The typical manifestation of thrombotic thrombocyto-penic purpura (TTP) is the pentad of microangiopathic hemolytic anemia (MAHA), thrombocytopenia, neuro-logic abnormalities, fever, and renal failure. However, the essential features of TTP are MAHA and thrombo-cytopenia [1], and diffuse microthrombitic lesions in the small blood vessels of one or more organs characterize the pathology of the syndrome. The central nervous sys-tem and kidney have been the most common target or-gans and, thus, the pentad of TTP has been derived. However, microthrombotic manifestation can occur in other organs, including the liver, kidneys, ocular regions, pancreas, and skin, resulting in predominant dysfunction of the particular organs, such as HELLP syndrome [2], hemolytic-uremic syndrome [3], macular detachment, choriocapillaris occlusion and retinal detachment [4], pancreatitis [5], and gangrenous skin lesions [6].An unusual case of TTP presenting as acute respira-tory distress syndrome (ARDS) and later recurring as acute non-occlusive mesenteric ischemia (NOMI) is en-countered. The clinical features of the patient are pre-sented and possible pathogenesis is discussed.

Acute thrombotic thrombocytopenic purpura (TTP) occurred in three patients following abdominal surgeries. One patient underwent extensive lysis for intestinal adhesions with bowel resection, another cholecystectomy for acute cholecystitis, and the third right colectomy and partial intestinal resection for colon cancer. The diagnosis of acute TTP was established on the basis of absent hematologic features of TTP prior to surgery and development of microangiopathic hemolytic anemia (MAHA), thrombocytopenia, and unexplained mental changes after surgery. Hematologic evidence of TTP developed 3 to 9 days after surgery. Other clinical features were acute respiratory distress syndrome (ARDS) in two patients and peripheral digit ischemic syndrome (PDIS) also in two patients. In all three patients, establishing the diagnosis of TTP was delayed. Exchange plasmapheresis in one patient was ineffective due to associated ARDS and two others died soon after the diagnosis was established. In view of our experience, postoperative TTP should be considered in the differential diagnosis of the patient who develops unexplained anemia and thrombocytopenia following an abdominal surgery. Presence of hemolytic anemia, schis-tocytosis, and unexplained thrombocytopenia should alert the possibility of TTP.

Release of unusually large von Willibrand factor (UL v WF)vmultimers and a deficiency of vWF metalloprotease may result in thrombotic thromocytopenic purpura (TTP), a life threatening disease. Surgery has been associated with TTP, probably by releasing massive amounts of UL v WF. An association bwteeen TTP and orthopedic surgery has never been reported inthe literature. We report a case of TTP following a total knee replacement surgery in which prior use of ticlopidine mighthave played a role.