Venn diagram of thrombotic microangiopathy and disseminated intravascular coagulation. As described in the text, the authors used the term “TMA”, which excludes DIC. The most popular thrombotic microangiopathy is HUS, which involves Shiga toxin. Atypical HUS is caused by chronic, uncontrolled, and excessive activation of complement-inducing platelet activation, endothelial injury, white cell recruitment, and activation, leading to TMA. Most cases of TTP arise from inhibition of the enzyme ADAMTS13, a metalloprotease responsible for cleaving large multimers of von Willebrand factor. A rare form of TTP is caused by genetically inherited dysfunction of ADAMTS13. This form is called Upshaw-Schülman syndrome. DIC is not a distinct disease entity. It occurs as a secondary complication of many different disorders, including sepsis, trauma, cancer, obstetric complications, and others.