Maximum dose of oxytocin and the risk of uterine rupture in women attempting vaginal birth after cesarean (VBAC)

Abstract

ATTEMPTING VAGINAL BIRTH AFTER CESAREAN (VBAC) ALISON CAHILL, ANTHONY ODIBO, DAVID STAMILIO, JEFFREY PEIPERT, ERIKA STEVENS, GEORGE MACONES, Washington University in St Louis, Obstetrics/Gynecology, St. Louis, Missouri, Washington University in St. Louis, Obstetrics and Gynecology, St. Louis,Missouri, WashingtonUniversity in St. Louis, St. Louis,Missouri OBJECTIVE: To determine if the maximum dose of oxytocin impacts the risk of uterine rupture in women who attempt vaginal birth after cesarean (VBAC). STUDY DESIGN: We conducted a retrospective, multi-center cohort study of women with a history of at least one prior cesarean delivery. Date on maternal demographics, health history, pregnancy, labor, delivery, and maternal outcomes were collected from medical record review. We compared uterine rupture rates between VBAC candidates that did and did not receive oxytocin and analyzed the association between maximum dose of oxytocin (5, 10, 20, and 30mili-units/min) and uterine rupture. Bivariate and multivariate analyses were performed. RESULTS: Of the 13,523 patients with at least one prior cesarean delivery who elected a VBAC trial, 128 experienced a uterine rupture and 80 of these ruptures were in women who received oxytocin (62.5%). There was evidence of ‘‘dose response’’ for maximum oxytocin amount and uterine rupture, with increasing doses associated with a higher risk of rupture. CONCLUSION: In women attempting VBAC, as the maximum dose of oxytocin used increases, so does the risk of uterine rupture. However, even at the highest maximum dose, the absolute risk of uterine rupture remains low, suggesting that standard oxytocin protocols can be safely used in women attempting VBAC.