A Vaginal Birth After Two Cesarean Sections (VBA2C) occurs when a patient who has undergone two prior C-sections attempts to deliver their next baby vaginally. This choice represents a trial of labor after cesarean (TOLAC). It requires careful review of the patient’s obstetrical history and extensive counseling regarding the associated risks and benefits. Medical guidelines recognize VBA2C as a reasonable option for appropriately selected patients, though the process is highly monitored and requires specific hospital resources.
Eligibility Requirements for a VBA2C Attempt
The decision to attempt a VBA2C is governed by strict medical criteria focused on minimizing the risk of uterine rupture. The most significant factor is the type of incision used during the two previous C-sections. Only a history of two prior low transverse uterine incisions allows for a VBA2C attempt. This horizontal cut heals with the greatest strength and is least likely to tear during labor.
A patient is excluded from a VBA2C if there is a history of any prior uterine rupture or extensive uterine surgery, such as a myomectomy to remove fibroids that entered the uterine cavity. These factors create a structurally weaker uterus, making a trial of labor too hazardous. A shorter interval between the last C-section and the current pregnancy, particularly less than 18 months, is associated with an increased risk of the uterine scar separating or rupturing.
The reason for the previous C-sections influences eligibility. Patients whose prior C-sections were for non-recurring issues, such as a breech presentation or placenta previa, are better candidates than those whose surgeries were due to labor arrest from cephalopelvic disproportion. Having had a prior vaginal delivery significantly increases the likelihood of a successful VBA2C.
Understanding the Success Rates and Safety Profile
For carefully selected candidates, the success rate for an attempted VBA2C is reported to be around 71% to 72% in large studies. Most patients who meet the strict eligibility criteria and attempt a trial of labor will achieve a vaginal delivery. This success rate is only slightly lower than the rate for a vaginal birth after a single cesarean (VBAC).
The main concern associated with a VBA2C attempt is the risk of uterine rupture, where the old C-section scar tears open during labor. The reported rate of uterine rupture during a trial of labor after two cesareans ranges from approximately 0.9% to 1.8%. While this absolute risk remains low, it is higher than the risk associated with a planned repeat cesarean section (RCS), which is around 0.01% to 0.1%.
A successful VBA2C is linked to benefits such as a faster recovery, a shorter hospital stay, and a reduced risk of complications like placenta accreta in future pregnancies compared to an RCS. However, an unsuccessful attempt resulting in an emergency C-section carries higher risks for the mother, including hemorrhage, infection, and the need for a blood transfusion, compared to a planned RCS. The absolute risk of severe adverse outcomes for the baby, such as perinatal death or neurologic injury, is also slightly higher with an attempted VBA2C than with a planned RCS, though both risks are very low.
Navigating the Labor and Delivery Experience
Once a patient is deemed eligible and chooses to pursue a VBA2C, the labor and delivery process must take place in a specific medical environment. The hospital must be fully equipped to handle an emergency, requiring immediate, 24-hour access to an operating room, anesthesia personnel, and a blood bank. This preparation ensures that an emergency C-section can be performed rapidly if signs of a complication arise.
Continuous electronic fetal monitoring is a mandatory component of the labor process for a VBA2C. The fetal heart rate tracing is the primary indicator of a potential uterine rupture, often manifesting as specific changes in the baby’s heart rate pattern. This constant monitoring allows the medical team to detect distress and intervene quickly to prevent serious harm to the baby.
Methods to induce or speed up labor are restricted during a VBA2C attempt due to their potential to increase the risk of uterine rupture. While induction is not strictly prohibited, certain medications used to ripen the cervix, such as misoprostol (a prostaglandin), are contraindicated. If labor augmentation is necessary, oxytocin may be used cautiously and with a heightened level of oversight. The medical team maintains a higher level of presence and vigilance throughout the entire labor process.