What is a bruise?

A bruise, also known as a contusion, is a traumatic injury to the skin or the tissues underneath the skin. Bruises may occur after an accident, such as a fall, or from bumping into or being struck by a blunt object. Because the outer skin is not cut or broken, there is no external bleeding. However, damage occurs to blood vessels underneath the skin, causing them to rupture and leak blood. This blood collects or pools underneath the skin.

After a blood vessel is injured, platelets in the blood collect at the site of the injury to form a plug. The platelets combine with certain proteins called clotting factors to form a fibrin clot. This clot helps to prevent blood from leaking from the blood vessel and holds the platelets together so that healing can begin.

As the blood coagulates (clots together), the skin above the injured area will look discolored. At first, the skin is often red or purplish in color, but later on, as the bruise heals, it may turn brown, green, or yellow. This discoloration is commonly called a black-and-blue mark. Other symptoms might include swelling, tenderness, or pain in the area.

Types of bruises

The main types of bruises are:

  • Ecchymosis (plural: ecchymoses): a flat, purple-colored bruise caused when blood leaks into the top layers of the skin.
  • Hematoma: a mass of clotted or coagulated blood. It differs from a simple bruise or contusion because the area becomes swollen, raised, or painful. Hematomas may occur after an injury or impact to the skin, but they can also develop without any apparent cause. If the hematoma develops in a vital organ, the condition may become very serious and will require medical attention.

What causes bruises?

These are some of the things that can cause bruises:

  • Minor accidents, such as bumping into a piece of furniture, falling, or dropping a heavy object on your foot or hand may cause a bruise to form at the site of impact.
  • Older adults tend to bruise more easily than younger people. This is because their skin is thinner and they have less fat deposited underneath their skin to provide a cushioning effect. The blood vessels tend to break more readily after a minor injury.
  • In general, women tend to bruise more easily than men do.
  • The use of certain medications, such as anticoagulants (also known as blood thinners), can increase the tendency to bruise. Aspirin may have the same effect.
  • Certain bleeding disorders, such as hemophilia and Von Willebrand’s disease, can cause a person to bruise more easily. These conditions are caused by an absence of certain clotting factors (proteins) in the blood. Hemophilia is a relatively rare condition that is usually inherited and mostly affects males. Von Willebrand’s disease is the most common type of bleeding disorder in the United States and affects both males and females.
  • A vitamin deficiency can also result in a greater tendency to develop bruises. Vitamins B12, C and K, or folic acid play a role in the blood’s ability to clot.
  • Bruises may be a sign of domestic, child or elder abuse, especially if an individual has several bruises, or bruises keep coming back. In cases of suspected abuse, a healthcare provider or social worker may question the individual or caregiver about the cause of the injuries. The victim might need to be placed in a safe environment or the abuser might have to be removed from the home to prevent further harm to the person.