For much of the 20th century, most people believed that a woman who had previously undergone a cesarean delivery (previously termed a C-section) would require a repeat cesarean delivery for future pregnancies. From studies done after 1960, we learned that the dictum “once a cesarean, always cesarean” no longer applies. 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 scheduled beforehand and thus is an elective repeat cesarean delivery (ERCD). If the woman who plans an ERCD enters spontaneous labor before the scheduled date, this is still considered an ERCD even if delivery is unscheduled. The woman with a failed TOLAC undergoes a RCD that is unplanned and unscheduled.
BENEFITS OF VAGINAL BIRTH AFTER CESAREAN
The benefits of a trial of labor after cesarean (TOLAC) resulting in a vaginal birth after cesarean (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 VAGINAL BIRTH AFTER CESAREAN
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 cesarean (VBAC) resulting in repeat cesarean delivery (RCD) in about 20 to 40 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. (See "Patient information: C-section (cesarean delivery) (Beyond the Basics)".)
- The risk of fetal death is very low with both VBAC and elective repeat cesarean delivery (ERCD), but the likelihood of fetal death is higher with VBAC than with ERCD. Maternal death is very rare with either type of delivery.
WHO SHOULD CONSIDER A TOLAC AND VBAC?
- Both the American College of Obstetricians and Gynecologists (ACOG) and the National Institutes of Health (NIH) suggest that a trial of labor after cesarean (TOLAC) to attempt a vaginal birth after cesarean (VBAC) 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) [1,2].
- ACOG further suggests that a woman with two prior low transverse uterine incisions, or a woman with a twin pregnancy, 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 and, thus, those with an appropriate nursing staff, anesthesia team, operating room, and obstetrician or other surgeon immediately available in case an emergency cesarean delivery becomes necessary.
- A woman considering VBAC should discuss with her health-care provider the risks and benefits of VBAC versus an elective repeat cesarean delivery (ERCD) and the discussion should include plans for intervention in case of uterine rupture or another indication for an emergency cesarean delivery.
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 [Pitocin]) 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, 60 to 80 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
WHERE TO GET MORE INFORMATION
Your healthcare provider is the best source of information for questions and concerns related to your medical problem.
This article will be updated as needed on our web site (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below.
Patient level information — UpToDate offers two types of patient education materials.
The Basics — The Basics patient education pieces answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials.
Patient information: C-section (cesarean delivery) (The Basics)
Patient information: Vaginal birth after cesarean delivery (The Basics)
Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.
Patient information: C-section (cesarean delivery) (Beyond the Basics)
Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.
Choosing the route of delivery after cesarean birth
Repeat cesarean delivery
Cervical ripening and induction of labor in women with a prior cesarean delivery
The following organizations also provide reliable health information.