DIC is usually associated with other signs of accelerated clot formation and dissolution, such as reduced fibrinogen levels, elevated levels of d-dimer or other fibrin split products, and possibly an increased activated partial thromboplastin time (aPTT) or prothrombin time (PT) [see following]. Although rare to develop in the ICU, patients may also present with other thrombotic microangiopathies, such as TTP-hemolytic uremic syndrome (HUS). In these cases, thrombocytopenia results from platelets aggregating with abnormally large vWF multimers that result from a deficiency in a vWF-cleaving protease.37 The often profound thrombocytopenia is accompanied by elevated serum lactate dehydrogenase levels and the presence of schistocytes on the peripheral smear representing mechanical destruction of erythrocytes.38 Only microangiopathic hemolytic anemia and thrombocytopenia are required for the diagnosis, despite the description of a “classic pentad” of TTP-HUS, which also includes renal dysfunction, neurologic abnormalities, and low-grade fever.39 Numerous conditions, including cancer, pregnancy, autoimmune conditions such as antiphospholipid antibody syndrome, and pneumococcal infection can be associated with “TTP-like” syndromes. Likewise, medications, such as cyclosporine, clopidogrel, and some chemotherapeutic agents, can produce a similar syndrome.14 The absence of an increased aPTT or PT in patients with TTP-HUS can sometimes help differentiate it from DIC, which also can have schistocytes on the peripheral smear. Unfortunately, increased coagulation parameters are not universally present in DIC, making the distinction difficult at times. Low fibrinogen levels and prolonged thrombin times are also commonly present in patients with DIC but rarely occur with TTP-HUS (Table 2). A temperature >39°C (102°F) may also help to distinguish DIC from TTP-HUS because fever, when present in the latter condition, is almost always low grade.40 Hemolysis, elevated liver enzymes, and low platelets (HELLP) syndrome of pregnancy represents another condition with hemolysis and thrombocytopenia that may be difficult to discriminate from TTP-HUS14 (Table 2). Elevated liver enzymes may be helpful in differentiating the two, but the pregnant state itself is less helpful because it is also a risk factor for TTP. However, HELLP primarily occurs during the third trimester, so thrombocytopenia prior to 20 weeks of gestation is almost never HELLP syndrome. Because HELLP syndrome usually resolves within 72 h of delivery, continued worsening of thrombocytopenia beyond this time should prompt the strong consideration of TTP.