Objective:

The aim of this study was to determine what circumstances during transvaginal ultrasound predict vaginal delivery in labour induction of patients with a previous caesarean section. Several studies have confirmed that the accuracy of the Bishop’s score in predicting the outcome of induction of labour is poor, due to the subjectivity of digital examination, which is also influenced by interobserver variability. That is why it is necesary to find an alternative score which provides objectiveness and minimum interobserver differencies.

Materials and methods:

An observational prospective and analytic study was designed and 35 patients were included. All of them had a previous caesarean section and underwent cervical induction with a double balloon device. Transvaginal ultrasound was run in all the cases, regarding cervical length, posterior cervical angle, thickness and cervical dilation. Moreover, data from delivery and postpartum were recorded.

Results:

Vaginal delivery rate was 51.6%. Significative diferencies between cervical lenght in patients who delivered vaginally and those with a second cesarean section were found (26.8mm versus 33.5mm, p = 0.036). No differencies were found between posterior cervical angle measures, nor cervical dilation or cervical thickness.

Conclusions:

Cervical length is outlined as a predictive variable of vaginal delivery in preinduction of patients with a previous cesarean section. It has been demostrated that this measurement is significatively shorter in patients having a vaginal delivery (26.8mm) than in patients with a second cesaren section (33.5 mm).