Ultrasound-indicated cerclage: does expedited placement prolong gestation?

Background

There is no clear consensus on the urgency of ultrasound-indicated cerclage placement after sonographic diagnosis of a short cervix, and it remains uncertain whether immediate cerclage placement prolongs gestation and improves pregnancy outcomes compared to scheduling within a reasonable timeframe.

Objective

This study aimed to determine whether the time interval between the sonographic diagnosis of a short cervix and transvaginal cerclage placement is associated with gestational age at delivery and preterm birth.

Study Design

This retrospective cohort study included all patients who received an ultrasound-indicated cerclage between January 2018 and December 2023 within a large New York health system. Patients were categorized into two groups: those with a history of preterm birth and a short cervix (<25 mm) and those with no prior preterm birth but a very short cervix (<10 mm). The primary exposure was the time interval between diagnosis of a short cervix (ie, decision for cerclage) and cerclage placement, with expedited placement defined as within 1 day for patients without prior preterm birth, and within 5 days for those with prior preterm birth. These cutoffs were determined based on the median time-to-cerclage (days) observed within our study population for each cohort and rounded to the nearest day. The primary outcome was gestational age at delivery, with secondary outcomes including latency to delivery, as well as preterm birth at <37, <34, and <32 weeks. Statistical analyses included linear mixed model regression and multivariate logistic regression, adjusting for body mass index, gestational age at diagnosis, and shortest cervical length prior to cerclage. Data were analyzed using R version 4.3.1. Statistical significance was defined as P<.05.

Results

A total of 125 patients were included, with 83 having a cervical length <10 mm and no prior preterm birth, and 42 having a cervical length <25 mm with a history of preterm birth. In the group without a prior preterm birth, the mean cervical length before cerclage was 6.3±2.4 mm, and the mean gestational age at cerclage placement was 21.0±1.7 weeks. Overall, 74.7% received expedited cerclage placement (≤1 day), while 25.3% underwent routine placement. Gestational age at delivery and preterm birth rates were similar between the expedited and routine placement groups. In the group with a history of preterm birth, the mean cervical length before cerclage was 18.2±5.8 mm, with cerclage placed at a mean gestational age of 19.8±2.6 weeks. Overall, 45.2% underwent expedited placement (≤5 days), while 54.8% had routine placement. A statistically significant difference in gestational age at delivery was observed between groups (36.9±2.5 weeks vs 36.9±3.0 weeks, P=.04), but this difference was not clinically meaningful.

Conclusion

Overall, expedited cerclage placement did not improve pregnancy outcomes in either group, suggesting that immediate placement may not be necessary and that scheduling within a reasonable timeframe is appropriate.