Vaginal birth after cesarean delivery: a group practice's approach to minimizing failed trial of labor

Objective: Among women attempting a trial of labor (TOL) after a prior abdominal delivery, 60-80% accomplish a vaginal birth after cesarean (VBAC). McMahon and coworkers (N Engl J Med, 1996) have indicated that at a 60% success level for TOL, the remaining 40% incurred enough major complications that the scheduled repeat cesarean section group was less morbid overall. The same authors speculated that a success rate of 80% might be necessary for the TOL group's morbidity to be superior. We sought to review our group's patient selection experience during an interval when successful TOL consistently exceeded 80%.Methods: The study interval ranged from January 1995 through June 1997 and was limited to patients with one previous low transverse cesarean section. Rather than using administrative or charge-related diagnoses, we analyzed a departmental database that included each delivering physician's selection of one of four VBAC categories: successful VBAC, unsuccessful VBAC, patient declined trial of labor, or physician advised against trial of labor. All deliveries were at a single institution and were performed by one of seven obstetricians in a group practice.Results: During the study interval, 332 women provided a history of a single previous cesarean delivery. Of these 332, a total of 173 attempted a TOL and 150 of the 173 (87%) were successful. Fifty-eight of the 332 (18%) declined a trial of labor despite being assessed as excellent candidates, and 101 (30%) were advised against a TOL by their physician. Most common reasons for physicians discouraging labor included malpresentation, fetal macrosomia, and clinically small pelvis. Complications for the 23 of 173 (13%) experiencing a failed TOL included 1 asymptomatic partial separation of a uterine scar and 4 cases of puerperal fever; neither transfusion nor hysterectomy was required.Conclusions: This study demonstrates that in a population of women with one prior cesarean delivery, it is possible for a group practice to achieve a TOL success rate exceeding 80%. In our opinion the managing physician selecting out those patients least likely to attain a successful TOL contributes to a low failed TOL rate. We speculate that an analysis for best practice patterns within our group might reveal information of value for future practice guidelines.