Preinduction cervical assessment by Bishop's score and transvaginal ultrasound

In this pilot study, 50 patients underwent preinduction cervical assessment by digital Bishop Score (BS) and transvaginal ultrasonography. The BS was lower in 7 patients requiring caesarean section than in 43 delivered vaginally (P = 0.017). Of seven ultrasound parameters examined, six (cervical length, width, dilatation, application and position and lower segment thickness) were similar in both groups. Cervical angle, however, was more acute in those delivered abdominally than vaginally (median = 60 degrees and 90 degrees, respectively, P = 0.002). Posterior cervical angle was more accurate than BS in predicting vaginal delivery (Kappa = 0.48 versus 0.21). Patient discomfort was significantly less with transvaginal ultrasound than digital examination. Combining posterior cervical angle greater than 70 degrees and BS greater than 5 yielded the best accuracy in predicting successful induction of labour (sensitivity = 88%, specificity = 100%, Kappa = 0.68).