Obstetric parameters affecting success in a trial of labor: designation of a scoring system.

Abstract

We sought to characterize risk factors in patients undergoing trial of labor after previous cesarean section and to determine whether a subset of patients at high risk of having an unsuccessful trial of labor consequently suffer greater morbidity. A 13-month chart review analyzed 264 labors with documented transverse lower uterine segment scars. Historic and physical examination variables were recorded, and a scoring system was constructed to evaluate successful vaginal delivery after cesarean. Successful vaginal delivery occurred in 192 patients, resulting in a rate of vaginal birth after cesarean of 72.7%. Four variables significantly lower the rate of vaginal birth after cesarean. Of patients scoring 0 (no variables present), 91.5% were successfully delivered vaginally. Scores of 1, 2, and 3 to 4 were associated with the success of vaginal birth after cesarean in 73.9%, 66.7%, and 46.1% of patients, respectively. A score of 3 to 4 did not increase maternal or fetal morbidity in trial-of-labor patients. We constructed a scoring system to evaluate the success of vaginal birth after cesarean. Trial of labor in the subset of patients with the lowest success rate does not increase morbidity.