What does the term hematoma refer to?

The term hematoma specifically refers to a localized collection of blood outside of blood vessels, typically due to the leakage of blood from a damaged vein or artery into the surrounding tissues. This condition often arises following procedures such as venipuncture where the puncture may inadvertently damage the blood vessel walls, allowing blood to escape into the surrounding tissue.

This leads to swelling and discoloration, which can resemble a bruise, but the defining factor is the presence of pooled blood. The other options, while related to medical conditions, describe different phenomena. For example, swelling due to fluid buildup would indicate conditions like edema, and a bruise from venipuncture does not explicitly capture the leakage aspect that defines a hematoma. Additionally, a severe allergic reaction is an entirely separate medical condition and does not pertain to the context of blood leakage. Thus, hematoma is best characterized by the leakage of blood into tissues surrounding a vessel.