What describes a fluid-filled pocket that occurs due to infection?

A fluid-filled pocket that occurs due to infection is referred to as an abscess. This condition typically arises when the body's immune system tries to fight an infection, leading to the accumulation of pus, which fills a cavity. Abscesses can occur in any tissue of the body and are often localized, painful, and may be accompanied by swelling and redness in the surrounding area.

In the context of medical terminology, a fistula is an abnormal connection between two body parts, such as organs or blood vessels, which does not necessarily involve infection or fluid accumulation. A cyst is a sac-like structure that can be filled with fluid, but it is usually not caused by infection; rather, cysts can form for various reasons, such as blockage of ducts or tissue growth. Hemorrhage refers to bleeding, which involves the escape of blood from blood vessels, and does not describe a fluid-filled pocket related to infection. Hence, the significance of identifying an abscess lies in understanding its relation to infection and the body's response to combat pathogens.