Bishop score: A poor diagnostic test to predict failed induction versus vaginal delivery

Background. We evaluated the accuracy of the Bishop score in predicting the likelihood of successful labor induction (entry into active phase) in null iparous and multiparous women. Methods. During an index year, all patients having induction of labor and a preinduction Bishop score were included in a standard protocol for cervica l ripening and use of oxytocin. Receiver-operating characteristic (ROC) cur ves were constructed for Bishop scores (0 to 11) to predict abdominal deliv ery for failed induction (final cervical dilation <4 cm) versus vaginal del ivery. Results. Parturients who had vaginal delivery (n = 253) and those in whom a ttempted induction failed (n = 38) did not differ significantly with respec t to maternal demographics, length of gestation, Bishop score and its distr ibution, and infant birth weight. The area under the ROC curve did not diff er significantly from the area under the nondiagnostic line. Conclusion. The Bishop score appears to be a poor predictor of the outcome of labor induction.