Which term best describes a reaction to injury that results in swelling?

The term that best describes a reaction to injury resulting in swelling is edema. Edema refers to the accumulation of excess fluid in the tissues, which can occur due to various factors such as inflammation, injury, or a disruption in normal fluid balance in the body. In the context of an injury, swelling occurs as the body's response to protect the affected area, allowing more blood and immune cells to reach the site of damage.

Injuries often trigger inflammatory processes that increase vascular permeability, leading to fluid leakage into the interstitial spaces, which manifests as swelling. This swelling is not only a protective mechanism but also a part of the healing process, allowing the necessary nutrients and cells to aid in recovery.

Other terms provided relate to specific types of injury responses but do not directly describe the swelling associated with edema. For instance, bluish discoloration is typically indicative of a bruise or bleeding beneath the skin, hyphema refers specifically to blood in the anterior chamber of the eye, and ecchymosis is a form of bruising caused by bleeding into the skin or mucous membranes. These terms relate to injury responses but do not encapsulate the general concept of swelling as effectively as edema does.