A comparative study between modified Bishop score and transvaginal sonography to predict successful induction of labor

Abstract

Background Modified Bishop score (MBS) and cervical length determination by transvaginal sonography (TVS) are the two methods for predicting successful vaginal delivery based on pre-induction favourability of the cervix. Aims and Objectives This study compared both methods for predicting successful vaginal delivery. The primary objective was to compare the predictive value of MBS and TVS in predicting successful induction of labor. The secondary objective was to obtain the cut-off score of MBS and TVS for successful induction of labor. Methods A prospective study was done involving 100 pregnant women admitted for induction of labor. TVS was done to measure the cervical length before induction of labor. MBS was also calculated for all the patients. Labor was induced with prostaglandins. Labor induction was considered successful if there was an onset of uterine contractions and cervical dilatation within 24 h of induction. Results For successful induction of labor, the cutoff of cervical length by TVS and MBS was 2.5 cm and 6, respectively. Cervical length assessment by TVS performed better than the MBS (sensitivity 61.8% vs. 28.9%, Specificity 95.8% vs. 100%). Conclusion MBS and cervical length measurement by sonography both are good predictors of successful induction of labor. Cervical length measurement by TVS provides a better prediction of the likelihood of vaginal delivery.

Keywords

• induction of labor
• modified bishop score
• negative predictive value
• positive predictive value
• prediction of labor
• sensitivity
• specificity
• transcervical length