Cervical stitch (cerclage) for preventing preterm birth in singleton pregnancy

Cervical cerclage is a well-known surgical procedure carried out during pregnancy. It involves positioning of a suture (stitch) around the neck of the womb (cervix), aiming to give a mechanical support to the cervix and thereby reducing the risk of preterm birth. The effectiveness and safety of this procedure remains controversial.

To assess whether the use of cervical stitch in singleton pregnancy at high risk of pregnancy loss based on a woman's history and/or ultrasound finding of 'short cervix' and/or physical exam improves subsequent obstetric care and fetal outcome.

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 October 2011) and reference lists of identified studies.

We included all randomised trials of cervical suturing in singleton pregnancies carried out when pregnancy was considered to be at sufficiently high risk of pregnancy loss for cerclage to be potentially indicated. We included any study that compared cerclage with either no treatment or any alternative intervention.

Three review authors independently assessed trials for inclusion. Two review authors independently assessed risk of bias and extracted data. Data were checked for accuracy.

We included 12 trials (involving 3328 women). When cerclage was compared with no treatment, there was no statistically significant difference in perinatal deaths (8.4% versus 10.7%) (risk ratio (RR) 0.78; 95% confidence interval (CI) 0.61 to 1.00; eight trials, 2391 women) and neonatal morbidity (9.6% versus 10.2%) (RR 0.95; 95% CI 0.63 to 1.43; four trials, 818 women), despite significant reduction in preterm births (average RR 0.80; 95% CI 0.69 to 0.95; nine trials, 2898 women). Cervical cerclage was associated with the higher rate of maternal side effects (vaginal discharge and bleeding, pyrexia) (average RR 2.25; 95% CI 0.89 to 5.69; three trials, 953 women). Caesarean section rates were significantly higher after cervical cerclage (RR 1.19; 95% CI 1.01 to 1.40; 8 trials, 2817 women).There was no evidence of any important differences across all prespecified clinical subgroups (history-indicated, ultrasound-indicated)One study that compared cerclage with weekly intramuscular injections of 17 α-hydroxyprogesterone caproate in women with a short cervix detected by transvaginal ultrasound, failed to reveal any obvious differences in obstetric and neonatal outcomes between the two management strategies.Two studies compared the benefits of performing cerclage based on previous history with cerclage, only if the cervix was found to be short on transvaginal ultrasound. There was no significant difference in any of the primary and secondary outcomes.

Compared with no treatment, cervical cerclage reduces the incidence of preterm birth in women at risk of recurrent preterm birth without statistically significant reduction in perinatal mortality or neonatal morbidity and uncertain long-term impact on the baby. Ceasarean section is more likely in women who had cervical suture inserted during pregnancy.The decision on how best to minimise the risk of recurrent preterm birth in women at risk, either because of poor history of a short or dilated cervix, should be 'personalised', based on the clinical circumstances, the skill and expertise of the clinical team and, most importantly, woman's informed choice.