The use of sonographic cervical length assessment for the prediction of time from induction to delivery.

OBJECTIVE

The objective of this study is to investigate the role of trans-vaginal cervical length measurement in the prediction of the interval to successful vaginal delivery after induction of labor with balloon catheter.

METHODS

In this prospective study of cervical length measurement before induction of labor, singleton pregnancies that underwent induction of labor between 37 and 42 weeks of gestation were included. The data collected included trans-vaginal sonographic cervical measurements followed by digital cervical assessment. Bishop score was used to quantify digital assessment (before induction of labor).

RESULTS

During the study period, 71 patients were included in the study. A statistically significant linear correlation was found between sonographic cervical length prior to induction of labor and the time of delivery (Pearson correlation 0.335; p values 0.005). Of the 57 vaginal deliveries, 27 patients had a cervical length of less than 28 mm. Patients with a cervical length of less than 28 mm had a significantly shorter time to delivery compared to patients with more than 28 mm length (20.4 versus 28.7, respectively; p value = 0.019). Cervical length of 28 mm remained significantly correlated even after performing several logistic regression models in order to control for confounders such as parity and age. In addition, a correlation was found between Bishop scores of above 7 to the time to delivery.

CONCLUSIONS

Cervical length is correlated linearly to the time interval between induction of labor and delivery. A cervical length of less than 28 mm was found to be statistically significant in predicting a shorter time to delivery.