Failed vaginal birth after a cesarean section: How risky is it? I. Maternal morbidity

OBJECTIVE: Our purpose was to determine the maternal risks associated with failed attempt at vaginal birth after cesarean compared with elective repea t cesarean delivery or successful vaginal birth after cesarean. STUDY DESIGN: From 1989 to 1998 all patients attempting Vaginal birth after cesarean and all patients undergoing repeat cesarean deliveries were revie wed. Data were extracted from a computerized obstetric database and from me dical charts. The following three groups were defined. women who had succes sful vaginal birth after cesarean, women who had failed vaginal birth after cesarean, and women who underwent elective repeat cesarean. Criteria for t he elective repeat cesarean group included no more than two previous low tr ansverse or vertical incisions, fetus in cephalic or breech presentation, n o previous uterine surgery, no active herpes, and adequate pelvis. Predicto r variables included age, parity, type and number of previous incisions, re asons for repeat cesarean delivery, gestational age, and infant weight. Out come variables included uterine rupture or dehiscence, hemorrhage > 1000 mi , hemorrhage > 2000 mi, need for transfusion, chorioamnionitis, endometriti s, and length of hospital stay. The Student t test and the chi (2) test wer e used to compare categoric variables and means; maternal complications and factors associated with successful vaginal birth after cesarean were analy zed with multivariate logistic regression, allowing odds ratios, adjusted o dds ratios, 95% confidence intervals, and P values to be calculated. RESULTS: A total of 29,255 patients were delivered during the study period, with 2450 having previously had cesarean delivery. Repeat cesarean deliver ies were performed in 1461 women (5.0%), and 989 successful vaginal births after cesarean delivery occurred (3.4%). Charts were reviewed for 97.6% of all women who underwent repeat cesarean delivery and for 93% of all women w ho had vaginal birth after cesarean; Vaginal birth after cesarean was attem pted by 1344 patients or 75% of all appropriate candidates. Vaginal birth a fter cesarean was successful in 921 women (69%) and unsuccessful in 424 wom en. Four hundred fifty-one patients undergoing cesarean delivery were deeme d appropriate for vaginal birth after cesarean. Multiple gestations were ex cluded from analysis. Final groups included 431 repeat cesarean deliveries and 1324 attempted vaginal births after cesarean; in the latter group 908 w ere successful and 416 failed. The overall rate of uterine disruption was 1 .1% of all women attempting labor; the rate of true rupture was 0.8%; and t he rate of hysterectomy was 0.5%. Blood loss was lower (odds ratio, 0.5%; 9 5% confidence interval, 0.3-0.9) and chorioamnionitis was higher (odds rati o, 3.8%; 95% confidence interval, 2.3-6.4) in women who attempted vaginal b irths after cesarean. Compared with women who had successful Vaginal births after cesarean, women who experienced failed vaginal births after cesarean had a rate of uterine rupture that was 8.9% (95% confidence interval, 1.9- 42) higher, a rate of transfusion that was 3.9% (95%, confidence interval, 1.1-13.3) higher, a rate of chorioamnionitis that was 1.5% (95% confidence interval, 1.1-2.1) higher, and a rate of endometritis that was 6.4% (95% co nfidence interval, 4.1-9.8) higher. CONCLUSION: Patients who experience failed vaginal birth after cesarean hav e higher risks of uterine disruption and infectious morbidity compared with patients who have successful vaginal birth after cesarean or elective repe at cesarean delivery. Because actual numbers of morbid events are small, ca ution should be exercised in interpreting results and counseling patients. More accurate prediction for safe, successful vaginal birth after cesarean delivery is needed.