Bishop score and transvaginal ultrasound for preinduction cervical assessment: a randomized clinical trial
Keywords:
Bishop score, Induction of labor, Prostaglandin, Transvaginal ultrasonography, Cervical wedgingAbstract
Background: The objective was to compare transvaginal ultrasound with the Bishop score for preinduction cervical assessment and for choice of induction agent.
Methods: 150 women were randomized to have preinduction cervical assessment for choice of induction agent based on either Bishop score or transvaginal ultrasound. The primary outcome measure was the percentage of women who were administered prostaglandin as a preinduction agent. The criteria for considering the cervix as unripe and thus for using prostaglandin were either a Bishop score <6 or cervical wedging of <30% of the total cervical length. Secondary outcome measures included interval to active phase, interval to delivery and rate of Caesarean section and fetal outcome.
Results: While 85% of women received prostaglandin in the Bishop score group, only 53% of them did in the transvaginal ultrasound group (p =0.001). The interval to active phase, interval to delivery, rate of Caesarean section for failed induction and fetal outcomes were similar in both groups.
Conclusions: With the suggested cut-off values of a Bishop score <6 and wedging <30%, the use of transvaginal ultrasound instead of Bishop score for preinduction cervical assessment to choose induction agent significantly reduces the need for intracervical prostaglandin treatment without adversely affecting the success of induction.
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