Exsanguination (also known colloquially as bleeding out) is the fatal process of total hypovolemia (blood loss). It is most commonly known as "bleeding to death". The word itself originated from Latin: ex ("out of") and sanguis ("blood").
Exsanguination is used, as a method of slaughter. In some places, before the incision is made, a device called a captive bolt is used. The device is placed against the skull of the animal, and penetrates to cause tissue destruction in the brain incapacitating the animal so that the procedure may take place. This procedure may not be used everywhere, and its use is forbidden for halal and kosher slaughter.
While the animal is incapacitated, a knife is fully inserted through the skin just behind the point of the jaw and below the neck bones. From this position, the knife is drawn forward severing the jugular vein, carotid artery, and trachea. Properly performed, blood should flow freely with death occurring within a few minutes.
Beyond the initial cost of purchasing a captive bolt, continued usage of the method is very inexpensive. The animal is incapacitated for the duration of the procedure, so it is one of the safest methods for the slaughterer.
Trauma (injury) can cause exsanguination if bleeding is not stymied. It is the most common cause of deaths on the battlefield (though the most common cause of death from battle is infection). Non-battlefield causes can include partial or complete amputation from use of circular saws (e.g., hand-held circular saw, radial arm saw, table saw).
Patients can also develop catastrophic internal hemorrhages, such as from a bleeding peptic ulcer or splenic hemorrhage, which can cause exsanguination even without any external bleeding. It is a relatively common cause of unexpected, sudden death in patients who seemed previously well. Blunt force trauma to the liver, kidneys, and spleen can cause severe internal bleeding as well, though the abdominal cavity usually becomes visibly darkened as if bruised. Similarly, trauma to the lungs can cause bleeding out, though without medical attention blood can fill the lungs causing drowning, in the pleura causing suffocation, well before exsanguination would occur. In addition, serious trauma can cause tearing of major blood vessels without external trauma indicative of the damage.
Alcoholics can also suffer from exsanguination. Thin-walled dilated veins just below the lower esophageal mucosa called esophageal varices may ulcerate or be torn ("Mallory-Weiss syndrome") during the violent vomiting of the alcohol leading to massive bleeding and sometimes exsanguination.