Immune thrombocytopenic purpura (or immune thrombocytopenia; ITP) is an autoimmune coagulation disorder characterized by isolated thrombocytopenia (a platelet count <100,000/microL), in the absence of any underlying disorder that may be associated with thrombocytopenia.

Aortic dissection refers to a tear in the intimal layer of the aorta causing a separation between the intima and the medial layers of the aorta.