What is a hematoma?

A hematoma is indeed defined as a mass of clotted blood that occurs outside of blood vessels, typically resulting from a rupture or leakage of blood from vessels due to injury or trauma. When a vessel breaks, blood seeps out into surrounding tissues, causing swelling and discoloration, which is what we commonly recognize as a bruise. This accumulation of blood can create pressure and discomfort in the affected area, and over time, the body will gradually reabsorb this blood, causing the hematoma to resolve.

The other options highlight different medical conditions that do not describe a hematoma. For instance, a swelling of water due to dehydration does not accurately reflect the nature of a hematoma, which specifically involves blood. Similarly, a benign tumor in the organs pertains to a growth rather than a collection of blood, and blood poisoning relates to infections in the bloodstream, which is also distinct from the concept of a hematoma.