Pre-cerclage prediction of extreme preterm birth after emergency cervical cerclage in singleton pregnancies: roles of gestational age, cervical dilation, and inflammatory status

Emergency cervical cerclage (ECC) is used in selected singleton pregnancies with cervical insufficiency after cervical dilation has occurred. Pre-cerclage prediction of delivery before 28 weeks remains difficult. This study aimed to develop and internally validate a pre-cerclage prediction model for delivery before 28 weeks after ECC. We retrospectively analyzed 249 women who underwent ECC at two centers between 2016 and 2023. The cohort was divided into a training cohort ( n = 174) and a validation cohort ( n = 75). Univariable and multivariable logistic regression were used to develop a nomogram. Model performance was evaluated using receiver operating characteristic (ROC) analysis, area under the curve (AUC), calibration plots, and decision curve analysis (DCA). Postoperative outcomes were summarized descriptively. The final nomogram included five pre-cerclage variables: pre-pregnancy body mass index (BMI), cervical dilation, prolapsed membranes, pre-cerclage C-reactive protein (CRP) level, and gestational age at cerclage. Receiver operating characteristic analysis showed an area under the curve (AUC) of 0.840 in the training cohort and 0.855 in the validation cohort. Calibration plots showed generally reasonable apparent agreement in the training cohort but indicated some overestimation in the validation cohort. DCA suggested potential net benefit across threshold probabilities of 0.05–0.50. We developed and internally validated a pre-cerclage nomogram for estimating the risk of delivery before 28 weeks after ECC in singleton pregnancies. The model may help support risk stratification before cerclage, but external validation is needed before wider clinical use.