This Medical Video:
At one time, women who had delivered by cesarean section in the past
would usually have another cesarean section for any future
pregnancies. The rationale was that if allowed to labor, many of
these women with a scar in their uterus would rupture the uterus
along the weakness of the old scar.
Over time, a number of
observations have become apparent
Most women with a previous
cesarean section can labor and deliver vaginally without rupturing
Some women who try this will, in fact, rupture
When the uterus ruptures, the rupture may have
consequences ranging from near trivial to disastrous.
be very difficult to diagnose a uterine rupture prior to observing
fetal effects (eg, bradycardia). Once fetal effects are
demonstrated, even a very fast reaction and nearly immediate
delivery may not lead to a good outcome.
The more cesarean
sections the patient has, the greater the risk of subsequent rupture
The greatest risk occurs following a
“classical” cesarean section (in which the uterine incision
extends up into the fundus.)
The least risk of rupture is
among women who had a low cervical transverse incision.
vertical incisions probably increase the risk of rupture some, but
usually not as much as a classical incision.
Many studies have
found the use of oxytocin to be associated with an increased risk of
rupture, either because of the oxytocin itself, or perhaps because
of the clinical circumstances under which it would be contemplated.
Pain medication, including epidural anesthetic, has not
resulted greater adverse outcome because of the theoretical risk of
decreasing the attendant’s ability to detect rupture early.
The greatest risk of rupture occurs during labor, but some of the
ruptures occur prior to the onset of labor. This is particularly
true of the classical incisions.
Overall successful vaginal
delivery rates following previous cesarean section are in the
neighborhood of 70 This means that about 30of women undergoing a
vaginal trial of labor will end up requiring a cesarean section.
Those who undergo cesarean section (failed VBAC) after a lengthy
labor will frequently have a longer recovery and greater risk of
infection than had they undergone a scheduled cesarean section
Women whose first cesarean was for failure to
progress in labor are only somewhat less likely to be succesful in
their quest for a VBAC than those with presumably non-recurring
reasons for cesarean section.
For these reasons, women with a
prior cesarean section are counseled about their options for
delivery with a subsequent pregnancy Repeat Cesarean Section, or
Vaginal Trial of Labor.
They are usually advised of the
approximate 70successful VBAC rate (modified for individual risk
factors). They are counseled about the risk of uterine rupture
(approximately 1in most series), and that while the majority of
those ruptures do not lead to bad outcome, some of them do,
including fetal brain damage and death, and maternal loss of future
childbearing. They are advised of the usual surgical risks of
infection, bleeding, anesthesia complications and surgical injury to
After counseling, many obstetricians leave
the decision for a repeat cesarean or VBAC to the patient. Both
approaches have risks and benefits, but they are different risks and
different benefits. Fortunately, most repeat cesarean sections and
most vaginal trials of labor go well, without any serious
For those choosing a trial of labor, close
monitoring of mother and baby, with early detection of labor
abnormalities and preparation for