Predictors of cerclage failure in patients with singleton pregnancy undergoing prophylactic cervical cerclage

The role of cervical cerclage to prevent preterm birth (PTB) remains controversial. The aim of this study was to identify prognostic factors for cerclage failure among singleton pregnant women following prophylactic cerclage (PC). A retrospective analysis of PC was performed in a single center. The main outcome measure was cerclage failure, defined by spontaneous early PTB prior to 32 weeks' gestation. Age, BMI, history of instrumentation of the uterus, history of second trimester miscarriage, previous conization, positive vaginal swab prior cerclage, gestational age at time of cerclage, CRP 1 week after cerclage and post-cerclage US changes of cervical length were tested as predictive factors. Descriptive statistical and binary logistic regression analyses were performed. 141 women underwent cerclage procedures between 2007 and 2016. 39 patients had PC with McDonald suture, singleton pregnancy and complete clinical follow-up information, thus fulfilling the inclusion criteria. Multivariate analysis showed that history of instrumentation of the uterus was the only independent prognostic factor [OR = 0.14 (0.03, 0.72) p = 0.019] for cerclage failure. This is the first study showing that a history of previous uterine instrumentation is an independent predictor of cerclage failure. This finding has significant clinical implications for women of childbearing age, particularly when management of miscarriage/abortion is being considered. Women should be informed about the potential risks when counseled prior to surgical evacuation and medical management or cervical ripening should be considered. These results are also helpful in counseling patients undergoing cerclage, when a prior uterine instrumentation has been performed.