McDonald versus Shirodkar cerclage technique in the prevention of preterm birth. A systematic review and meta-analysis

Background: Cervical cerclage has been used for decades to decrease rates of preterm birth. The Shirodkar and McDonald cerclage are the two most commonly used cerclage techniques with no current consensus on the preferred technique. Objective: To compare the efficacy of the two techniques. Search strategy: Studies were sourced from six electronic databases and reference lists. Selection criteria: Studies including women with a singleton pregnancy, requiring a cervical cerclage, using either the Shirodkar or McDonald technique that ran comparative analyses between the two techniques. Data collection and analysis: The primary outcome was preterm birth before 37 weeks, with sub analyses at 28, 32, 34 and 35 weeks. Secondary data was also collected on neonatal, maternal and obstetric outcomes. Main results: Seventeen papers were included - analysis showed the Shirodkar group had significantly less chance of preterm birth before 37 weeks (RR 0.91, 95% CI 0.85-0.98). This finding is reinforced by statistically significant reduction in rates of preterm birth before 37, 35, 34 and 32 weeks, PPROM (RR 0.87 ,95% CI 0.77 – 0.99), difference in cervical length (mean difference 5.25, 95% CI 4.68–5.83), cerclage to delivery interval (mean difference 10.79, 95% CI 8.20-13.38), and an increase in birthweight (mean difference 348 grams, 95% CI 291–406) in the Shirodkar group. Conclusion: Shirodkar cerclage leads to a significant reduction in preterm birth and delivers better maternal and neonatal outcomes when compared to McDonald cerclage. Funding: No funding was required for this review. Keywords: Cervical, Stitch, Cerclage, McDonald, Shirodkar, Preterm birth