found to have a detrimental effect on the outcome of pregnancy loss or death before discharge from hospital in multiple gestations (OR 5.88; 95% CI 1.14-30.19), although only a small number of multiple pregnancies were included in the analysis. Neither indication for cerclage nor obstetric history was found to have a statistically significant impact on the effect of cerclage.
Conclusions: Cerclage may reduce the risk of pregnancy loss or neonatal death before discharge from hospital in singleton pregnancies thought to be at risk of preterm birth, but further large trials are needed to elucidate the risk-benefit ratio precisely. Cerclage in multiple pregnancies should be avoided. The efficacy of cerclage was not influenced by either indication for cerclage or mother's obstetric history.