Comparison of the predictive value of digital examination (Bishop’s score) and ultrasound evaluation for labor induction success

Abstract

Abstract Aim: Cervical ripening is the main factor of success in the induction of labor. The aim of the study was to compare predictive value of digital examination (Bishop’s score) and ultrasound evaluation for labor induction success. Material and methods: The study was carried out in the Fetal Medicine Department of Medical University of Lodz between 2006-2009. 101 pregnant women comprised the study group. Results: Comparing the subgroups with successful and unsuccessful labor induction, the main differences were observed in the entire Bishop’s score (7.21 versus 5.4 points; p<0.001). Ultrasound measurements demonstrated significant differences in the cervical diameter (55.5 vs. 51.6mm; p<0.01) and internal os (8.64 vs. 3.28mm; p<0.001). We noticed a significant correlation between the outcome of the labor induction and the shape of the canal (p<0.001), as well as the posterior cervical angle (p<0.001). Ultrasound measurements of the internal os width (p<0.001; cut-off point: 4.5mm), the length (p<0.001; cut-off point: 23.5mm) and shape of the cervical canal (p<0.001; Y shape in 36.21%), were significant independent factors in the prediction of labor induction. Following the Bishop’s score model, we created a similar score for the ultrasound measurements (total -10 points). The entire score of the ultrasound measurements with the cut-off value: 4.5 points, was found to be a significant factor (p<0.001) predicting the success of labor induction. Conclusion: The ultrasound evaluation of the cervix demonstrates significantly better predictive value in the prognosis of labor induction comparing to the Bishop’s score.