Prediction of failed labor induction in parous women at term: Role of previous obstetric history, digital examination and sonographic measurement of cervical length

Abstract

To examine the predictive value of previous obstetric history, Bishop score, and sonographic measurement of cervical length for predicting failed induction of labor in parous women at term. This prospective observational study enrolled 110 consecutive parous women at term with singleton gestations scheduled for the induction of labor. Transvaginal ultrasound for measurement of cervical length was performed and the Bishop score was assessed using digital examination. Univariate and multivariate analyses were used for statistical analysis. Labor induction failed in 15 women (14%). In terms of previous obstetric history, women with only previous mid-trimester loss or preterm delivery had a significantly higher risk of failed labor induction than those with at least one previous term delivery. Logistic regression demonstrated that previous obstetric history and the Bishop score, but not cervical length, were found to be significant and independent contributing factors for failed labor induction. In the receiver operating characteristic curves, the best cut-off value of the Bishop score for the prediction of failed labor induction was 3, with a sensitivity of 73% and a specificity of 44%. The previous obstetric history (i.e., only previous mid-trimester loss or preterm delivery) and the Bishop score independently predicted the failure of labor induction in parous women; however sonographic measurement of the cervical length appeared to have a poor predictive value for the risk of failed induction.