The effectiveness of ultrasound-indicated cerclage for the reduction of extreme preterm birth in twin pregnancies with a short cervix: a systematic review and meta-analysis

Abstract

OBJECTIVE

This study aimed to evaluate the effectiveness of cervical cerclage in women with a twin pregnancy and a midpregnancy asymptomatic short cervix (≤25 mm), in preventing preterm birth and improving neonatal outcomes.

DATA SOURCES

Systematic searches were conducted in MEDLINE, Embase, Web of Science, Scopus, and Cochrane Library up to April 17, 2023, updated in September and February 2024.

STUDY ELIGIBILITY CRITERIA

Included were randomized controlled trials, cohort studies, and case-control studies comparing cerclage with expectant management in twin pregnancies and an asymptomatic short cervix (≤25 mm).

METHODS

Risk of bias was assessed using the Newcastle-Ottawa Quality Assessment Scale and the Risk of Bias 2 tool. Data were analyzed using RevMan 5.4 using a random-effects model.

RESULTS

Three randomized controlled trials and 13 cohort studies, involving 696 cerclage patients and 595 controls, were analyzed. Combined randomized controlled trial findings (N=49) found no significant difference in preterm birth occurrence after adjustment for preterm birth history and gestational age. Neonates from cerclage-treated mothers exhibited significantly higher rates of respiratory distress syndrome (adjusted odds ratio, 3.88; 95% confidence interval, 1.09–21.03) and very low birthweight (adjusted odds ratio, 2.22; 95% confidence interval, 1.07–5.73). In contrast, pooled cohort data indicated significantly less preterm birth rates in women with a cerclage: at 34 weeks (relative risk, 0.75; 95% confidence interval, 0.63–0.90), 32 weeks (relative risk, 0.67; 95% confidence interval, 0.49–0.90), and 28 weeks (relative risk, 0.572; 95% confidence interval, 0.39–0.83). Cerclage also reduced risk for infants <1500 g, respiratory distress syndrome, admission at the neonatal intensive care unit, and sepsis. Women with cervical length <15 mm and a cerclage experienced fewer preterm birth rates at <37 weeks (relative risk, 0.88; 95% confidence interval, 0.81–0.94), 34 weeks (relative risk, 0.70; 95% confidence interval, 0.57–0.87), 32 weeks (relative risk, 0.63; 95% confidence interval, 0.50–0.80), and 28 weeks (relative risk, 0.43; 95% confidence interval, 0.32–0.59). Perinatal mortality risk was significant lower in neonates born to mothers with a cerclage. For women with cervical length between 16 and 25 mm, no significant differences in outcomes were observed.

CONCLUSION

Based on our meta-analysis, cerclage may benefit women with a twin pregnancy with an asymptomatic midpregnancy short cervix <25 mm, especially in women with a cervix <15 mm, by reducing preterm birth and improving neonatal outcomes. However, the differences between randomized controlled trials and recent cohort studies emphasize the need for well-powered randomized controlled trials on neonatal outcomes before introducing cerclage in clinical practice for these women.