Use of fetal-pelvic index in the prediction of vaginal birth following previous cesarean section.

AIM

To clarify the usefulness of the fetal-pelvic index as a predictor of vaginal birth after previous lower segment cesarean section.

METHODS

One hundred and seventy women with one lower segment cesarean section who attempted for trial of vaginal birth were enrolled. Pelvimetry was performed to measure maternal pelvic inlet and mid-cavity circumferences at 37 weeks gestation. Ultrasound was performed to measure fetal head and abdominal circumferences at 38-39 weeks. The fetal-pelvic index was derived. The predictability of fetal-pelvic index in the predicting the outcome of delivery was calculated.

RESULTS

Fifty-seven (33.5%) women required repeated cesarean section and 113 (66.5%) delivered vaginally. Twenty-two women with positive fetal-pelvic index had repeated cesarean section. The predictability of positive fetal-pelvic index was 48.9%. Ninety of the 125 patients with a negative fetal-pelvic index delivered vaginally. The predictability of negative fetal-pelvic index was 72.0%.

CONCLUSIONS

Fetal-pelvic index derived in the antenatal period has low predictive value in predicting of successful vaginal birth after cesarean section. This index is not useful in clinical practice.