Trial of Labor After Cesarean (TOLAC) is the medical term for a planned attempt to have a vaginal birth after a previous cesarean section. This option is offered to select individuals who desire to avoid the risks associated with repeat major abdominal surgery. The decision to attempt this process is a significant one in maternity care, involving a careful balance of potential risks and benefits for both the parent and the baby.
TOLAC represents the process of going into labor with the goal of a vaginal delivery, regardless of the final outcome. This planned labor attempt is distinct from the successful result, which is known as Vaginal Birth After Cesarean (VBAC). An individual is undergoing TOLAC from the onset of labor until delivery, either vaginally or through an emergency cesarean. The alternative is an Elective Repeat Cesarean Section (ERCS), where surgery is scheduled before labor begins.
Defining Trial of Labor After Cesarean (TOLAC) and VBAC
TOLAC is the attempt to achieve a vaginal delivery after a prior cesarean birth. If the labor attempt is successful, the outcome is officially recorded as a VBAC. Not all TOLAC attempts result in a VBAC; sometimes the trial fails and requires an emergency cesarean delivery. Overall, the rate of successful VBAC after a TOLAC attempt is high, generally falling within the range of 60% to 80% nationally.
Medical Criteria for TOLAC Eligibility
Suitability for TOLAC is determined by specific medical history factors, primarily focusing on minimizing the risk of uterine rupture. The most important factor is the type of incision made into the uterus during the previous cesarean delivery. A low-transverse uterine incision, which is horizontal, is the most favorable type for a TOLAC attempt.
A classical incision, which is vertical and extends into the upper segment of the uterus, is considered a contraindication due to a significantly higher risk of rupture during labor. Individuals with only one prior cesarean with a low-transverse incision are the primary candidates for TOLAC. Those with two prior low-transverse cesarean deliveries may still be candidates, but they face increased risks.
Other historical factors influence the likelihood of success, including the reason for the previous cesarean. A prior cesarean for a non-recurring issue, such as a breech presentation, suggests a higher chance of successful VBAC than a delivery due to a failure to progress in labor. Having had a prior vaginal delivery, even before the cesarean, is the strongest predictor for a successful VBAC. The facility must be immediately equipped with the staff and resources to perform an emergency cesarean delivery.
Management and Monitoring During the Trial of Labor
The management of a TOLAC in the labor and delivery unit is similar to that of any laboring individual, but with specific, heightened safety protocols. Continuous electronic fetal monitoring is required throughout the labor process. This monitoring is necessary because the earliest sign of a severe complication, such as a uterine rupture, is often a sudden change in the baby’s heart rate, specifically fetal bradycardia.
Intravenous (IV) access is typically established to ensure rapid access for fluids, medications, or blood products if an emergency arises. The hospital must maintain immediate readiness for an emergency surgical delivery, requiring an obstetrician, an anesthesiologist, and operating room staff to be readily available. While labor induction is an option, certain agents, like some prostaglandins, are avoided due to their association with an increased risk of uterine rupture.
The use of an epidural for pain relief is permissible and does not increase the risk of complications during TOLAC. The use of oxytocin to augment labor is managed with caution, as excessive stimulation can increase the strain on the uterine scar. The goal of this specialized management is to maximize the chance of a successful vaginal birth while ensuring the ability to intervene rapidly if complications arise.
Weighing the Outcomes: Risks Versus Benefits of Success
The most serious risk associated with TOLAC is uterine rupture, which is the tearing of the prior cesarean scar. While this complication is rare, occurring in approximately 0.5% to 1% of TOLAC attempts, it can be catastrophic, leading to severe hemorrhage and life-threatening consequences for both the parent and the baby. The risk of rupture is slightly elevated if labor is induced or augmented with medication.
The benefits of a successful VBAC are substantial and include a faster postpartum recovery and a shorter hospital stay compared to a repeat cesarean. A VBAC avoids the cumulative risks associated with multiple abdominal surgeries, such as developing scar tissue, infection, and complications in future pregnancies like placenta previa or placenta accreta. Avoiding a repeat cesarean also carries a lower risk of hemorrhage and blood transfusion.
If the TOLAC attempt is unsuccessful, the individual must undergo an emergency cesarean delivery. This is associated with a slightly higher rate of complications, such as infection or excessive bleeding, than a planned ERCS. The decision requires a thorough discussion of the individual’s specific risk factors and the likelihood of success balanced against the serious, though rare, risk of uterine rupture. Ultimately, the choice to pursue TOLAC is personal and made after consultation with healthcare providers.