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Can the optimal cervical length for placing ultrasound‐indicated cerclage be identified?
Author(s) -
Szychowski J. M.,
Owen J.,
Hankins G.,
Iams J. D.,
Sheffield J. S.,
PerezDelboy A.,
Berghella V.,
Wing D. A.,
Guzman E. R.
Publication year - 2016
Publication title -
ultrasound in obstetrics and gynecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.202
H-Index - 141
eISSN - 1469-0705
pISSN - 0960-7692
DOI - 10.1002/uog.15674
Subject(s) - medicine , odds ratio , ultrasound , gestation , logistic regression , gestational age , cervical cerclage , confidence interval , randomized controlled trial , obstetrics , gynecology , pregnancy , surgery , radiology , biology , genetics
Objective 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 ). Methods 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. Results 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. Conclusions 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.