Comparison of sonographic score and Bishop score in the prediction of successful labor induction in term patients: A prospective observational study

Background

The cervical favorability for IOL is assessed by scoring systems. There are various scoring systems, including the Field system, Lange pelvic scoring system, and Bishop scoring system, which was then modified and termed ‘The modified Bishop scoring system, and it is the most widely used one. This scoring is done based on the assessment of the station of the fetal presenting part, consistency, position, dilatation, and length of the maternal cervix. Owing to its subjective assessment, there is a high chance of inter-observer variability. Therefore, radiological methods such as Trans-vaginal ultrasonogram (TVS) and Trans-abdominal ultrasonogram (TAS) are preferred over manual methods. This study aims to determine the role of assessment of the cervix by Modified Bishop Score and assessment of the cervical parameters by Transvaginal ultrasonogram (TVS) and compare them in predicting the outcome of labour.

Material and methods

This prospective observational study was conducted by the Department of Obstetrics and Gynecology in a tertiary care hospital located at Chengalpattu, Tamil Nadu, in a term singleton pregnancy woman, and the Study period was from January 2023 to July 2023 for six months. In total, one hundred fifty pregnant women were recruited. The study inclusion criteria were singleton pregnant women with intact amniotic membranes and a period of gestation >37 weeks with cephalic presentation. The findings of TVS were blinded to the person who measured cervical parameters for the bishop score. IOL done for both favorable and unfavorable cervix according to the guidelines given by FOGSI-ICOG (2018) for IOL.

Results

Receiver operating characteristic (ROC) curve analysis showed the area under the curve (AUC) for the TVS score was 0.705(95 % CI: 0.616–0.794) against the standard bishop score. TVS Score≥6.5 cm is the best cut-off value to ascertain successful IOL with a sensitivity of 99 % and specificity of 94 % among singleton pregnancy women.

Conclusion

This prospective observational study deduced that TVS scoring is a valid alternative tool against the standard bishop score in predicting cervical favorability for IOL among singleton pregnant women with plausible sensitivity and specificity. TVS scoring for assessing cervical favorability acts as an outstanding marker in predicting the IOL with a cut-off value of ≥6.5 cm in singleton pregnant women.