Disseminated intravascular coagulation (DIC) is a conditon where the physiological generation of thrombin becomes unregulated.
A wide variety of triggers may cause release of thrombin into the circulation with consequent formation of microthrombi. It is these thrombi that cause tissue ischaemia and necrosis.
In an attempt to maintain vascular patency the fibrinolytic system becomes activated. Unregulated fibrinolysis and systemic fibrinogenolysis occurs with release of plasmin into the circulation.
The unregulated generation of thrombin and plasmin results in the thrombotic and haemorrhagic features of DIC.