Trial of labour after caesarean delivery.

Trial of labour after cesarean (TOLAC) is a safe alternative to repeat cesarean delivery1

Pregnant people who have had a previous cesarean delivery can have a TOLAC or an elective cesarean. For patients with high likelihood of vaginal birth after cesarean (VBAC), TOLAC is the recommended mode of delivery.2 A tool to calculate likelihood of VBAC is available (https://mfmunetwork.bsc.gwu.edu/web/mfmunetwork/vaginal-birth-after-cesarean-calculator).3

Three-quarters of people who attempt TOLAC will have a VBAC1

Vaginal birth after cesarean is more likely in patients with a previous vaginal delivery (83%) or VBAC (94%).1 In comparison, the probability of vaginal delivery in a primiparous term patient in Canada is 76%.4 Induction of labour decreases likelihood of VBAC, but is safe with mechanical cervical ripening, oxytocin and amniotomy.2

Uterine rupture is a rare complication of TOLAC1,2

Uterine rupture at the site of the uterine scar complicates 0.47% of TOLAC attempts.1 Risk of rupture increases with 2 or more cesarean deliveries (1.6%), less than 18 months between deliveries (4.7%), or induction of labour (1.2%).1,2

Hospital-based care is required for TOLAC

Continuous fetal heart monitoring is required during active labour. The most common sign of uterine rupture is an abnormal fetal heart tracing, particularly complicated variable, late or prolonged decelerations.1,2 If uterine rupture is suspected, an emergency laparotomy and urgent delivery are required. Therefore, onsite surgical and anesthesia teams are needed to support TOLAC.2

Patients should be counseled regarding their eligibility for TOLAC

Early counselling about TOLAC and the recommended 18-month inter-delivery interval after cesarean may increase its acceptance, leading to lower cesarean delivery rates.5 Absolute contraindications to TOLAC are previous or suspected inverted T or vertical uterine incision, previous uterine rupture or major uterine reconstruction, including myomectomy.2 If the previous uterine incision orientation is unknown, TOLAC is not contraindicated unless the cesarean was for a very preterm infant, as this increases the likelihood of vertical incision.1,2