What are the risks and considerations for a trial of labor after cesarean (TOLAC) following a high transverse C-section?

From the Guidelines

A trial of labor after cesarean (TOLAC) following a high transverse C-section is generally considered safe for most women, with success rates of 60-80%. The main risk is uterine rupture, which occurs in approximately 0.5-1% of cases, slightly lower than with low transverse incisions 1. When considering TOLAC, several factors should be evaluated:

• The number of previous cesareans (risk increases with multiple prior C-sections)
• The reason for the previous cesarean
• Maternal age
• Estimated fetal weight
• The interval between pregnancies (at least 18-24 months is recommended) 1 Continuous electronic fetal monitoring and immediate access to emergency cesarean delivery facilities are essential during labor. Induction of labor, particularly with prostaglandins like misoprostol, increases rupture risk and should be approached cautiously, as misoprostol should not be used for cervical preparation or induction of labor in women who have had a previous cesarean delivery and are in the third trimester 1. Epidural anesthesia is safe and recommended as it allows for immediate surgical intervention if needed. Women should be counseled that successful TOLAC avoids major abdominal surgery and its associated risks, shortens recovery time, and reduces complications in future pregnancies. However, a failed TOLAC resulting in emergency cesarean carries higher risks than a planned repeat cesarean. The decision should ultimately be individualized based on the woman's specific circumstances and preferences after thorough discussion with her healthcare provider, considering the benefits and harms of LAC/VBAC, including the lower risk of death and the increased risk of perinatal mortality compared to repeat cesarean delivery 1.

From the Research

Risks and Considerations for Trial of Labor after Cesarean (TOLAC) following a High Transverse C-section

• The primary cause of uterine scars is a previous cesarean, and the risks of maternal complications are rare and similar after a TOLAC and after an elective repeat cesarean delivery (ERCD), but the risk of uterine rupture is higher with TOLAC 2.
• Maternal morbidity in women with previous cesareans is higher when TOLAC fails than when it leads to successful vaginal delivery 2.
• The risk-benefit ratio considering the risks of short- and long-term maternal complications is favorable to TOLAC in most cases 2.
• TOLAC is possible for women with a previous cesarean before 37 weeks, with 2 previous cesareans, with a uterine malformation, a low vertical incision or an unknown incision, with a myomectomy, postpartum fever, an interval of less than 6 months between the last cesarean delivery and the conception of the following pregnancy, if the obstetric conditions are favorable 2.

Factors Affecting the Success of TOLAC

• A previous vaginal delivery, either before or after the cesarean, increases the likelihood of a successful TOLAC 2, 3.
• A favorable Bishop score or spontaneous labor also increases the likelihood of a successful TOLAC 2.
• Induction of labor, especially using prostaglandins, increases the risk of uterine rupture 2, 4, 5.
• Oxytocin use may increase the risk of uterine rupture, which could be influenced by the process of induction or individual cervix condition 5.

Management and Monitoring of TOLAC

• Labor should be induced in women with a previous cesarean only for medical indications 2.
• Routine use of internal tocodynamometry does not prevent uterine rupture 2.
• Epidural analgesia must be encouraged 2.
• The decision about planned mode of delivery must be shared by the patient and her physician and made by the 8th month, taking into account the individual risk factors for TOLAC failure and uterine rupture 2.

Uterine Rupture

• Uterine rupture is a serious complication both for mother and child, occurring in 0.2 to 0.8% of TOLAC 4.
• The individual risk for uterine rupture after TOLAC is multifactorial and predictive scores showed no clinical utility in routine 4.
• The risk of uterine rupture is decreased in case of previous vaginal delivery and increased in case of classical C-section, previous uterine rupture, induction of labor, more than one previous cesarean section, fetal macrosomia, and interval less than 6 months before the next pregnancy 4.