A woman who has previously delivered by cesarean section (C-section) must decide whether to attempt a vaginal birth (VBAC) or schedule a repeat surgery. When a woman has had two prior C-sections, this planned attempt is called a Trial of Labor After Two Cesarean Sections (TOLAC-2). This complex medical decision requires detailed discussion and careful evaluation between the patient and her healthcare team regarding the specific risks and potential rewards.
The Possibility and Success Rates of TOLAC-2
It is medically possible for women with two prior C-sections to attempt a vaginal delivery, and this option is supported by current medical guidelines for carefully selected patients. The American College of Obstetricians and Gynecologists (ACOG) recognizes the benefits of avoiding further major surgery. However, TOLAC-2 is considered higher risk than a Trial of Labor After Cesarean (TOLAC) following only one prior C-section.
The success rate for achieving a VBAC-2 (the actual vaginal delivery outcome) varies significantly. It is typically lower than the success rate for VBAC after a single cesarean. While VBAC success rates after one C-section are often 60% to 80%, the reported success rate for VBAC-2 falls closer to the 60–70% range. Success depends highly on individual patient factors, such as having had a previous vaginal birth or a non-recurring reason for the initial C-section.
Essential Screening Criteria for Candidates
The most critical factor in determining eligibility for TOLAC-2 is the type of uterine incision used during the prior surgeries. A woman must have had two previous low transverse uterine incisions (horizontal cuts across the lower, thinner segment of the uterus). Previous classical incisions (vertical cuts in the upper uterus) or a history of uterine rupture completely rule out a TOLAC attempt due to the significantly higher risk of complications.
The reasons for the previous C-sections also play a role in candidacy. Patients whose prior surgeries were for non-recurring issues (such as breech presentation or placenta previa) are generally better candidates than those whose surgeries were due to labor arrest. Furthermore, the attempt must take place in a facility that can provide immediate, emergency care, including 24/7 in-house surgical and anesthesia teams, due to the potential for sudden complications. The patient must also meet the following physical criteria:
- Be carrying a single baby.
- Have a fetus of appropriate size.
- Be in a head-first position.
- Have no underlying health conditions, such as placenta accreta, that would contraindicate labor.
Understanding the Primary Maternal and Fetal Risks
The primary risk associated with any TOLAC, especially TOLAC-2, is uterine rupture (a tearing of the previous cesarean scar). While the absolute risk remains small, it is measurably higher for women with two prior scars compared to one. Uterine rupture is a life-threatening event for both the mother and the baby, potentially leading to emergency hysterectomy or fetal hypoxia.
TOLAC-2 is associated with a higher likelihood of uterine rupture compared to an Elective Repeat Cesarean Section (ERCS). The attempt also carries an increased chance of a failed trial, necessitating an emergency C-section. A failed TOLAC results in a higher rate of complications, including increased risk of blood transfusion and infection, compared to a successful VBAC or a planned ERCS.
Weighing TOLAC-2 Against Elective Repeat C-Section
The decision to pursue TOLAC-2 balances the benefits of a vaginal delivery against the risks of potential uterine rupture or a failed trial. A successful VBAC-2 offers advantages such as a shorter hospital stay, quicker physical recovery, and the avoidance of major abdominal surgery. Achieving a VBAC may also decrease the risk of complications in subsequent pregnancies, particularly those associated with multiple C-sections, such as placenta accreta.
Conversely, choosing an ERCS provides predictability and effectively eliminates the risk of uterine rupture during labor. Although a repeat cesarean is major surgery, it allows for scheduled delivery and avoids the increased maternal and neonatal complications associated with a failed labor attempt. The decision must be highly personalized, made only after a thorough review of the patient’s full medical history and a candid discussion of the specific success probabilities and risks involved.