Predictors of efficacy for cervical ripening among the Bishop score criteria in nulliparous women at term.

OBJECTIVE

To determine predictors of efficacy for cervical ripening among the Bishop score criteria in nulliparous women at term.

METHOD: Prospective observational study of nulliparous women with singleton term fetuses in vertex presentation, intact membranes, and an unfavorable cervix (Bishop score < 6) who underwent cervical ripening with a cervical-ripening balloon (CRB; n = 47) or dinoprostone vaginal insert (PG; n = 28). The authors analyzed Bishop score criteria (dilatation, effacement, fetal station, consistency, position) before and after device removal. Primary outcome was favorable cervix (Bishop score ≥ 6) after device removal. Secondary outcomes were vaginal delivery, modification of Bishop score criteria, and perinatal morbidity.

RESULTS

Rates of favorable cervix after cervical ripening were similar between groups (66.7% with CRB vs. 59.3% with PG; P = 0.526). Vaginal delivery (76.6% vs. 78.6%; P = 0.843) and perinatal morbidity did not differ between groups. CRB appeared to be more effective than PG in increasing consistency (+0.7 ± 0.2 vs. +0.3 ± 0.2; P = 0.001) and dilatation of the cervix (+1.3 ± 0.3 vs. +0.9 ± 0.3; P = 0.005). No Bishop score criterion was found as a significant predictor for vaginal delivery.

CONCLUSION

CRB seems to be more effective than PG in increasing the consistency and dilatation of the cervix. Efficacy of CRB and PG for vaginal delivery was similar.