No guarantees are made with respect to accuracy or timeliness of this material. M.D. Bleeding disorders may complicate many routine otolaryngology procedures. This may result from technical errors, but bleeding associated with defects in the coagulation system may be difficult to control. All otolaryngologists should be aware of common bleeding disorders and their treatment. The initial vascular response of vasoconstriction occurs immediately after the injury.
Platelet adherence occurs in response to collagen exposure by endothelial damage.
Further platelet adhesion is mediated through specific platelet receptors and mediators creating an unstable hemostatic plug. Coincident with the platelet activation, the coagulation cascade is initiated by the release of tissue thromboplastin and contact-activating factors. The coagulation cascade forms a fibrin matrix that reinforces the platelet plug. Defects of the Factor VIII macromolecule are associated with the two most common inherited coagulation disorders, hemophilia A and von Willebrand's Disease. The Factor VIII macromolecule is a high molecular weight glycoprotein present in small amounts in normal plasma.