Role of ultrasound parameters in the prediction of failure of induction of labor using Dinoprostone.

UNLABELLED: Introductio-Aim: Labor induction is the artificial induction of uterine contractions in a woman who was not already in labor in order to achieve a vaginal birth. The main objective of our study was to analyze the role of ultrasound parameters in the prediction of failure of induction of labor.

METHODS

This was a prospective observational study performed in a tertiary care maternity. For all the women who met our inclusion criteria, we measured these ultrasound parameters: Cervical length (CL), cervical dilation, cervical posterior angle (CPA), fetal head-perineum distance (FHPD), fetal occiput position, biparietal diameter (BPD) and estimated fetal weight (EFW). We defined failure of induction of labor as the occurrence of a cesarean section at any moment after the start of the induction.

RESULTS

we collected 150 cases of induction of labor that met our inclusion criteria. Failure of induction rate was 45 %. Ultrasound parameters that were significantly associated to failure of induction were Cervical length (p=0.003), cervical dilation (p=0.002), cervical posterior angle (p<10-3), fetal head-perineum distance (p<10-3) and estimated fetal weight (p=0.006). Multivariate regression analysis found that posterior cervical angle and fetal head-perineum distance were the variables independently affecting the outcome of the induction of labor with respective thresholds of 105° and 55mm.

CONCLUSION

Ultrasound can be very useful in predicting the failure of labor induction. The threshold values that we found should be tested and validated in future studies to create a model to predict failure of labor.