Sonographic cervical assessment to predict the success of labor induction: a systematic review with metaanalysis

Objective

The purpose of this investigation was to review the literature that evaluates sonographic cervical assessment to predict successful induction of labor.

Study Design

Published prospective trials that measured sonographic cervical length before labor induction was initiated were evaluated. Trials were excluded if they contained data presented in later articles or did not contain extractable data. The total analysis included 20 trials with 3101 aggregate participants.

Results

Cervical length predicted successful induction (likelihood ratio of positive test, 1.66; 95% confidence interval [CI], 1.20-2.31) and failed induction (likelihood ratio of negative test, 0.51; 95% CI, 0.39-0.67). Cervical length did not predict any specific outcome (eg, mode of delivery). The assessment of cervical wedging proved to be a useful diagnostic test, with a likelihood ratio of a positive test result of 2.64 and a likelihood ratio of a negative test result of 0.64.

Conclusion

Sonographic cervical length was not an effective predictor of successful labor induction. Further evaluation of cervical wedging in the prediction of labor induction appears warranted.

Key words: cervical length, cervical wedging, diagnostic accuracy, induced labor, ultrasound scan