Vaginal Birth After Cesarean Section (VBAC)
For much of the 20th century, most people believed that a woman who had previously undergone a cesarean delivery would require a repeat cesarean delivery for future pregnancies. However, it appears that many women who have previously undergone cesarean 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 cesarean (VBAC) delivery:
- A trial of labor after cesarean (TOLAC) is a planned attempt to labor by a woman who has previously undergone a cesarean 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 cesarean delivery
- A repeat cesarean delivery (RCD) may be planned and booked beforehand and this is termed an elective repeat cesarean delivery
Benefits Of Vaginal Birth After Cesarean
The benefits of a trial of labor after cesarean resulting in a vaginal birth after cesarean 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 Cesarean
The risks of an attempted VBAC or TOLAC include the following:
- Risk of failed trial of labor after cesarean without a vaginal birth after cesarean resulting in repeat cesarean delivery 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 cesarean 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 cesarean delivery, but the likelihood of fetal death is higher with VBAC than with elective repeat cesarean delivery. Maternal death is very rare with either type of delivery
Who Should Consider a TOLAC and VBAC?
- A trial of labor after cesarean to attempt a vaginal birth after cesarean is an acceptable option for a woman who has undergone one prior cesarean delivery with a low transverse uterine incision, assuming there are no other conditions that would normally require a cesarean 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 counseling
- 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 cesarean 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 to attempt vaginal birth after cesarean will have a successful vaginal birth. 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
FREQUENTLY ASKED QUESTIONS
What are some of the benefits of a VBAC?
A successful VBAC has the following benefits:
- No abdominal surgery
- Shorter recovery period
- Lower risk of infection
- Less blood loss
Many women would like to have the experience of vaginal birth, and when successful, VBAC allows this to happen. For women planning to have more children, VBAC may help them avoid certain health problems linked to multiple cesarean deliveries. These problems can include bowel or bladder injury, hysterectomy, and problems with the placenta in future pregnancies. If you know that you want more children, this may figure into your decision.
What are the risks of a VBAC?
Some risks of a VBAC are infection, blood loss, and other complications. One rare but serious risk with VBAC is that the cesarean scar on the uterus may rupture (break open). Although a rupture of the uterus is rare, it is very serious and may harm both you and your fetus. If you are at high risk of rupture of the uterus, VBAC should not be tried.
Why is the type of uterine incision used in my previous cesarean delivery important?
After cesarean delivery, you will have a scar on your skin and a scar on your uterus. Some uterine scars are more likely than others to cause a rupture during VBAC. The type of scar depends on the type of cut in the uterus:
- Low transverse—A side-to-side cut made across the lower, thinner part of the uterus. This is the most common type of incision and carries the least chance of future rupture.
- Low vertical—An up-and-down cut made in the lower, thinner part of the uterus. This type of incision carries a higher risk of rupture than a low transverse incision.
- High vertical (also called “classical”)—An up-and-down cut made in the upper part of the uterus. This is sometimes done for very preterm cesarean deliveries. It has the highest risk of rupture.
How do I know what type of uterine incision I had with a past cesarean delivery?
You cannot tell what kind of cut was made in the uterus by looking at the scar on the skin. Medical records from the previous delivery should include this information. It is a good idea to get your medical records of your prior cesarean delivery so your obstetrician–gynecologist (ob-gyn) or other health care professional can review them.
Where can I have a VBAC?
VBAC should take place in a hospital that can manage situations that threaten the life of the woman or her fetus. Some hospitals may not offer VBAC because hospital staff do not feel they can provide this type of emergency care. You and your ob-gyn or other health care professional should consider the resources available at the hospital you have chosen.
Are there things that can happen during labor that may change my delivery plan?
If you have chosen to try a VBAC, things can happen that alter the balance of risks and benefits. For example, you may need to have your labor induced (started with drugs or other methods). This can reduce the chances of a successful vaginal delivery. Labor induction also may increase the chance of complications during labor. If circumstances change, you and your ob-gyn or other health care professional may want to reconsider your decision.
The reverse also may be true. For example, if you have planned a cesarean delivery but go into labor before your scheduled surgery, it may be best to consider VBAC if you are far enough along in your labor and your fetus is healthy.