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Vaginal Birth After Caesarean Section (VBAC) – Introduction

For much of the 20th century, most people believed that a woman who had previously undergone a caesarean delivery would require a repeat caesarean delivery for future pregnancies. However, it appears that many women who have previously undergone caesarean delivery can safely attempt a trial of labor to have a vaginal delivery in subsequent pregnancies. The following are important definitions regarding vaginal birth after caesarean (VBAC) delivery:

  • A trial of labor after cesarean (TOLAC) is a planned attempt to labor by a woman who has previously undergone a caesarean delivery and desires a subsequent vaginal delivery
  • A VBAC is a “successful” trial of labor resulting in a vaginal birth
  • A TOLAC may result in either a “successful” VBAC or a “failed” trial of labor resulting in a repeat caesarean delivery
  • A repeat caesarean delivery may be planned and booked beforehand and this is termed an elective repeat caesarean delivery

Benefits Of Vaginal Birth After Caesarean

The benefits of a trial of labor after cesarean (TOLAC) resulting in a vaginal birth after caesarean (VBAC) include the following:

  • Shorter length of hospital stay and postpartum recovery (in most cases)
  • Fewer complications, such as postpartum fever, wound or uterine infection, thromboembolism (blood clots in the leg or lung), need for blood transfusion
  • Fewer neonatal breathing problems

Risks Of Vagina; Birth After Caesarean

The risks of an attempted VBAC or TOLAC include the following:

  • Risk of failed trial of labor after cesarean (TOLAC) without a vaginal birth after caesarean (VBAC) resulting in repeat cesarean delivery (RCD) in about 40- 50 percent of women who attempt VBAC
  • Risk of rupture of uterus resulting in an emergency cesarean delivery. The risk of uterine rupture may be related in part to the type of uterine incision made during the first caesarean delivery. A previous transverse uterine incision has the lowest risk of rupture (0.2 to 1.5 percent risk). Vertical or T-shaped uterine incisions have a higher risk of uterine rupture (4 to 9 percent risk). It is important to remember that the direction of the skin incision does not indicate the type or direction of the uterine incision; a woman with a transversal (bikini) skin incision may have a vertical uterine incision.
  • While women who attempt TOLAC and VBAC have a low risk of uterine rupture, the risk of uterine rupture is higher with VBAC than with RCD
  • The risk of fetal death is very low with both VBAC and elective repeat caesarean delivery, but the likelihood of fetal death is higher with VBAC than with elective repeat caesarean delivery. Maternal death is very rare with either type of delivery

Who Should Consider a Tolac and VBAC?

  • A trial of labor after caesarean (TOLAC) to attempt a vaginal birth after caesarean (VBAC) is an acceptable option for a woman who has undergone one prior caesarean delivery with a low transverse uterine incision, assuming there are no other conditions that would normally require a caesarean delivery (as an example, placenta previa)
  • A woman with two prior low transverse uterine incisions or a woman who requires induction of labor may also be considered candidates for VBAC with appropriate counselling
  • TOLAC with anticipated VBAC should be attempted only in those facilities capable of performing emergency cesarean deliveries

Management During Labor

In many ways, a woman who attempts VBAC is managed similarly to other women anticipating a vaginal delivery. A fetal monitor may be used to observe the baby’s heart rate and monitor for early signs of fetal distress. Medications to induce labor or improve contractions (eg, oxytocin) are used cautiously since they can increase the risk of uterine rupture. If problems occur during labor, a caesarean delivery will likely be recommended.

VBAC Success Rates

In general, 50 to 60 percent of women who are considered candidates for a trial of labor after cesarean (TOLAC) to attempt vaginal birth after cesarean (VBAC) will have a successful vaginal birth (VBAC). Factors that increase the chances for a successful VBAC in an individual woman include:

  • A previous vaginal delivery, especially a previous VBAC
  • Spontaneous onset of labor (labor is not induced)
  • Normal progress of labor, including dilation and effacement (thinning) of the cervix
  • Prior cesarean delivery performed because the baby’s position was abnormal (breech)
  • Only one prior cesarean delivery • The prior cesarean delivery was performed early in labor, and not after full cervical dilatation
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