Modified Bishop's score and induction of labor in patients with a previous cesarean delivery.
OBJECTIVE
The purpose of this study was to evaluate the association between preinduction modified Bishop's score and obstetric outcome, including successful vaginal birth after prior cesarean (VBAC) and uterine rupture in patients with a previous cesarean undergoing induction of labor.


METHODS
Medical records of all patients who had an induction of labor after a previous cesarean in our institution between 1988 and 2002 were reviewed. Patients were divided into 4 groups according to the modified Bishop's score (0 to 2, 3 to 5, 6 to 8, and 9 to 12). The rates of successful VBAC, symptomatic uterine rupture, and other obstetric outcomes were evaluated in each group. Multivariate regression analyses were performed to adjust for confounding factors.


RESULTS
Out of 685 women included in the study, 187 (27.3%) had a modified Bishop's score <2, 276 (40.3%) of 3 to 5, 189 (27.6%) of 6 to 8, and 33 (4.8%) of 9 to 12. The rate of successful VBAC significantly correlated with the modified Bishop's score (57.5%, 64.5%, 82.5%, and 97.0%, respectively, P < .001). However, the rate of uterine rupture was not statistically significant between the groups (2.1%, 1.8%, 0.5%, 0.0%, P=.48). After adjusting for confounding variables, a modified Bishop's score >/=6 remained associated with successful VBAC (odds ratio [OR] 2.07, 95% CI 1.28-3.35, P < .001).


CONCLUSIONS
The modified Bishop's score before induction of labor is an independent factor associated with successful VBAC.
Bujold
Emmanuel
E
Department of Obstetrics and Gynecology, Hôpital Ste-Justine, Université de Montréal, Montreal, Quebec, Canada. ebujold@med.wayne.edu
Blackwell
Sean C
SC
Hendler
Israel
I
Berman
Susan
S
Sorokin
Yoram
Y
Gauthier
Robert J
RJ
D000328:Adult; D002584:Cervix Uteri / Q000473:pathology*; D005260:Female; D006801:Humans; D007751:Labor, Induced; D008499:Medical Records; D007744:Obstetric Labor Complications / Q000453:epidemiology* / Q000209:etiology; D011247:Pregnancy; D011256:Pregnancy Outcome; D012189:Retrospective Studies; D014219:Trial of Labor; D016064:Vaginal Birth after Cesarean