Disorders of Hemostasis

Hemostasis is the process of blood clot formation and represents a coordinated response to vessel injury. It requires an orchestrated response from platelets, the clotting cascade, blood vessel endothelium, and fibrinolysis. Thrombin-stimulated clot formation and plasmin-induced clot lysis are closely related and regulated. This dynamic process is often viewed in phases: formation of a platelet plug, propagation of the coagulation cascade, formation of a clot, and fibrinolysis of the clot. Most hemostatic abnormalities are acquired and result from drugs (e.g., aspirin or warfarin [Coumadin]), from associated disease (e.g., hepatic insufficiency), or from iatrogenic causes (e.g., multiple transfusions).