Clinical Study

Does cervical length measurement help to predict the success rate of labor induction using misoprostol at term in women with strictly unfavorable cervix?

  • Eray Çaliskan
  • Emek Doger
  • Yigit Çakiroglu
  • Sabiha Özkan
  • Semih Özeren
  • Aydin Çorakçi

Received Date: 14.10.2005 Accepted Date: 07.02.2006 J Turk Ger Gynecol Assoc 2006;7(3):184-188

OBJECTIVES

To evaluate the clinical value of transvaginal ultrasonographic cervical length measurement for prediction of successful labor induction at term in women with strictly unfavorable cervices.

MATERIALS-METHODS

Seventy-four women at term with maternal and fetal indications for labor induction were included in the study. All women had singleton pregnancies in vertex presentation and Bishop score <=4 in the presence of closed cervices without evidence of uterine contractions. Fifty μcg sublingual misoprostol every four hours to a maximum six doses was commenced. Cervical length was measured via transvaginal ultrasound, receiver operator curve characteristics were analyzed for prediction of cesarean delivery rate and failed induction, which was defined as cases undelivered within 24 hours or inability to induce uterine contractions.

RESULTS

Fourteen cesarean deliveries (%18.9) and seven induction failures (%9.4) were diagnosed. Using the optimum cut-off value of 30 mm as a threshold of cervical length for the prediction of induction failure, a sensitivity of 85.7%, a specificity of 44.3%, a positive predictive value of 15% and a negative predictive value of 96.4% were obtained. Using the optimum cut-off value of 30 mm as a threshold of cervical length for the prediction of cesarean delivery, a sensitivity of 85.7%, a specificity of 43.3%, a positive predictive value of 26% and a negative predictive value of 92.9% were obtained. The cesarean section rate was 26.1% for the women who had a cervical length >30 mm, while it was 7.1% for the women with a cervical length <30 mm (p=0.04). Fetal birth weight was a better predictor of failed induction (Area Under the Curve (AUC): 0.65) followed by cervical length (AUC: 0.63).

CONCLUSIONS

Although cervical length measurement has some predictive value, AUC analysis revealed that it is far from being an ideal test for detecting induction failures. 30mm can be a good clinical cut-off value to predict cesarean deliveries in women with misoprostol induced labor.

Keywords: Induced labor, Ultrasonography, Cervix uteri, Treatment failure, Cesarean sections