CHIEF EDITOR’S NOTE: This article is part of a series of continuing education activities in this Journal through which a total
of 36 AMA/PRA Category 1 CreditsTMcan be earned in 2008. Instructions for how CME credits can be earned appear on the
last page of the Table of Contents.
Predicting Success and Reducing the
Risks When Attempting Vaginal Birth
Lorie M. Harper, MD,* and George A. Macones, MD, MSCE†
*Resident Physician, and †Mitchell and Elaine Yanow Professor and Chair, Department of Obstetrics and
Gynecology, Washington University in St. Louis, St. Louis, Missouri
The goal of this manuscript is to review the contemporary evidence on issues pertinent to improving
the safety profile of vaginal birth after cesarean (VBAC) attempts. Patients attempting VBAC have
success rates of 60%–80%, and no reliable method of predicting VBAC failure for individual patients
exists. The rate of uterine rupture in all patients ranges from 0.7% to 0.98%, but the rate of uterine
rupture decreases in patients with a prior vaginal delivery. In fact, in patients with a prior vaginal
delivery, VBAC appears to be safer from the maternal standpoint than repeat cesarean. Inevitably, the
obstetrician today will encounter the situation of deciding whether or not to induce a patient with a
uterine scar, and particular attention is paid to the success and risks of inducing labor in this patient
population. Induction of labor is associated with a slightly lower successful vaginal delivery rate,
although the rate remains above 50% in virtually all patient populations. The rate of uterine rupture
increases slightly, but still remains around 2%–3%. Although misoprostol use is discouraged due to its
association with increased risks of uterine rupture, transcervical catheters, oxytocin, and amniotomy
may be used to induce labor in women attempting VBAC.
Target Audience: Obstetricians & Gynecologists, Family Physicians
Learning Objectives: After completion of this article, the reader should be able to summarize recent
literature regarding vaginal birth after cesarean and list factors related to labor induction success among
women with a history of cesarean delivery.
The rate of cesarean delivery in the United States
continues to rise, reaching a rate of 30.3% in 2005,
driven in part by a decrease in the rate of vaginal
birth after cesarean (VBAC) (1). In that year, approx-
imately 90% of women with a prior cesarean delivery
underwent a repeat cesarean, although data are un-
available regarding the number of repeat cesareans
due to failed VBAC attempts. The low rate of VBAC
is largely due to concerns over immediate maternal and
neonatal complications, including uterine rupture, hys-
terectomy, and perinatal morbidity and mortality. This
potential increase in short-term morbidity must be bal-
anced by the increase in maternal and neonatal risk
associated with multiple repeat cesarean deliveries (2).
As the rate of cesarean deliveries rose, so did the
rate of induction of labor, which doubled between
Dr. Macones has disclosed that he was the recipient of grant
research support from the National Institute of Child Health and
Human Developement (NICHD). All other authors have dis-
closed that they have no financial relationships with or interests
in any commercial companies pertaining to this educational
The Faculty and Staff in a position to control the content of this
CME activity have disclosed that they have no financial relation-
ships with, or financial interests in, any comercial companies
pertaining to this educational activity.
Lippincott Continuing Medical Education Institute, Inc. has
identified and resolved all faculty conflicts of interest regarding
this educational activity.
Reprint requests to: Lorie M. Harper, Washington University in
St. Louis, 4566 Scott Avenue, Campus Box 8064, St. Louis, MO
63110. E-mail: email@example.com.
Volume 63, Number 8
OBSTETRICAL AND GYNECOLOGICAL SURVEY
Copyright © 2008
by Lippincott Williams & Wilkins
ciated with the use of misoprostol in the gravid patient with a
previous cesarean section. Am J Obstet Gynecol 1999;180:
17. Blanchette; HA, Nayak S, Erasmus S. Comparison of the
safety and efficacy of intravaginal misoprostol (prostaglandin
E1) with those of dinoprostone (prostaglandin E2) for cervical
ripening and induction of labor in a community hospital. Am J
Obstet Gynecol 1998;180:1551–1556.
18. Wing DA, Lovett K, Paul RH. Disruption of prior uterine inci-
sion following misoprostol for labor induction in women
with previous cesarean delivery. Obstet Gynecol 1998;91:
19. Nwachuku V, Sison A, Quashie C, et al. Safety of misoprostol
as a cervical ripening agent in vaginal birth after cesarean
section. Primary Care Update Ob/Gyns 2001;8:244–247.
20. Lin C, Raynor D. Risk of uterine rupture in labor induction of
patients with prior cesarean section: an inner city hospital
experience. Am J Obstet Gynecol 2004;190:1476–1478.
21. ACOG Committee Opinion No 342, August 2006. Induction of
Labor for Vaginal Birth After Cesarean Delivery.
22. ACOG Practice Bulletin No 10, November 1999. Induction of
23. Ravasia DJ, Wood SL, Pollard JK. Uterine rupture during
induced trial of labor among women with previous cesarean
delivery. Am J Obstet Gynecol 2000;183:1176–1179.
24. Yogev Y, Ben-Haroush A, Lahav E, et al. Induction of labor
with prostaglandin E2in women with previous cesarean sec-
tion and unfavorable cervix. Eur J Obstet Gynecol Reprod Biol
25. Gelber S, Sciscione A. Mechanical methods of cervical ripening
and labor induction. Clin Obstet Gynecol 2006;49:642–657.
26. Bujold E, Blackwell SC, Gauthier RJ. Cervical ripening with
transcervical Foley catheter and the risk of uterine rupture.
Obstet Gynecol 2004;103:18–23.
27. Hoffman MK, Sciscione A, Srinivasana M, et al. Uterine rup-
ture in patients with a prior cesarean delivery: the impact of
cervical ripening. Am J Perinatol 2004;21:217–222.
28. Goetzl L, Shipp TD, Cohen A, et al. Oxytocin dose and the risk
of uterine rupture in trial of labor after cesarean. Obstet
29. Cahill AG, Stamilio DM, Odibo AO, et al. Does a maximum
dose of oxytocin affect risk for uterine rupture in candidates
for vaginal birth after cesarean delivery? Am J Obstet Gynecol
Predicting and Improving the Safety of VBAC Attempts Y CME Review Article545