In cases of subsequent pregnancy with a scarred uterus following a prior cesarean section, the choice of delivery method often lies between a repeat cesarean section or a trial of labor after cesarean (TOLAC). A successful vaginal birth after cesarean (VBAC) can reduce the need for repeat cesarean deliveries and lower the risk of maternal and neonatal complications.
The success rate for TOLAC is generally around 60%–70%, with the incidence of uterine rupture typically below 1%. For pregnant individuals with a scarred uterus, a thorough review of medical history should be conducted during the first prenatal visit. This process includes an assessment of the patient’s general condition and a detailed inquiry into factors such as prior vaginal delivery history, gestational age at the time of the previous cesarean section, indications for the prior cesarean (particularly cephalopelvic disproportion or labor abnormalities), timing of the previous cesarean (scheduled, emergency, or performed during labor), degree of cervical dilation during the previous delivery, uterine incision type and suturing method, presence of surgical complications (e.g., uterine incision tears, postpartum hemorrhage, or infection), neonatal birth weight, and neonatal survival status. TOLAC can be considered for individuals whose interdelivery interval is ≥18 months.
Indications
Candidates include those with a history of one previous lower-segment cesarean section and no contraindications to vaginal trial of labor.
Contraindications
Contraindications include a history of uterine rupture, a history of classical cesarean section with a high vertical uterine incision, more than two prior cesarean sections, "T" or "J" shaped uterine incisions, extensive uterine fundal surgery, lower-segment vertical incisions, or other maternal complications precluding vaginal delivery. Additionally, TOLAC is not suitable if the hospital cannot provide conditions for an emergency cesarean section.
TOLAC Labor Management
After the onset of labor, preoperative preparations should be in place. Continuous electronic fetal heart rate monitoring is used during labor to enable early detection of signs of uterine rupture. Abnormal fetal heart rate patterns are typically the earliest and most common indication of uterine rupture. During labor progression, special attention should be paid to tenderness in the scarred area, particularly during the intervals between contractions. Other signs of uterine rupture include abnormal vaginal bleeding, hematuria, hypovolemic shock, elevation of the fetal head position, or retraction of the fetal head into the vaginal canal. Labor progression should be closely monitored, and vigilance is required in cases of slow labor progression, particularly during a prolonged active phase or when fetal head descent is obstructed, as these situations may indicate an increased risk of uterine rupture. In such cases, the criteria for proceeding with a repeat cesarean delivery should be relaxed. If uterine rupture is suspected or diagnosed, an emergency response protocol must be activated, and an urgent laparotomy should be performed.