Predicting Success of Vaginal Birth After Cesarean (VBAC) in Patients Undergoing Induction of Labor (IOL) Versus Spontaneous Labor [ID 782]

INTRODUCTION: Counseling on the likelihood of successful vaginal birth after cesarean (VBAC) is essential, because a failed trial of labor after cesarean (TOLAC) increases perinatal morbidity. Trial of labor after cesarean induction of labor (IOL) has higher rates of failure versus spontaneous TOLAC. We assessed VBAC success for TOLAC IOL and examined the utility of the VBAC calculator in predicting successful TOLAC. METHODS: An IRB-approved, retrospective cohort study of patients (2020–2023) with a history of prior cesarean birth undergoing IOL was conducted. Logistic regression comparing calculator-predicted VBAC success rates to actual VBAC success was performed. RESULTS: Of 270 patients undergoing TOLAC IOL, 138 (51.1%) had successful VBAC versus 172 (63.6%) as predicted by the VBAC calculator ( P <.0001). Successful VBAC was associated with history of prior vaginal delivery (VD) ( P =.0008), prior VBAC (<0.0001), and no history of arrest disorder ( P =.0007). VBAC occurred in 72% of patients with prior VD and 46% without prior VD. Vaginal birth after cesarean occurred in 82% of patients with prior VBAC and 43% without prior VBAC. Of those with successful VBAC, 22% had prior arrest disorder. In failed IOL, 41% had prior arrest disorder. No association was found between successful VBAC and age, body mass index, chronic hypertension, or diabetes. The VBAC calculator was documented as part of TOLAC counseling in only 31 patients (11.39%). CONCLUSIONS/IMPLICATIONS: True VBAC success rate was 51.1%. This is 20% lower than the national rate (74.3%), which does not separate IOL from spontaneous labor. Trial of labor after cesarean patients should be counseled about lower success rates of VBAC post-IOL. The VBAC calculator should be used to provide more accurate counseling in patients undergoing TOLAC IOL.