Iranian Society of Gynecology Oncology


1 Associate Professor, Department of Obstetrics and Gynecology, Vali-Asr Hospital, Tehran University of Medical Sciences, Tehran, IR Iran

2 Assistant Professor, Department of Obstetrics and Gynecology, Vali-Asr Hospital, Tehran University of Medical Sciences, Tehran, IR Iran

3 Tehran University of Medical Sciences, Tehran, IR Iran

4 Department of Obstetrics and Gynecology, Vali-Asr Hospital, Tehran University of Medical Sciences, Tehran, IR Iran

5 Pediatrician, Tehran University of Medical Sciences, Tehran, IR Iran


Objectives: Determining the necessity of cesarean section (C/S) due to failure of induction of labor (IOL) is essential to avoid fetus distress. In this study, the performance of the Bishop score and trans-vaginal ultrasound measurements were compared to predict successful IOL, and the most useful cut-off points were estimated.
Methods: Nulliparous women with gestation age of > 37 weeks with a live fetus in cephalic presentation were invited to participate in this study. Bishop score was assessed by digital examination, and trans-vaginal ultrasound was used to measure cervical length. Trans-abdominal ultrasound was utilized to determine the fetal head position.
Results: One hundred women entered the study. Multiple regression analysis revealed that the Bishop score and cervical length had a reliable predictive value in determining successful IOL. The cut-off points for predicting successful induction were 16 mm for cervical length and 5 for the Bishop score, using receiver operating characteristic curves (ROC). Both cervical length and Bishop score were good predictors for vaginal delivery (sensitivity and specificity of 85% and 67%, respectively for cervical length; and 84% and 70%, respectively for Bishop score).
Conclusions: Cervical length is a good predictor of successful IOL. Considering the painful process of digital exam, implementing trans-vaginal ultrasound is preferred.


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