The clinical course of patients with TTP may be complex and cannot be easily represented by a single diagram. Continued search for alternative etiologies for the patient's clinical features is critical, even after beginning plasma exchange. The clinical basis for suspecting severe ADAMTS13 deficiency is described in the text. Exacerbations of TTP, either while continuing daily plasma exchange or after plasma exchange is stopped, and relapses rarely occur in patients without ADAMTS13 deficiency. Although rituximab may be appropriate for 3 different situations illustrated in this algorithm, we have never used more than a single course of rituximab for any patient. Definitions for response, exacerbation, remission, and relapse have been previously described.17 Broken lines represent complications that occur in a minority of patients. PEX indicates plasma exchange. CVC indicates central venous catheter.
