What term refers to swelling due to excess fluid in tissues?

The term that refers to swelling due to excess fluid in tissues is "edema." Edema occurs when there is an imbalance in the fluid exchange processes between blood vessels and tissues, often resulting from factors such as increased capillary permeability, obstruction of lymphatic drainage, or changes in hydrostatic and osmotic pressures. This excess fluid accumulation is often visible and can occur in various parts of the body, such as the legs, feet, or around the eyes.

While necrosis refers to the death of cells or tissues, sometimes due to a lack of blood supply, and inflammation is an immune response to injury or infection that can also involve swelling, these terms are not specifically describing the fluid accumulation itself. A hematoma, on the other hand, is a localized collection of blood outside of blood vessels, often resulting from trauma and is not synonymous with fluid accumulation in tissues. Therefore, edema is the most accurate term to describe the swelling caused by excess fluid in tissues.