What is a hematoma?

A hematoma is characterized as a raised, ecchymotic area that occurs when blood leaks out of the vessel into the surrounding tissue, typically as a result of trauma or injury to the blood vessel. This leakage leads to a localized collection of blood outside of the vessel, which produces visible discoloration and swelling in the affected area. The term "ecchymotic" refers to the bruising that occurs as a result of this accumulation, making option B the most accurate description of a hematoma.

In contrast, a solid mass in the vein typically indicates a different condition, such as a thrombosis or clot formation, not a hematoma. Fluid accumulation around the catheter specifically refers to another phenomenon, such as infiltration or extravasation, where intravenous fluids leak into the surrounding tissue, rather than a hematoma. Lastly, an infection in the vein, known as phlebitis or thrombophlebitis, does not describe the definition of a hematoma, which is strictly related to the accumulation of blood outside of the vascular system.