How does a hematoma differ from an ordinary bruise?

While the terms are sometimes used interchangeably, a bruise (or contusion) and a hematoma differ primarily in their presentation and severity.

A bruise is a common injury where blood from damaged vessels collects near the surface of the skin, resulting in characteristic discoloration. It is essentially a minor, superficial hemorrhage.123

A hematoma, by contrast, is a broader term for a pooling of blood in tissues or spaces outside of blood vessels. While a bruise is a type of hematoma that is visible near the skin's surface, a hematoma can also form deep within the body, such as in muscles, organs, or within the skull.4

Key differences include:
* Location: Bruises are superficial; hematomas can occur anywhere, including deep tissues or vital organs.43
* Severity: Most bruises are harmless and heal on their own. While many hematomas are also harmless, those occurring in the brain or resulting from damage to large blood vessels can be life-threatening and may require surgery.124
* Physicality: Hematomas often involve a distinct mass or swelling, whereas bruises are primarily defined by skin discoloration.14