What is ecchymosis?

Ecchymosis refers specifically to bruising or discoloration of the skin that results from bleeding underneath the skin's surface due to injury to blood vessels. When small blood vessels burst, they leak blood into the surrounding tissues, which causes the characteristic purplish-blue mark associated with bruises. Over time, as the body reabsorbs the leaked blood, the color of the ecchymosis changes, which is a common part of the healing process.

In contrast, the other choices describe different medical conditions: an infection of the skin implies a microbial invasion, swelling of the limb refers to edema that can occur for various reasons, and an open wound on the skin involves a break in the skin that exposes underlying tissues. Thus, ecchymosis is distinct in that it specifically indicates a type of skin discoloration related to trauma or injury.