345: Twin Trial of labor after cesarean is an independent risk factor for adverse perinatal outcome

Abstract

To determine factors associated with a successful twin trial of labor after caesarean section (TOLAC) and compare maternal and neonatal outcomes for TOLAC in twin versus singleton gestations. A retrospective cohort was conducted at a single medical centre, in a population highly motivated for TOLAC (>80%) with about 10,000 deliveries per year between the years 2012-2017. The effect of maternal demographic and obstetrical characteristics on the likelihood of twin TOLAC success was analysed. For statistical purposes, combined adverse outcome (uterine rupture, Apgar <7 at 5 minutes and umbilical cord pH < 7.1) was compared between the singleton and twin groups. Data was analysed using Fishers exact test and chi squared tests. 95 women with a twin gestation and one previous caesarean section comprised the study group. 5703 women with a singleton gestation and one previous caesarean section comprised the control group. 29 (30.5%) and 4734 (83%) women with twin and singleton gestation respectively underwent a trial of labor (p=0.00, OR 0.087, 95% CI 0.056 - 0.135). Mean gestational age in the twin group was 36.7± 1.5 weeks. Women in the twin TOLAC group were less likely to succeed (75.9% Vs 92.7%, p=0.004, OR 4.02 95% CI 1.71-9.48) and less likely to have a spontaneous unassisted vaginal delivery (p=0.003, OR 3.4 95% CI 1.6-7.2) compared to women in the singleton TOLAC group. Maternal age less than 35, parity greater than two and at least one previous VBAC increased the likelihood of TOLAC success. Statistically significant differences were found between the twin TOLAC and the singleton TOLAC group for uterine rupture, [2 cases (6.9%) vs 20 cases (0.4%) respectively, (p=0.008, OR 17.5, 95% CI 3.89 – 78.4)] and for combined adverse outcome (p=0.004, OR 10.81, 95% CI 3.17-36.9). Twin TOLAC is not common, even in extremely highly motivated parturients for TOLAC. Our results demonstrate that even in a selected population, women undergoing twin TOLAC are less likely to have a successful spontaneous vaginal delivery and have a higher risk for uterine rupture and combined adverse perinatal outcome. Demographic and obstetric risk factors were identified and may aid the attending obstetrician in the challenging counselling of such cases.