Three-dimensional power Doppler ultrasound assessment of the cervix for the prediction of successful induction of labor with prostaglandin in prolonged pregnancy.

OBJECTIVE

The purpose of this study was to determine whether 3-dimensional (3D) power Doppler ultrasound examination of the cervix can predict the success of labor induction with prostaglandin in prolonged pregnancy.

METHODS

A prospective study was conducted with 36 women undergoing labor induction with prostaglandin at 41 gestational weeks 5 days and later. All 36 women underwent a transvaginal 2-dimensional gray scale ultrasound examination and a 3D power Doppler ultrasound examination of the cervix immediately before a planned post-term checkup. The analyzed variables were length, anterior-posterior diameter, and width of the cervix and any cervical funneling, cervical volume (in cubic centimeters), vascularization index, flow index, vascularization flow index, parity, and Bishop score. Results were compared among women with start of labor at 12 hours or less and more than 12 hours after application of the first prostaglandin suppository and among women who had delivery at 24 hours or less and more than 24 hours after the start of induction.

RESULTS

Sonographically measured cervical length was shorter (mean, 1.8 versus 2.4 cm; P = .04), the Bishop score was higher (median, 5 versus 3; P = .02), and more women were parous (70% versus 37%; P = .05) among women who were in labor within 12 hours than in those who were not. The Bishop score was higher (median, 4 versus 2; P = .03) and more women were parous (69% versus 23%; P = .01) among women who had delivery at 24 hours or less than among those who did not. Cervical volume and the results of the 3D power Doppler ultrasound examination did not differ among women with different outcomes of labor induction.

CONCLUSIONS

In women undergoing induction of labor with prostaglandin at 41 gestational weeks 5 days or later, sonographic cervical length, Bishop score, and parity are related to the success of labor induction, whereas cervical volume and the results of the 3D power Doppler examination are not.