Diagnostic criteria for preeclampsia, preeclampsia with severe features/HELLP syndrome, and eclampsia are adapted and simplified from the American College of Obstetricians and Gynecologists.^13,14  Diagnostic criteria for TTP are from the randomized controlled trial documenting efficacy of plasma exchange.¹⁶  Diagnostic criteria for C-TMA are from the clinical trials that supported approval of eculizumab (described in these studies as atypical hemolytic–uremic syndrome).²¹