A bruise is sensitive to touch. Bleeding is often visible as a bruise on the skin. Over time, it turns a greenish-yellow color. After a few days to weeks, the area heals. If the bleeding is deeper (subcutaneous bleeding), you will not see any discoloration, but you will see swelling. After a few days, blue discoloration may still appear. Sometimes these are not at the site of the original injury.
The cause of bruising is usually external force. You bump into something or fall. Broken bones or surgery also often cause bruising. In all cases, bruising occurs in the blood vessels, causing blood to leak into the surrounding tissue. This can happen just under the skin, but it can also happen deeper. The body breaks down and reabsorbs this blood. Hemoglobin is also broken down in this process. This is converted into yellow pigments. This causes the color of the bruise to change over time.
