[Cervical ultrasonography versus Bishop score as a predictor of vaginal delivery].

PURPOSE

to compare the accuracy of transvaginal ultrasonographic measurement of the uterine cervix with Bishop's score for the prediction of vaginal delivery after labor induction, with 25 mcg of misoprostol.

METHODS

a prospective study for the validation of a diagnostic test was conducted on 126 pregnant women with indication for labor induction. The patients were evaluated by Bishop's score and transvaginal ultrasonography for cervical measurement. They also undergone obstetric transabdominal ultrasound to evaluate static and fetal weight, as well as the amniotic fluid index, and basal cardiotocography for the evaluation of fetal vitality. Labor was induced with vaginal and sublingual misoprostol, one of the tablets containing 25 mcg of the drug and the other only placebo. The tablets were administered every six hours, with a maximum number of eight. Frequency tables were obtained, and measures of central tendency and dispersion were calculated. ROC curves were constructed for the evaluation of Bishop's score and ultrasonographic measurement of the uterine cervix for the prediction of vaginal delivery.

RESULTS

the area under the ROC curve was 0.5 (p=0.8) for the ultrasonographic measurement of the uterine cervix, and 0.6 (p=0.02) for Bishop's score (cut point ≥4). Bishop's score had a sensitivity of 56.2% and specificity of 67.9% for prediction of vaginal delivery, with a positive likelihood ratio of 1.75 and a negative one of 0.65.

CONCLUSIONS

ultrasonographic measurement of the uterine cervix was not a good predictor of evolution to vaginal delivery among patients with misoprostol-induced labor. Bishop's score was a better predictor of vaginal delivery under these circumstances.