What is referred to by the term hematoma?

A hematoma is a localized collection of blood outside of blood vessels, typically due to a break in the wall of a blood vessel. This term specifically refers to the swelling caused by the accumulation of blood in the surrounding tissues. It often occurs in response to an injury where blood vessels are damaged, causing blood to leak into the surrounding interstitial tissues, leading to the characteristic swelling and discoloration.

The other options indicate different medical conditions: fluid collection under the skin typically describes an effusion or seroma, inflammation of a vein characterizes thrombophlebitis, and expansion of a blood vessel refers to an aneurysm or vasodilation. These terms do not accurately capture the essence of a hematoma, which is specifically tied to blood accumulation following vascular injury.