Skip to main content
Open Access Publications from the University of California

UC Irvine

UC Irvine Previously Published Works bannerUC Irvine

Can the optimal cervical length for placing ultrasound‐indicated cerclage be identified?

Published Web Location


To assess a continuum of cervical length (CL) cut-offs for the efficacy of ultrasound-indicated cerclage in women with previous spontaneous preterm birth (PTB).


This was a planned secondary analysis of a multicenter randomized clinical trial of ultrasound-indicated cerclage for the prevention of PTB in high-risk women. The efficacy of cerclage for preventing recurrent PTB < 35, < 32 and < 24 weeks' gestation was assessed using multivariable logistic regression analysis. Odds ratios (ORs) and CIs were estimated for a range of CL cut-offs using bootstrap regression. The 2.5(th) and 97.5(th) percentiles of bootstrapped ORs determined the CIs. Results were illustrated using smoothed curves superimposed on estimated ORs by CL cut-off.


Of 301 women with a CL < 25 mm, 142 underwent ultrasound-indicated cerclage and 159 did not have cerclage placement. The few cases with CL < 10 mm limited the evaluation to CL cut-offs between < 10 mm and < 25 mm. For PTB < 35 weeks, ORs in women with a cerclage and CL < 25 mm were statistically significantly lower than in those without cerclage, and efficacy was maintained at smaller CL cut-offs. Results were similar for PTB < 32 weeks. For PTB < 24 weeks, results differed, with ORs increasing toward unity (no benefit), with wide CIs, for CL cut-offs between < 10 mm and < 15 mm, attributed to the small number of births < 24 weeks.


The efficacy of ultrasound-indicated cerclage in women with previous spontaneous PTB varies by action point CL cut-off and by PTB gestational age of interest. Cerclage significantly reduces the risk of PTB < 35 and < 32 weeks, at CL cut-offs between < 10 mm and < 25 mm, with the greatest reduction at shorter CL, affirming that women with prior spontaneous PTB and a short CL are appropriate candidates for ultrasound-indicated cerclage. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Many UC-authored scholarly publications are freely available on this site because of the UC's open access policies. Let us know how this access is important for you.

Main Content
For improved accessibility of PDF content, download the file to your device.
Current View