Haemorrhage

Bleeding
Synonyms	hemorrhaging, haemorrhaging
A bleeding human finger
Classification and external resources
Specialty	Emergency medicine
ICD-10	R58
ICD-9-CM	459.0
MedlinePlus	000045
MeSH	D006470
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Bleeding, also known as hemorrhaging or haemorrhaging, is blood escaping from the circulatory system. Bleeding can occur internally, where blood leaks from blood vessels inside the body, or externally, either through a natural opening such as the mouth, nose, ear, urethra, vagina or anus, or through a break in the skin. Hypovolemia is a massive decrease in blood volume, and death by excessive loss of blood is referred to as exsanguination. Typically, a healthy person can endure a loss of 10–15% of the total blood volume without serious medical difficulties (by comparison, blood donation typically takes 8–10% of the donor's blood volume). The stopping or controlling of bleeding is called hemostasis and is an important part of both first aid and surgery.

Hemorrhaging is broken down into four classes by the American College of Surgeons' advanced trauma life support (ATLS).

This system is basically the same as used in the staging of hypovolemic shock.

Individuals in excellent physical and cardiovascular shape may have more effective compensatory mechanisms before experiencing cardiovascular collapse. These patients may look deceptively stable, with minimal derangements in vital signs, while having poor peripheral perfusion. Elderly patients or those with chronic medical conditions may have less tolerance to blood loss, less ability to compensate, and may take medications such as betablockers that can potentially blunt the cardiovascular response. Care must be taken in the assessment.

Definitions vary. One definition used is the need for more than 3 to 5 units of packed red blood cells in a day.

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