What defines a hematoma?

A hematoma is specifically defined as a localized collection of blood that accumulates beneath the skin or within tissues as a result of blood vessel damage. This condition typically occurs when blood leaks out of a damaged or ruptured blood vessel and pools in the surrounding tissue, leading to swelling and discoloration. The accumulation of blood creates a distinct area that may feel firm or swollen to the touch and can appear as a bruise on the surface of the skin.

This understanding emphasizes the nature of a hematoma as involving blood rather than other substances or conditions. While a tear in the skin can lead to bleeding and potentially result in a hematoma, it is not the direct definition of a hematoma itself. Temporary swellings from water retention or skin discoloration from sun damage do not relate to the accumulation of blood and therefore do not characterize a hematoma.