Postpartum Readmission for Pregnancy-Associated Thrombotic Microangiopathy Is Associated With Poor Maternal Outcomes

The postpartum period represents a high-risk interval for presentation with a pregnancy-associated thrombotic microangiopathy (TMA). Given the possibility of immune thrombotic thrombocytopenic purpura, postpartum TMA is typically treated with initiation of therapeutic plasma exchange (TPE). Yet, TPE use in postpartum TMA and its impact on maternal outcomes are poorly understood. Therefore, this study sought to determine the incidence of TPE-treated postpartum TMA and its impacts on maternal outcomes. In a retrospective cohort analysis of the Nationwide Readmission Database, we first identified patients with an index delivery hospitalization and then identified any readmissions within 30 days. Readmissions were categorized according to TMA status (no TMA vs. postpartum TMA). Postpartum TMA readmissions were identified using validated International Classification of Diseases codes for TMA (M31.1) and TPE (6A550Z3 and 6A551Z3). We then estimated the national incidence of postpartum TMA readmissions and the risk of the primary composite outcome of mortality, thrombosis, and major bleeding. Among 11 378 671 delivery hospitalizations, we identified 41 postpartum TMA readmissions (incidence 3.6/1 000 000 deliveries). Compared to non-TMA readmissions, postpartum TMA readmissions were associated with higher rates of the composite outcome (26.8% vs. 4.7%; p < 0.001). Postpartum TMA readmissions were also associated with higher rates of thrombosis (p = 0.03), major bleeding (p < 0.001), and mortality (p = 0.001). Although rare, postpartum TMA is associated with poor maternal outcomes. Future studies should explore strategies to improve outcomes in this high-risk population.