Data are adapted from a study of 71 consecutive patients treated with plasma exchange for clinically suspected TTP-HUS.33Complications occurred in 43 (61%) of patients; complications were defined as major in 21 (30%) patients and caused 2 deaths.33 No transfusion-transmitted infections were detected. With some machines and settings, unintentional plateletpheresis may be an explanation for persistent thrombocytopenia when other features of TTP-HUS have resolved.

Major complications were defined by six criteria: systemic infections, prevention of treatment, requirement for an invasive procedure, red cell transfusion, systemic therapy other than Benadryl, hydrocortisone, or CaCl₂, or transfer to an intensive-care unit. None of the patients with symptoms of alkalosis or volume depletion met criteria for a major complication. No frequency estimate is yet available for unintentional plateletpheresis. An additional 22 (31%) patients had minor complications, such as urticaria, hypotension or hypoxia, catheter obstruction that did not prevent completion of plasma exchange, and local infection at the catheter exit site.33