Bishop score versus ultrasound of the cervix before induction of labor for prolonged pregnancy: which one is better for prediction of cesarean delivery.

OBJECTIVES

To find an effective way to predict Cesarean section (CS) before induction of labor.

METHODS

Nulliparous women at ≥ 41 weeks of pregnancy were enrolled in the study. Bishop score (BS), cervical length (CL), posterior cervical angle (PCA), quantification of the cervical stromal echogenicity by tissue histograms and opening of the internal cervical os (funnelling) were recorded. The vaginal delivery and CS groups were then compared in terms of the clinical and ultrasonographic cervical findings.

RESULTS

BS, CL, PCA and funnelling were the significant predictors of CS, whereas no such relationship existed for the quantitative echogenicity of the cervical stroma. Although the difference was not statistically significant, the area under the curve was higher for the BS than that for sonographic CL and PCA in the prediction of all CSs. The best cut-off values to predict CS for BS, CL and PCA were <5, >27 mm and <98°, respectively. Combination of all three parameters had a sensitivity of 83.3%, specificity of 100%, positive predictive value of 100% and a negative predictive value of 82% for the prediction of CS.

CONCLUSIONS

In nulliparous women with prolonged pregnancy, the BS predicts the need for CS better than the ultrasonographic assessment of the cervix.