Cervical cerclage for prevention of preterm delivery: meta-analysis of randomized trials

To estimate the effectiveness of prophylactic and therapeutic cerclage by meta-analysis of randomized clinical trials.

We searched the Cochrane Pregnancy and Childbirth Group specialized register of clinical trials (May 2002). Congress proceedings of international society meetings of fetal-maternal and reproductive medicine were searched by hand.

Meta-analysis of randomized clinical trials comparing cervical cerclage with expectant management during pregnancy was performed. Further clarification was sought from trial authors when required.

Six trials describing a total of 2175 women were analyzed. Prophylactic cerclage was compared with no cerclage in four trials. Pooled results failed to show a statistically significant reduction in pregnancy loss and preterm delivery rates, although a small reduction in births less than 33 weeks' gestation was seen in the largest trial (relative risk [RR] 0.75; 95% confidence interval [CI] 0.58 to 0.98). Cervical cerclage was associated with mild pyrexia, increased use of tocolytic therapy, and hospital admission but no serious morbidity. Two trials examined the role of therapeutic cerclage when ultrasound examination revealed a short cervix. Pooled results failed to show a reduction in total pregnancy loss, early pregnancy loss, or preterm delivery before 28 and 34 weeks in women assigned to cervical cerclage.

The effectiveness of prophylactic cerclage in preventing preterm delivery in women at low or medium risk for second-trimester pregnancy loss has not been proven. The role of cerclage in women whose ultrasound reveals short cervix remains uncertain.