The significance of ultrasound parameters and clinical factors in predicting successful labor induction among nulliparous women.

Abstract

Objectives: To compare the values of ultrasound and clinical parameters for predicting outcomes of induction of labor (IOL) among healthy nulliparous women with a singleton, term cephalic pregnancy.

Methods: The cervical length, cervical strain elastography, posterior cervical angle, head-perineum distance, Bishop score, and maternal parameters were assessed before IOL with a combined method-Foley catheter and Misoprostol perorally. The main outcome was vaginal delivery.

Results: Variation in cervical tissue elasticity, represented by elasticity index (E), was significantly different between outcome groups-vaginal delivery and cesarean section (CS) in internal os, in the anterior lip near the cervical canal and the midpoint of the anterior and posterior lip (p < 0.05). The E was higher-softer in the vaginal delivery group. The overall elasticity was significantly higher in the middle part of the cervix in the vaginal delivery group. However, other ultrasound metrics did not differ significantly across the outcome groups. Overall, women who delivered vaginally were taller and had a lower pre-pregnancy BMI (p = 0.02 for both variables). Univariate and multivariate analyses showed maternal height was the significant independent predictor of CS (AOR 0.91, 95% CI 0.84-0.98). The prognostic value for vaginal delivery, based on cervical length, maternal height, Bishop score, and parameters of cervical strain elastography, was poor (AUC < 0.7).

Conclusion: The study underscores the importance of cervical tissue elasticity in predicting vaginal delivery outcomes, while also highlighting that maternal height is a significant independent predictor of cesarean delivery. However, evaluated metrics in the study have limited prognostic value for predicting vaginal delivery. This suggests a need for further research to identify more reliable predictors of delivery outcomes.