Linking
Evidence and Experience
Vaginal Birth After Cesarean Delivery
Current Status
JAMA Vol.
287 No. 20, May 22/29, 2002
The dictum "Once a cesarean, always a
cesarean" ruled for most of the 20th century.1 Nevertheless, in the
1970s a small group of women who had prior cesarean deliveries were eager to
experience vaginal birth and risked a trial of labor (a purposeful attempt to
permit active labor development with progression to vaginal delivery).2 Success in such cases
led the National Institutes of Health in 1981 to promote trial of labor for
patients who had previous cesarean deliveries.2
In 1981, the US rate of successful vaginal birth
after a prior cesarean delivery (VBAC) was only 3%, with the overall cesarean
delivery rate of 17.9%. By 1997, the incidence of VBAC rose steadily to 27.4%.
Despite this dramatic increase in VBACs, the total US cesarean delivery rate
rose to only 20.8% during the same time period (Figure 1).3, 4 The American College
of Obstetricians and Gynecologists (ACOG) stressed in 19845 and 19956 that VBAC should be
offered as an option to patients with fetuses in vertex presentations, with 1
or more low transverse uterine scars, and no known contraindication for vaginal
delivery. Informed consent for trial of labor and VBAC remained necessary.
During the 1990s, managed care organizations
identified VBAC as a way to save money through shorter hospital stays and use
of less costly resources. Many such entities categorically demanded trial of
labor in all cases. In 1993, Los Angeles County–University of Southern
California Medical Center adopted a policy requiring all women meeting ACOG
criteria to attempt VBAC. They calculated that each successful VBAC cost $2300
less than repeat cesarean delivery. By 1997, the County of Los Angeles had paid
$24 million to settle 49 claims for adverse outcomes associated with VBAC.7 Millions more are
expected to be paid to provide lifetime care to children with brain injury
after labor complicated by uterine rupture. Denial of patient autonomy was
costly in both monetary value and human suffering, and the policy was abandoned
in 1995 in favor of informed patient choice.
The Los Angeles County–University of Southern
California Medical Center experience also showed that uterine rupture increased
dramatically with the number of prior cesarean deliveries.8 Such data led ACOG to
revise criteria in 1999 restricting VBAC attempts to patients with only 1 or 2
prior cesarean deliveries.9 A year later the ACOG
Task Force on Evaluation of Cesarean Delivery further restricted this to only 1
prior low transverse cesarean delivery in a hospital setting with capability
for immediate response to a maternal or fetal emergency. The task force report
analyzed the extensive literature, which generated the current recommendations
and is recommended to readers desiring further information.3
The Los Angeles experience was mirrored
nationwide as desired cost savings from trial of labor and VBAC could not be
demonstrated and cohort studies of neonates born by VBAC and elective repeat
cesarean delivery showed no significant difference in fetal morbidity.3, 6 In the current issue
of THE JOURNAL, Smith et al10 report the results of
a retrospective cohort study finding that the absolute risk of perinatal death
associated with trial of labor following cesarean delivery was low but that the
risk was significantly higher than that associated with planned repeat cesarean
delivery.
The ACOG bulletin noted that despite 800
citations in the literature, there are no randomized controlled trials to show
that maternal and neonatal outcomes are better with VBAC than with repeat
cesarean delivery.9 At present, there is
no hard evidence on the relative risks and benefits of term elective cesarean
delivery for nonmedical or nonobstetric reasons compared with vaginal delivery.11
The most severe risk in trial of labor is uterine
rupture, which occurs in the range of 0.2% to 1.5% of attempted VBAC in
patients who have a low transverse uterine scar.9 Uterine rupture can be
a catastrophe in which immediate medical response is necessary to save the life
of both mother and fetus. Rupture is most likely in patients who had classic
(fundal) or other vertical incisions with prior cesarean deliveries or uterine
perforation during termination of a prior pregnancy. Low transverse uterine
scars are more likely to rupture if the patient has had more than 1 prior
cesarean delivery. Any condition that overdistends the uterus can weaken the
scar and increase risk, including multiple gestation, polyhydramnios, or fetal
macrosomia. The earliest sign of uterine rupture usually is a fetal heart
monitor tracing showing bradycardia, tachycardia, or recurrent late
decelerations, but change in abdominal configuration, vaginal bleeding, or
maternal hypovolemic shock may herald rupture.3 To enhance early
detection and intervention most obstetricians prefer continuous internal
monitoring of the fetal heart rate with one nurse for each patient attempting
trial of labor.
The ACOG recommendation for immediate response
for a maternal or fetal emergency has correctly been interpreted to mean that
trial of labor or VBAC should not be offered in level 1 or 2 maternity units
that lack the necessary teams of obstetrician, pediatrician, anesthesiologist,
and support staff in the hospital at all times. However, this may conflict with
the philosophy of a patient seeking a natural birth experience who wishes to
ambulate, delay or refuse intravenous fluids, and have only intermittent
external fetal auscultation instead of internal fetal heart rate monitoring.
This scenario is fraught with hazard in the event of uterine rupture as the
fetal heart rate pattern is usually one of steady and often rapid deterioration
with no early warning sign. Even 5 or 10 minutes' delay can result in
significant fetal harm. Nurse midwives and family practice physicians may be
more receptive to the natural birth philosophy but must accept significant
medical-legal liability risks if they offer patients trial of labor and VBAC
and cannot provide immediate, appropriate surgical intervention in the case of
maternal or fetal deterioration.
Current standards limit acceptable candidates
for trial of labor and VBAC to patients with only 1 prior low transverse scar,
37 to 40 weeks' gestation, fetal vertex presentation, otherwise healthy
pregnancy, and who are monitored in a unit with capability to immediately
respond to maternal and fetal emergencies such as uterine rupture.3
Informed consent is essential for any patient
who requests a trial of labor. Extensive and witnessed discussion with the
patients, and documentation of this interchange, is crucial if there is
liberalization of the above criteria. This may include trial of labor in a
patient who has had 2 or more prior low transverse cesarean deliveries, an
unknown or vertical uterine scar, requested induction of labor, or preference
to deliver in a unit where time to respond to emergency might be 30 minutes or
more with potentially fatal consequences to mother, fetus, or both. Such
situations are not absolute contraindications, but require thoughtful
individualized appraisal of risks and benefits for the patient and fetus. The
ultimate decision for risk acceptance rests with the informed patient;
physicians must also choose their risk tolerance regarding availability of VBAC
in their practice.
The trend is clearly to avoid formerly
permissible situations for VBAC such as multiple gestations, premature or
postmature fetuses, possible fetal macrosomia, and unknown uterine scar, all of
which are associated with increased incidence of uterine rupture. The risk of
uterine rupture is also significantly higher when labor is induced and
particularly when a prostaglandin is used during the induction process.12 Successful VBAC is
more likely in women who have had a prior successful vaginal delivery13 but many VBAC
candidates request repeat cesarean delivery to facilitate tubal ligation.
Vaginal birth after cesarean delivery has been
promoted to decrease the cesarean delivery rate. For any individual patient the
risks of placenta previa and placenta accreta increase progressively with each
succeeding cesarean delivery14; demographic shifts
in developed nations show that many women now have only 1 or 2 children,
minimizing this particular risk.15 Many women are
delaying pregnancy. In 1970, only 4% of primiparas were older than 30 years. In
1994, that figure had increased to 21%.3 The rate of cesarean
delivery is significantly increased in women older than 30 years for many
reasons. Risks of cesarean deliveries appear to be as acceptable to many women
as the risks of vaginal birth, particularly operative vaginal delivery. Urinary
and fecal incontinence, pelvic organ prolapse, and sexual dysfunction have an
increased incidence following vaginal delivery.16 Sonographic studies
showed a 28% incidence of rectal sphincter damage in women who had visually
undamaged perineums after delivery.17 As this information
has entered the public domain, women are increasingly requesting both primary
and repeat cesarean deliveries. This is particularly true of VBAC candidates
who realize that the attempt may fail and result in a cesarean delivery in 20%
to 40% of trials of labor.9
A study of 583 000 births in California18 provides statistics
of intracranial hemorrhage in neonates. In mothers who had cesarean delivery
prior to initiation of labor, the rate of intracranial hemorrhage was the
lowest, 1 of 2750. When cesarean delivery was performed during labor, the rate
tripled to 1 of 907 and if it was done after a failed attempt to deliver
vaginally (by forceps or vacuum extraction), the incidence tripled again to 1
of 334. The present increasing cesarean delivery rate reflects in part a
decline in operative deliveries by forceps and vacuum extraction spurred by the
perception of obstetricians that resorting to cesarean delivery decreases
liability because such statistics suggest modern cesarean delivery may be safer
than operative vaginal birth.19
The above statistics also reflect in part that
fetal maturity can be determined with a high degree of success in a patient who
is monitored from early pregnancy. This permits elective scheduling of a repeat
cesarean delivery. Alternatively, repeat cesarean delivery can be done at the
first signs of labor to minimize fetal risks associated with unanticipated
prematurity.
This enhanced safety of cesarean delivery is
reflected in some international statistics. Brazil has up to 80% cesarean
delivery rate among private insurance patients and about 50% to 60% overall.20 In these settings,
VBAC is almost nonexistent, which is a stark contrast to European countries
with VBAC rates of approximately 50%.21
Currently, there is no reliable method to select
patients who will succeed at VBAC. The International Federation of Gynecology
and Obstetrics and ACOG concur that the patient should make the decision to
attempt VBAC after thorough counseling of risks and benefits.9, 22 Only the patient can
assess those relative values. Unfortunately, clear high-level scientific
evidence to guide the decision is lacking. Despite the increasing US cesarean
delivery rate, there is increasing demand for cesarean delivery by women who
must live with the consequences of adverse outcomes of trial of labor or of
traumatic vaginal births. The physicians who care for them on an individual
basis understand their concerns and their cumulative decisions produce
increasing rates for both primary and repeat cesarean deliveries.23
The situation has been further confused by the
Joint Commission on Accreditation of Healthcare Organizations (JCAHO)
designation of VBAC rates as 1 of 3 core measures of pregnancy care, which
hospitals must report for the ORYX program starting in July 2002. This JCAHO
initiative collects data for development of a nationwide database of
performance measures. Many hospital administrators, quality improvement
managers, and obstetrical units perceived this as a mandate to boost VBAC
rates. In an effort to dispel that incorrect perception, JCAHO sent a letter to
all hospitals on December 6, 2001, explaining that "[t]his measure is
configured as a neutral measure. Be aware the Joint Commission does not intend
to promote VBAC."24
This message must be understood so that
maternity units not capable of immediate emergency response will not allow
women to attempt trial of labor and VBAC under the mistaken belief that JCAHO
expects these units to provide VBAC service. Such units should not use VBAC as
a core measure, but should use the option to substitute a different measure
appropriate to their actual ranges of obstetrical care. In an unsafe setting
VBACs might well be perceived as a deficiency in obstetric care rather than a
mark of excellence.
The rise and incipient fall of VBAC exemplifies
fundamental shifts in medical care in the past 20 years. Previously, physicians
made most medical decisions; control then shifted to managed care dictates.
Increasing pressure by both physicians and the public is now shifting decisional
authority back to physicians and their patients. However, consumerism is moving
control of medical care increasingly into the hands of the patients while
physicians serve in more consultative and advisory roles. The current status is
thus a state of dynamic tension between women who want a natural birth
experience, women who want to avoid potential vaginal birth trauma, entities
promoting reduction of the cesarean delivery rate, and the individual
physicians who must care for each patient.
In 1997, an expert working group from the
Department of Health and Human Services established a 75th percentile target of
37% VBAC for suitable candidates as then defined.3 The current shift of a
much more restricted cohort of carefully selected patients into the exclusive
domain of tertiary centers, coupled with increased patient autonomy, will drive
the national VBAC rate dramatically below that goal.
Author/Article Information
Author Affiliation: Department of
Women's Health Care, Riverside County Regional Medical Center, Moreno Valley,
Calif.
Corresponding Author and Reprints:
W. Benson Harer, Jr, MD, DHL, Department of Women's Health Care, Riverside
County Regional Medical Center, 26520 Cactus Ave, Moreno Valley, CA 92555
(e-mail: [log in to unmask]).
Contempo Updates Section Editor:
Janet M. Torpy, MD, Fishbein Fellow.
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ABSTRACT
| FULL TEXT
| PDF
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