Updated 6/2024
The alphabet soup
CD—Cesarean delivery
TOLAC—Trial of labor after a cesarean. This refers to the process of attempting to have a vaginal delivery after having had a prior CD.
VBAC—Vaginal birth after cesarean. This refers to a successful vaginal delivery after having had a CD.
RCD—Repeat cesarean delivery. This refers to a CD done after having had a prior CD.
El ectiveRCD—Elective repeat cesarean delivery. This refers to a patient who has had a prior CD and desires to electively undergo a RCD prior to the onset of labor at or after 39 weeks.
LTCD—Low transverse cesarean delivery. This refers to the incision on the uterus. A low transverse uterine incision is made in the lower segment of the uterus and goes from side-to-side, much like the incision on the skin that goes from side-to-side. However, just because you have a side-to-side incision on your skin does not mean you had the same on your uterus. Some incisio
What is a trial of labor after cesarean?
If you have asked yourself this question, you are not alone! There are many reasons that a cesarean delivery (CD) is performed, but with a subsequent pregnancy, a person may choose to attempt to have a vaginal delivery, known as a 'trial of labor after cesarean" or TOLAC. Some reasons one may want to have a TOLAC include being able to hold their baby immediately after delivery, avoid another major surgery, shortened recovery time, or to simply experience a vaginal birth.
"VBAC" is the delivery of a baby vaginally after a prior CD
The process of attempting a vaginal birth after cesarean (VBAC) is called a TOLAC. If a vaginal delivery occurs, then you have had a VBAC. If you decline to attempt a TOLAC, then you will be scheduled for an elective repeat cesarean delivery (RCD).
While a TOLAC may be considered after previous CD, it is critical that a thorough review of risks and benefits of attempting a TOLAC be done with your obstetrical care provider. The decision making should incorporate a person’s preferences and desires, as well as the circumstances surrounding their previous CD.
Most people are good candidates for a TOLAC!
- 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.
Most people are candidates if they have had one previous low transverse cesarean delivery (LTCD). That means the scar on your uterus (not the skin) is horizontal in the lower part of your uterus (see image). These people can be and should be counseled and offered a TOLAC if there are no other medical complications at play or contraindications to attempting a TOLAC. Candidacy is also based on individualized assessment. Even if a patient is not the best candidate, but presents to labor and delivery in active labor, clinical judgment may be used to determine the best route for delivery. The risks and benefits of a TOLAC should be discussed between patient and provider. Decisions surrounding TOLAC should not only focus on the outcomes of that pregnancy, but should also include a discussion of future pregnancies.
This early pregnancy VBAC calculator can be used during pregnancy to help guide the decision on whether or not to attempt a TOLAC. Evidence suggests that those with at least a 60–70% likelihood of achieving a VBAC who attempt TOLAC experience the same or less maternal morbidity than those who have an elective RCD. On admission to L&D, there is a more accurate VBAC calculator (delivery admission VBAC calculator) that can be used to assess a percentage chance of success for VBAC.
...but not everyone is a candidate for TOLAC! Here is the most recent ACOG guidance:
NOT A GOOD CANDIDATE
- Previous classical or “T” incision
- Extensive transfundal uterine surgery (ex: with myomectomy)
- Contraindication for vaginal delivery such as placenta previa
- Prior uterine rupture-ACOG states, “…similar to a history of a prior classical cesarean, the suggested timing of delivery between 36 0/7 weeks and 37 0/7 weeks of gestation should be considered but can be individualized based on the clinical situation”.
OTHER CONSIDERATIONS
Macrosomia (birth weight >4,000g or 4,500g)
- Less data on VBAC
- Data on uterine rupture is inconclusive
- Isolated macrosomia does ‘not preclude’ TOLAC
- Overall lower likelihood of VBAC
- It remains appropriate for obstetric care providers and patients to consider past birth weights and current estimated fetal weight when making decisions regarding TOLAC. Suspected macrosomia alone should not preclude offering TOLAC.
Gestational Age > 40 Weeks
- Decreased VBAC rates in those who attempt TOLAC
- Data on rupture conflicting
- Gestational age > 40 alone does not mean someone cannot have a TOLAC
Previous (documented) Low-Vertical incision
- Studies show a similar rate of VBAC success
- No consistent evidence of increased risk of uterine rupture or other complications
- Provider and patient may elect TOLAC
Unknown Prior Uterine Incision
- Previous case series reported VBAC success and rupture rates similar to known low transverse scars
- If one previous cesarean and unknown scar, patient may be a candidate for TOLAC if no clinical suspicion for classical incision
Twin Gestation
- Consistent evidence shows that outcomes are similar to TOLAC with singleton gestations
- Patients twin gestation and one previous low transverse scar incision are candidates for TOLAC
Obesity
- BMI alone is not an absolute contraindication to TOLAC, but should be considered an additional risk factor that may lower chance of VBAC
- Obese patients have increased risk related to CD
More than one prior CD
- Two previous low transverse CDs should be counseled and offered TOLAC
- Data limited on >2 previous CDs
Risks and benefits of TOLAC, VBAC, and RCD
At this point, you might have some thoughts on whether or not you're a candidate for or desire to undergo a TOLAC. Now you might want to know the risks and benefits of each.
Benefits of VBAC:
- Avoidance of major abdominal surgery
- Lower rates of hemorrhage, blood transfusion, blood clots, and infection
- Shorter recovery time
- Decreased risk of maternal consequences related to having multiple cesarean deliveries (eg, hysterectomy, bowel or bladder injury, blood transfusion, infection, and abnormal placentation such as placenta previa and placenta accreta)
- Most published series examining patients attempting TOLAC have demonstrated a vaginal delivery rate of 60–80%. CD after a failed TOLAC carries more risk than planned elective RCD (see below for more info).
Risks of TOLAC:
- Infection
- Surgical injury
- Blood transfusion
- Hysterectomy
- Uterine rupture
- Most maternal complications related to TOLAC occurs when a RCD becomes necessary for any reason. For example, a patient is laboring and attempting to have a VBAC, but a CD is needed due to maternal or fetal complications. VBAC is associated with fewer complications than elective repeat cesarean delivery, whereas a failed TOLAC is associated with more complications.
- The decision to undergo TOLAC or elective RCD should be documented and included in the medical record. Clinicians should document a review of the counseling session, including the potential risks and benefits of both TOLAC and elective RCD, as well as a management plan.
Risks of elective RCD:
- Bleeding requiring blood transfusion
- Infection
- Injury to surrounding organs, including bowel and bladder.
Risks of having multiple cesarean deliveries:
- Placenta accreta spectrum disorder and placenta previa
- Operative injury: cystotomy, bowel injury, ureteral injury
- Ileus
- Need for postoperative ventilation and intensive care unit admission
- Hysterectomy
- Blood transfusion requiring 4 or more units
- Duration of operative time and hospital stay
- Maternal hemorrhage
- Thromboembolism
- Infection
More info on uterine rupture
Uterine rupture most often occurs during labor {i.e. during a TOLAC} in a patient with a prior CD and is a true obstetrical emergency. Uterine rupture occurs when the previous incision on the uterus opens up prior to or during the labor process. The risk of a uterine rupture during labor in a patient with a prior CD is largely dependent on the type of incision made on the uterus during the prior CD. As a result, it is essential to know what type of incision was made on your uterus before considering a TOLAC. Requesting the operative report from your last CD is necessary so your current provider can determine with certainty what type of incision you had on your uterus and if it is compatible with attempting a TOLAC. Finally, attempting a TOLAC at home or in any other setting than a hospital is not recommended. Hospitals who offer patients a TOLAC should have an obstetrical care provider who can manage TOLACs, as well as the complications of a TOLAC (ie uterine rupture), and anesthesia in-house 24/7.
Uterine rupture results in the most significant increase in the likelihood of additional maternal and neonatal morbidity. The risk of uterine rupture is <1% for one previous LTCD in spontaneous labor, 4-9% for previous classical or T-shaped uterine incision, and 0.9%-3.7% for >1 prior LTCD. A uterine rupture often leads to emergent CD, hysterectomy, and additional operative procedures, as well as increased maternal infection risk and need for blood product transfusion. Uterine rupture may lead to maternal injury or death and fetal injury, including severe neurological damage (rate of 0.8 per 1000 trials of labor) or even death (approx 0.13%). If induction or augmentation of labor with pitocin occurs, there is an increased risk of uterine rupture of approximately 0.9- 1.4% for one prior LTCD and 2-5% with an undocumented uterine scar. We do not have accurate stats for >1 prior LTCD.
Things that can increase or decrease your chance of having a successful VBAC
Factors that can increase the likelihood of a VBAC include:
- Having at least one prior successful vaginal delivery or VBAC
- Entering spontaneous labor on your own
- The first CD was done for a nonrecurring indication, i.e. fetal breech presentation or twins or placenta previa
Factors that can decrease the likelihood of VBAC:
- Having an induction or augmentation of labor with the TOLAC
- Being of older age
- Having a higher body mass index {BMI}
- The fetus is large {> 4000-4500 kg}
- The gestational age is beyond 40 weeks
- The first CD was done for a recurring indication, i.e. failure to dilate in labor or failure to push the baby out
- A shorter interdelivery interval (less than 19 months)
- The presence of preeclampsia at the time of delivery
Do all providers offer their patients VBACs?
Because of the significant complications that can occur, some providers do not offer TOLACs to their patients. In addition, providers may not be able to offer a TOLAC due to the limitations of the hospital or facility in which they are practicing.
For any individual undergoing a TOLAC, continuous fetal heart rate monitoring is required during the labor process. In addition, a provider who is familiar with the signs of uterine rupture and other complications of TOLAC, and who is experienced with managing a patient undergoing a TOLAC, should be present at all times in the hospital. Finally, TOLAC should occur in hospitals equipped to perform an emergent CD if needed. This means that not only does the provider need to be available in the hospital at all times, but anesthesia providers should also be present and available to provide anesthesia for labor during the TOLAC and a CD if needed. Not all hospitals require that the obstetrical care or anesthesia providers be physically present in the hospital. As a result, providers in these hospitals are not able to offer a TOLAC to their patients.
Let your provider know as early as possible if you are thinking about a TOLAC. That way if they do not offer TOLACs, you can be referred to someone who does and you can be counseled on whether you are a good candidate for a TOLAC.
Here are some additional resources for you!
ACOG Vaginal Birth After Cesarean Delivery (VBAC) FAQs
ACOG Practice Bulletin No. 205: Vaginal Birth After Cesarean Delivery
Repeat Cesareans and Failed TOLACs: It’s OK to Feel Like You Missed Out
Maternal morbidity associated with multiple repeat cesarean deliveries
MFMU Network Calculator for VBAC
Go to my "cesarean" highlight on my Instagram page or enter "TOLAC" in the search bar on this website for more info!