In my practice I see women nearly every day who have had a previous cesarean delivery and are interested in learning about the possibility of trying for a vaginal delivery in their current pregnancy. Vaginal delivery after cesarean can be a great option for some women as long as the process is understood. I will review the basic concepts regarding trial of labor after cesarean (TOLAC), who may be good candidate for TOLAC, the risks and benefits, and frequently asked questions.
What is the difference between a TOLAC and a VBAC?
TOLAC stands for “trial of labor after cesarean”. This is essentially the process of attempting to go through labor after having had a cesarean delivery (CD) in a prior pregnancy. VBAC stands for “vaginal birth after cesarean”. This term is used after a woman has successfully delivered vaginally after a previous CD.
Who is a candidate for TOLAC?
Women who have had 1 or 2 previous cesarean deliveries may be candidates for TOLAC. The type of CD plays a critical role in determining if you are a candidate for a TOLAC. The most common types of uterine incisions are listed below;
- Low transverse uterine incision: This is a transverse (side to side) incision made in the lower portion of the uterus. The lower portion (or segment) of the uterus is typically thin and does not contain a lot of muscle. This incision is by far the most common type of incision in a cesarean delivery. TOLAC is safe for women with this type of incision on their uterus.
- Classical uterine incision: This is a vertical (up and down) incision that is made in the thick, muscular portion of the uterus. This incision is more commonly used for delivery of very preterm babies. It is rarely used for full term deliveries, but occasionally is necessary. TOLAC is NOT safe after a classical uterine incision in a previous CD. Of note, a woman who has had fibroids removed or any other uterine surgery may not be a candidate for a TOLAC if the incision was made in the muscular portion of the uterus. If you have had uterine surgery for any reason, it is important to tell your obstetrical care provider so he/she can determine if you are a candidate for TOLAC.
It is important to know that the incision on the skin is NOT always the same as the incision on the uterus. A woman could have a transverse skin incision and still have a vertical uterine incision. All women undergoing a CD should ask the surgeon what type of uterine incision was made on the uterus.
It is also important to let your obstetrical care provider know as early as possible in your pregnancy if you desire a TOLAC because not all obstetrical care providers do TOLACs nor do all hospitals allow TOLACs. In addition, per ACOG recommendations, a TOLAC can only be attempted in a hospital setting where an obstetrical care provider and anesthesiologist are physically in the hospital. Finally, the operative report from your previous CD should be obtained if possible for your obstetrical care provider to review.
What factors improve the chance of successful VBAC?
There are several factors that may improve someone’s chance to have a successful VBAC. A history of a previous vaginal delivery or VBAC increases the chances of success. Chance for success is higher for those who go into labor spontaneously rather than being induced. If the reason for your prior CD is unlikely to occur again, such as cases of breech presentation, the chance of success is also higher.
What factors decrease the chance of successful VBAC?
If the CD was for failed labor, such as the cervix did not dilate or the baby would not come down with pushing, the chance of success is reduced. If the labor must be induced or augmented the success is lower. Other factors that may reduce the chances of successful VBAC include old maternal age, higher maternal body mass index (weight), larger baby in the current pregnancy, gestational age > 40 weeks, or a short time since the last pregnancy. Epidural has not been shown to decrease success of TOLAC.
How can my chance for success be estimated?
In general, the chance of successful VBAC is estimated at around 60-80%. This chance of success can be individualized by taking the factors discussed above into account. A common calculator used to estimate the chance of VBAC success is available online.
Why should I consider a TOLAC?
There are many reasons that a TOLAC may be a valid option for you. First, some women were not able to have vaginal delivery in a prior pregnancy and wish to have that experience. There are also many benefits of a successful VBAC (compared to a CD). One big advantage is to avoid multiple CDs since risks to the mother and fetus increase with each subsequent CD. Other benefits of having a successful VBAC include a shorter recovery time, lower risk of blood clots, less blood loss and less pain as compared to having a repeat CD.
Some of the risks include the risk for abdominal and pelvic scar tissue formation making subsequent surgeries more complicated and higher risk for hemorrhage, hysterectomy, and injury. The risk for placenta accreta and/or previa also goes up with each subsequent CD as well. Placenta previa occurs when the placenta covers the opening of the cervix. Placenta accreta occurs when the placenta becomes abnormally attached to the uterine wall, and in more severe cases the placenta may actually invade into the muscle of uterus or through the uterus into the bladder or other pelvic structures. Oftentimes, placenta previa and accreta occur together in women with a history of multiple CD. Both placenta previa and accreta require an earlier delivery, and management of placenta accreta typically involves a hysterectomy immediately after delivery of the baby with most women requiring blood transfusions.
Again, it is important to let your obstetrical care provider know as early as possible in your pregnancy if you desire a TOLAC because not all obstetrical care providers do TOLACs nor do all hospitals allow TOLACs.
What are the risks of a TOLAC?
Considering all the benefits of TOLAC why doesn’t everyone do it? There are several risks with TOLAC that everyone should discuss with their obstetrical care provider before planning to proceed with TOLAC. Most of the issues with TOLAC occur when a repeat CD becomes necessary after a “failed TOLAC”. It is important to know that there is a chance that the TOLAC will not be successful and repeat CD will be needed. When looking at the overall risks, a successful VBAC has less risk than a planned repeat CD. However, if a repeat CD is needed due to failed TOLAC, the risks are actually higher than if a planned elective repeat CD prior to labor (or without attempting a TOLAC) was done in the first place.
The most concerning risk with TOLAC is the risk of uterine rupture during labor and delivery. Uterine rupture is essentially when the scar on the uterus (from your previous CD) separates or tears during labor and delivery. When this occurs, it can lead to multiple issues including significant bleeding, injury to your bladder and uterus, stress for the baby which may cause hypoxia (low oxygen levels), and in very rare cases death of the baby and/or mom. The actual risks for the baby are very low for both elective repeat CD and TOLAC; the rate of stillbirth with an elective repeat CD is 0-0.004% as compared with 0.01-0.04% with TOLAC.
The risk of uterine rupture depends of the type of previous uterine incision you have. If it is a low transverse (the most common type) uterine incision, the risk for rupture remains very low at 0.5-0.9%. If you have had a classical uterine incision (vertical incision through the muscle of the uterus) the risk is much higher estimated at around 9%. As a result, TOLAC is not recommend in women with a prior classical uterine incision. The risk for uterine rupture increases slightly if the labor is induced (giving medications to help start labor) or augmented (giving medications to make labor more efficient), but sometimes these measures are necessary to have a successful VBAC.
VBAC in special situations:
What about two prior CDs instead of one?
TOLAC may be considered for women with up to 2 low transverse CDs. The risk for uterine rupture is estimated to be about the same with 1 versus 2 prior CD. However, the comfort level of your obstetrical care provider and the protocols of the hospital where you plan to deliver also play a significant role in whether you can attempt a TOLAC after having two prior CDs.
What if I’m pregnant with twins?
TOLAC may still be an option for you even if you have twins. There are additional risks associated with twin pregnancies and deliveries that you should discuss with your obstetrical care provider. Again, the comfort level if your obstetrical care provider is crucial.
I don’t know what my prior uterine scar is, does it matter?
If possible, you should attempt to have a copy of the operative report from your prior CD sent to your obstetrical care provider for review. If it is impossible to get a report, TOLAC may still be an option. The risk for uterine rupture in the setting of an unknown uterine incision is similar to that of a low transverse uterine incision. The one caveat is that if you had a very preterm delivery the chances of the incision being classical (vertical) is much higher and TOLAC is probably not a good option with an unknown uterine incision.
Important components to a successful VBAC:
To ensure a safe delivery for the mother and baby, women undergoing TOLAC should labor and deliver at a hospital with experienced obstetrical care providers who are skilled in identifying and managing the potential complications of TOLAC. Home birth and free standing birth centers are not considered safe locations for a TOLAC. This is because immediate operating room access with trained anesthesiologists and surgeons are needed in the event of a uterine rupture. In addition, the baby’s heart rate should be monitored with a fetal monitor continuously throughout labor and delivery. Finally, epidural anesthesia is helpful in relieving pain related to labor and is also helpful in expediting emergency CD if needed during the attempted TOLAC.
What should I do if I am interested in a TOLAC?
You should start by talking with your obstetrical care provider as early in the pregnancy as possible. The earlier you discuss with your provider, the more time you have to make your decision. Your provider will discuss the risks and benefits with you in detail and together you will make plan for your delivery.