Utility of volumetric assessment of cervical funneling to predict cerclage failure.

ABSTRACT

OBJECTIVE: To assess the utility of cervical funnel volume as a predictor of cerclage failure. METHODS: We performed a retrospective cohort study of pregnant women with a McDonald cerclage and sonographic evidence of cervical funneling between 1/2008 and 2/2014. Funnel volume (FV) was calculated and used as a correction factor for cervical length (CL) or cerclage height (CH). Receiver operating characteristic (ROC) curves were used to compare the predictive value of CL, CLFV, CH and CHFV for cerclage failure at <28 or <34 weeks. CLFV was further stratified to the <5th, <10th and >10th percentiles and analyzed for prediction of preterm delivery. RESULTS: Subjects with cerclage failure (n = 30) delivered at a mean gestational age of 29.8 +/- 5.3 weeks compared to 38.1+/- 1.39 weeks in those without failure (n = 27; p < 0.001). ROC curves demonstrated CLFV was the best predictor of delivery <28 weeks (AUC 0.80), while CL was the best predictor of delivery <34 weeks (AUC 0.76). Stratification of CLFV into <5th versus >10th percentile groups was predictive of early preterm delivery (25.1 weeks versus 34 weeks, p = 0.01). CONCLUSIONS: Volumetric assessment of cervical funneling may improve prediction of cerclage failure in the mid-trimester.