This chapter discusses the cell-based model of coagulation, regulation of coagulation, and bleeding disorders. The disorders include congenital disorders and acquired disorders such as thrombocytopenia, disseminated intravascular coagulation (DIC) and microangiopathic haemolytic anaemia. Thrombocytopenia may occur because of impaired production, sequestration, increased consumption, and enhanced degradation. Activated protein C has been shown to reduce mortality in sepsis especially in patients with DIC and multi-organ failure. During the resuscitation of patients who have suffered a major haemorrhage, factors that can contribute to associated coagulopathy are: hypothermia, metabolic acidosis, and consumption of clotting products. Heparin-induced thrombocytopenia (HIT) usually occurs 5-10 days following exposure to heparin. It is a pro-thrombotic disorder and can lead to significant venous and arterial thrombosis. HIT usually resolves following the discontinuation of heparin over a few days. Management includes the prompt removal of all heparin containing medication and the substitution of a direct thrombin inhibitor to control clotting.

This chapter focuses on the various etiologies for intracerebral hemorrhage (CH), ischemic stroke (IS), transient ischemic attack (TIA), and cerebral venous sinus thrombosis (CVST) that are caused by blood disorders. Bleeding disorders may be inherited or acquired. They include thrombocytopenia and platelet function disorders, coagulation factor deficiencies, excessive anticoagulation and hemorrhagic complications after thrombolysis. Blood disorders associated with myeloproliferative diseases and disseminated intravascular coagulation (DIC) can cause both bleeding and thrombosis. Heparin-induced thrombocytopenia (HIT), the anti-phospholipid antibody syndrome, and thrombotic thrombocytopenic purpura (TTP) are conditions that cause thrombocytopenia but are more frequently responsible for thrombosis than for bleeding. Blood transfusion therapy is recommended as the most important intervention for primary stroke prevention and secondary stroke prevention in children with sickle cell disease. Cytoreduction with hydroxyurea reduces the incidence of thrombosis in essential thrombocythemia, and aspirin reduces the incidence of thrombotic events in polycythemia vera.