Hemorrhage

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Hemorrhage, excessive discharge of blood from blood vessels, caused by pathological condition of the vessels or by traumatic rupture of one or more vessels. Hemorrhage is a complication of many diseases. Peptic ulcer, for example, may cause hemorrhage by eroding a blood vessel. Stroke is sometimes due to hemorrhage in the brain. Hemophilia, a hereditary blood disease, is characterized by failure of the blood to coagulate. Sudden loss of more than about 1 liter (1 qt) of blood may lead to shock; unless the blood is replaced by transfusion, this shock can be fatal.

Bleeding normally stops through the process of coagulation, or clotting of the blood, and methods used to stop hemorrhage depend on stanching the flow of blood sufficiently for a clot to form. The hemorrhage is most effectively stopped by the application of pressure directly over the wound. Bleeding is also lessened by placing the body so that the wound is uppermost. A tourniquet should never be applied if there is another way to stop the bleeding, as application of a tourniquet increases the likelihood that amputation will be required.

Fibrin film and fibrin foam, plastics made from the blood protein fibrinogen, are extensively used in surgery. Fibrin foam is used in the form of a surgical sponge that rapidly stops bleeding by forming clots. Fibrin film is used to wrap nerves or tendons or as a membrane to cover the brain or other organs. Fibrin may be left without harm in the body, where it slowly dissolves.

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