A Vaginal Birth After Cesarean (VBAC) is the goal for many individuals who have previously undergone a cesarean delivery. The attempt at vaginal delivery is formally known as a Trial of Labor After Cesarean (TOLAC). Success means achieving a vaginal delivery while prioritizing the safety of both the mother and baby. For appropriate candidates, the average success rate for a TOLAC typically falls between 60% and 80%, offering a viable alternative to a repeat cesarean delivery.
Determining Eligibility
Successful VBAC attempts require meeting specific medical criteria that maximize the likelihood of a safe outcome. The most important factor is the type of incision made on the uterus, not the external skin incision. A low transverse incision, a horizontal cut on the lower, thinner part of the uterus, is the safest type for a TOLAC attempt. Individuals with a classical incision (a vertical cut on the upper, muscular part of the uterus) are generally not candidates due to a significantly higher risk of uterine rupture.
Past obstetric history offers strong predictive insight into the chances of success. A person who has had at least one prior vaginal delivery has a substantially higher probability of a successful VBAC. The reason for the previous cesarean also plays a role. A non-recurring indication, such as breech presentation, suggests a higher chance of success compared to a cesarean performed for failure to progress.
The time elapsed since the previous birth also influences safety. An interpregnancy interval of less than 18 to 24 months is associated with an increased risk of uterine rupture, requiring careful counseling. A TOLAC is typically offered to those with only one prior cesarean. Some individuals with two previous low transverse cesareans may still be considered candidates after extensive discussion.
Contraindications that make a TOLAC unsafe include a history of prior uterine rupture or the presence of other uterine scars, such as those from a myomectomy. Current complications like placenta previa also prevent a safe attempt. Conditions like advanced maternal age, high body mass index, or estimated large fetal weight may lower the probability of success but do not prohibit a TOLAC.
Building a Supportive Care Team
The likelihood of a successful TOLAC is influenced by the environment and personnel surrounding the labor and delivery experience. Finding a healthcare provider genuinely supportive of VBAC is the most important non-medical step. This means selecting an obstetrician or midwife who has experience with TOLAC and expresses confidence in the process.
The hospital setting is equally important, as safety guidelines require immediate access to emergency services. The facility must be capable of performing an emergency cesarean section within a short timeframe. This requires 24-hour in-house anesthesia and operating room staff to address rare but serious complications.
Engaging support personnel enhances the overall experience and morale during labor. A doula provides continuous emotional support and comfort measures, helping to maintain confidence. The partner’s role in understanding the process and acting as an advocate is also important. The entire team should be aligned on the goal and the safety parameters.
Recognizing the Primary Safety Concern
The primary safety concern unique to a TOLAC is the risk of uterine rupture. This involves the previous cesarean scar tearing open, which can lead to significant hemorrhage and distress for the mother and baby. For individuals with one prior low transverse incision, the risk of uterine rupture is consistently low, typically cited as less than 1% (ranging between 0.5% and 1%).
Although rare, uterine rupture is a medical emergency demanding immediate intervention. Medical staff look for clinical signs, with the most common indicator being a sudden, persistent change in the fetal heart rate pattern. Sudden, severe abdominal pain or abnormal vaginal bleeding can also suggest a rupture, though these symptoms are less reliable than fetal monitoring data.
The immediate response to a suspected uterine rupture is a rapid transfer to the operating room for an emergency cesarean delivery. The goal is to deliver the baby and repair the uterine tear quickly to prevent serious complications. The low absolute risk of rupture is balanced against the benefits of a successful VBAC, such as faster recovery and avoidance of repeat abdominal surgery.
Protocols During the Trial of Labor
Once active labor begins, specific protocols monitor the safety of a TOLAC attempt. Continuous fetal monitoring (CFM) is standard practice, as changes in the fetal heart rate pattern are often the earliest sign of a developing problem, including uterine rupture. This constant surveillance allows the medical team to react swiftly to any indication of fetal distress.
The use of labor augmentation agents is approached with caution during a TOLAC. While induction is not strictly prohibited, it is associated with a higher risk of uterine rupture compared to spontaneous labor. Pitocin, used to strengthen contractions, may be used judiciously. However, cervical ripening agents like misoprostol are generally avoided in individuals with a previous cesarean scar.
Pain management options, including epidural anesthesia, are fully available and encouraged for individuals undergoing TOLAC. The notion that an epidural can mask the pain of a uterine rupture is a common misconception and is not supported by medical evidence. The labor management plan is designed to maintain a low threshold for moving to an emergency cesarean section should any safety concerns arise.