A novel method for assessing the condition of the cervix before labor induction: Cervical length/thickness ratio

Abstract

Background/Aim: Due to the increasing cesarean rates globally, new methods for supporting vaginal delivery and induction of successful vaginal delivery are still being developed. We aimed to obtain an easy-to-use method that can predict the effectiveness of cervical ripening agents before labor induction. So, we presented the effects on labor by measuring the thickness of the cervix and the cervical length/thickness ratio ultrasonographically. Methods: In this prospective cohort study, we evaluated 183 pregnant between 37 and 41 weeks of gestational age and will apply vaginal delivery induction. Before oxytocin induction, we applied 10 mg dinoprostone vaginally to women whose cervix was stiff. We started labor induction with oxytocin when regular uterine contractions or dilatation occurred. We used the Bishop Scoring System for favorable cervix defining. Then, we compared the groups with successful and unsuccessful cervical ripening regarding cervical length and thickness parameters. Results: The mean cervical thickness of the pregnant women with successful cervical ripening was 34.5 (7.5) mm before treatment, while the mean values of the unsuccessful group were 29.2 (9.1) mm (P < 0.001). The cervical length did not differ between the two groups (31.6 [8.2] vs. 32.5 [6.8], P = 0.44), while the cervical length/thickness ratio was lower in the group with successful ripening (0.9 [0.38–2], P < 0.001). Cervical length/thickness ratio was the highest predictor of the favorable cervix with dinoprostone. Each 1 unit decrease in the length/thickness ratio of the cervix increases the preparation of the cervix for induction by 0.25 times (P = 0.04). A successful response to dinoprostone can be obtained if the cervical length/thickness ratio is <1.06 mm (P < 0.001). Conclusion: In conclusion, assessing the cervix’s condition before labor induction by measuring the cervical length/thickness ratio may be a good predictor of cervical ripening activity.