Bleeding

Bleeding, technically known as haemorrhaging (Brit.) or hemorrhaging (US) is the loss of blood or blood escape from the circulatory system.^[1]

Bleeding can occur internally, where blood leaks from blood vessels inside the body, or externally, either through a natural opening such as the vagina, mouth, nose, ear or anus, or through a break in the skin.

Desanguination is a major blood loss. Exsanguination is losing enough blood to cause death.^[2] A person does not have to lose all of their blood to die. People can die from losing half to two-thirds of their blood.^[3]

Typically, a healthy person can endure a loss of 10–15% of the total blood volume without serious medical difficulties, and blood donation typically takes 8–10% of the donor's blood volume.^[4]

The World Health Organization (WHO) established a scale to measure different degrees of blood loss, from level 0 to 4. Level 0 indicates no blood loss, whilst level 4 represents the highest level of hemorrhaging, with a risk of fatality.