Vaginal Birth after Caesarean Section (VBAC)
By Dr Shelley Rowlands, East Melbourne Obstetric Group
It used to be believed that a woman who had a caesarean birth would always need a cesarean delivery for all her babies. However many women who have previously undergone caesarean birth can safely attempt a trial of labor to have a vaginal birth delivery in subsequent pregnancies.
Benefits of vaginal birth after caesarean section
The benefits of attempting vaginal birth after a previous cesarean birth 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 vaginal birth after caesarean
The risks of an attempted labour and vaginal birth after caesarean operation include the following:
• Failure to birth vaginally, resulting in repeat cesarean delivery. This will occur 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 birth. A previous transverse ( across) 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 transverse (bikini) skin incision may have a vertical uterine incision.
• While women who attempt VBAC have a low risk of uterine rupture, the risk of uterine rupture is higher with VBAC than with repeat elective caesarean section.
• Although the risk to the baby is extremely low with both VBAC and elective repeat caesarean delivery, it is higher with VBAC than with elective repeat caesarean delivery. Maternal death is very rare with either type of delivery.
Who should consider a VBAC?
• An attempt a vaginal birth after caesarean (VBAC) is often an acceptable option for a woman who has had one previous caesarean delivery with a low transverse uterine incision, assuming there are no other conditions that would normally require a caesarean delivery (such as placenta praaevia or low lying placenta)
• A woman who has had two previous low transverse uterine incisions may also be considered for a VBAC with appropriate counselling
• VBAC should be attempted only in those hospitals capable of performing emergency cesarean deliveries if required
Management during labor
In many ways, a woman who attempts VBAC is managed similarly to other women anticipating a vaginal delivery, with a few differences. A monitor is used to observe the baby's heart rate and monitor
for early signs of fetal distress, which can indicate rupture of the uterine scar. Medications to induce labor or improve contractions (eg, oxytocin) are either avoided or used cautiously since they can increase the risk of uterine rupture. Epidural and other analgesia may be used as they would be normally. If problems occur during labor, a caesarean delivery will likely need to be performed.
VBAC success rates
In general, 50 to 60 percent of women who attempt vaginal birth after cesarean (VBAC) will have a successful vaginal birth. Factors that increase the chances for a successful VBAC in anindividual 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 previous cesarean delivery
• The previous cesarean delivery was performed early in labor, and not after full cervical dilatation
The old dictum “ once a caesarean always a caesarean” is not necessarily true. Many women who have had a caesarean birth may be able to safely birth vaginally in another pregnancy, given the right care and circumstances.
Find out more about East Melbourne Obstetric Group at www.emog.com.au