The Society for Maternal-Fetal Medicine endorses an algorithm for estimating the probability of successful vaginal birth for women undergoing trial of labor after cesarean (TOLAC). The algorithm is available online in the form of an easy-to-use calculator. This calculator has significant limitations that are easily overlooked by women and providers alike. The calculator has much greater positive than negative predictive power, and it cannot predict unsuccessful TOLAC or uterine rupture. Furthermore, the calculator cannot predict rare catastrophes, such as unplanned hysterectomy, permanent injury, or death. Predictions are heavily influenced by race and ethnicity, which are social and not biological constructs. Relevant variables, such as provider attitudes and institutional differences, are not accounted for. Providers should be mindful and transparent about calculator limitations when counseling women, particularly Latina and African American women. It may be appropriate to use the calculator to inform but not restrict women's options.
Keywords: maternal morbidity; perinatal morbidity; sensitivity; specificity; trial of labor after cesarean (TOLAC); uterine rupture; vaginal birth after cesarean (VBAC).
© 2018 by the American College of Nurse-Midwives.