TRANSVAGINAL ULTRASONOGRAPHIC EVALUATION OF THE CERVIX BEFORE LABOR - PRESENCE OF CERVICAL WEDGING IS ASSOCIATED WITH SHORTER DURATION OF INDUCED LABOR

OBJECTIVE: Our purpose was to test the hypothesis that transvaginal ultrasonographically determined characteristics of the cervix are associated with duration of induced labor. STUDY DESIGN: Fifty-three patients scheduled for induction of labor underwent transvaginal ultrasonography, and digital cervical examinations before labor induction. Cox proportional-hazards multiple regression analysis was performed to determine the variables that made a significant contribution to the prediction of latent-phase and total labor duration. In the analysis the possible confounding effects of exogenous prostaglandin, previous vaginal delivery, and previous termination of pregnancy were controlled. RESULTS: Latent-phase and total labor duration were significantly associated with the presence of cervical wedging noted on transvaginal ultrasonography and administration of prostaglandin but not with the result of digital examination of cervical effacement or dilatation. Latent-phase duration was also associated with cervical length measured by transvaginal ultrasonography. The presence of wedging was significantly associated with shorter latent (15.9 +/- 1.7 vs 34.1 +/- 3.8 hours, p = 0.0001) and total (22.0 +/- 1.8 vs 38.3 +/- 3.6 hours, p = 0.0001) labor length. CONCLUSION: The presence of wedging and decreased cervical length observed by transvaginal ultrasonography is associated with a shorter duration of induced labor and may be useful in the evaluation of induction candidates.