Transvaginal ultrasonography of uterine cervix in prediction of the outcome of labour induction.

ABSTRACT

The aim of this prospective, blind, observational study was to estimate the role of transvaginal ultrasound examination of the uterine cervix in prediction of labour induction outcome in order to adequately chose patients that will have high chance for labour induction. One hundred patients scheduled for induction of labour had a transvaginal ultrasound scan during which cervical length and anterior cervical angle were assessed and the presence/absence of cervical tunneling was noted. Induction was successful if a vaginal delivery within 24 hours took place. The difference between the mean values of the cervical lengths assessed by transvaginal ultrasonography in the group of successful (25.89 mm--SD 8.27, 95% CI 23.65-28.13) and unsuccessful inductions (32.03 mm--SD 6.25, 95% CI 29.01-34.96) is statistically significant (p < 0.05). The anterior cervical angle is not a useful predictor of induction success (sensitivity 22%, positive predictive value 40%). Cervical length assessed by transvaginal ultrasonography is a reliable predictor of labour induction outcome and the best statistical performance of this parameter this test has at the cut-off value of 30 mm (positive predictive value 87.2%, sensitivity 74%, specificity 70%).