Diagnostic accuracy of posterior cervical angle and cervical length in the prediction of successful induction of labor

Objective: To determine the accuracy of the posterior cervical angle (PCA) compared with the cervical length and the Bishop score in predicting the outcome of induction of labor (IOL). Methods: The present prospective observational study included IOL candidates who had their PCA and cervical length assessed by transvaginal ultrasonography and the Bishop score at the Obstetrics and Gynecology Department, Kasr El-Aini Hospital, Cairo University, Cairo, Egypt, between April 1 and July 31, 2017. The accuracy of these tests in predicting successful IOL (defined as vaginal delivery) wascompared. Results: The analysis included 49 women with successful IOL and 21 women with unsuccessful IOL. The suggested cutoffs for the prediction of successful IOL were a PCA of more than 99.5 degrees, a cervical length of less than 34mm, and a Bishop score of more than five. The areas under the receiver operating characteristics curves for these three measures were not significantly different. However, a PCA of more than 99.5 degrees had the best sensitivity (91.84%), specificity (90.48), positive predictive value (95.7%), negative predictive value (82.6%), positive likelihood ratio (9.64), and negative likelihood ratio (0.09) compared with the other two predictors. Conclusion: A PCA of more than 99.5 degrees yielded the best accuracy in predicting successful IOL compared with the cervical length and the Bishop score.