Prior ultrasound-indicated cerclage: how should we manage the next pregnancy?

Objective: To determine the subsequent need for cerclage and pregnancy outcome, in women with a prior ultrasound-indicated cerclage.

Study design: Analysis of a prospectively collected database from November 2010 to July 2014 from 15 Preterm Surveillance clinics across the UK was performed. Women with an index and previous singleton pregnancy with an ultrasound-indicated cerclage were eligible for inclusion (n=55). Previous ultrasound-indicated cerclage was defined as cerclage inserted prior to 24 weeks' for cervical length <25 mm as detected by transvaginal ultrasound. Women were managed in their subsequent pregnancy with either history-indicated cerclage, transvaginal ultrasound surveillance of cervical length with cerclage if <25 mm or transabdominal cerclage at the discretion of the physician. Exact logistic regression was used to estimate the odds ratio on the chance of delivery before 34 weeks'. Adjustments were made for major risk factors for prematurity: previous spontaneous preterm birth, previous late miscarriage (16+0 to 23+6 weeks') and previous cervical surgery; both individually and in combination.

Results: Of the 55 eligible women, 23 underwent history-indicated cerclage, 23 underwent transvaginal ultrasound cervical length surveillance and 8 underwent abdominal cerclage in the index pregnancy. Of those that had ultrasound surveillance, 13 (57%) did not require cerclage and all delivered after 34 weeks'. Of those that had a history-indicated cerclage, six delivered before 34 weeks'. Therefore, women that received a history-indicated cerclage had greater risk of preterm birth compared to women that underwent ultrasound surveillance with cerclage insertion only if cervical shortening was detected (OR 0.09 95% CI 0.00-0.74, p=0.02). Adjustments for risk factors for preterm birth did not significantly affect this risk.

Conclusion: In women with prior ultrasound-indicated cerclage, who undergo cervical surveillance in the next pregnancy, the majority will not require intervention for a short cervix. Those women receiving a history-indicated vaginal cerclage were more likely to deliver preterm; this cannot be explained by their risk status. All women receiving an abdominal elective cerclage had good outcomes. Ultrasound surveillance is appropriate in women with a prior ultrasound-indicated cerclage who do not require an abdominal cerclage.