Gangrene

Gangrene is a term that refers to the decay and death of tissue (necrosis), caused by an interruption to blood supply. It can be a result of an injury or infection, or a complication of chronic (long-term) conditions that affect the circulation of blood.

Gangrene is a potential complication of:

• diabetes, both type 1 and type 2,
• arteriosclerosisa, a common complication of diabetes where the arteries narrow, and
• narrowing of the blood vessels that supply the skin (Raynaud's phenomenon).

Smoking is also a risk factor.

Gangrene normally affects the extremities, such as hands or feet, but can develop in the muscles and internal organs.

Treatments for gangrene include surgically removing the affected tissue, and antibiotics. In severe cases, an affected body part may need to be surgically removed (amputated).

If gangrene is detected and treated early enough, the outcome is usually favourable. The danger occurs if gangrene is accompanied by infection, and the infection spreads into the blood stream. In this case, 20-25% of people with gangrene-associated blood infection die from it.

In the UK, diabetes is the most common cause of gangrene. Every year, 5,000 people with diabetes need an amputation (limb removal) as a result of gangrene.

People with diabetes are 15 times more likely to have an amputation due to gangrene than people without diabetes.

There are several different types of gangrene, explained here:

Dry gangrene

Dry gangrene normally affects the extremities, such as your hands or feet. It occurs when one or more of your arteries become blocked. The lack of a blood supply causes the affected tissue to slowly die, but there is no infection.

The area of your body that is affected by dry gangrene usually becomes dark-coloured and cold. It will dry out and wither and eventually drop off over a period of several weeks.

Dry gangrene is common in people with chronic conditions that affect their blood supply, such as arteriosclerosis.

Wet gangrene

Wet gangrene often occurs through a combination of injury and infection. An injury, such as a burn, frostbite or a crush injury (a high degree of force or pressure, usually after being squeezed between two heavy objects), can suddenly restrict the flow of blood to tissue. Blood contains antibodies which help fight infection, so without a regular blood supply, tissue can quickly become infected by bacteria.

The swelling caused by the infection can restrict the blood supply further, which means that wet gangrene can spread quickly around the body. It is potentially life-threatening and needs immediate emergency medical treatment.

Wet gangrene often occurs in people with diabetes who injure their foot or toe.

Gas gangrene

Gas gangrene develops through infection by bacteria called clostridium, and occurs at the site of a trauma or surgical wound. The bacteria thrive in environments with little or no oxygen so it begins to produce gases while also releasing dangerous toxins. The condition is potentially life-threatening and needs immediate emergency medical treatment.

Internal gangrene

Internal gangrene can develop when blood flow to an internal organ (usually the intestine, gallbladder or appendix) is blocked. This often occurs as a complication of a hernia (when an internal part of the body, such as an organ, pushes through a weakness in the muscle or surrounding tissue wall). It is life-threatening and will need an operation.