Gangrene refers to the decay and death of tissue resulting from an interruption in blood flow to a certain area of your body. Some types of gangrene also involve a bacterial infection. Gangrene most commonly affects the extremities, including your toes, fingers and limbs, but can also occur in your muscles and internal organs.

Your chances of developing gangrene are higher if you have an underlying condition that can damage your blood vessels and impede blood flow, such as diabetes or atherosclerosis.

Treatments for gangrene include surgery to remove dead tissue, antibiotics and other approaches. The prognosis for recovery is good if gangrene is identified early and treated quickly.

When gangrene affects your skin, signs and symptoms may include:

• A blue or black discoloration of your skin
• Severe pain followed by a feeling of numbness
• A foul-smelling discharge

If you have a type of gangrene that affects tissues beneath the surface of your skin, such as gas gangrene or internal gangrene, you may notice that:

• The affected tissue is swollen and painful
• You're running a fever and feel unwell

A condition called septic shock can occur if a bacterial infection that originated in the gangrenous tissue spreads throughout your body. Signs and symptoms of septic shock include:

• Low blood pressure
• Rapid heart rate
• Lightheadedness
• Shortness of breath
• Confusion

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Gangrene of the hand and foot

Gangrene occurs when a body part — your skin, muscle or even an organ — loses its blood supply. The blood that feeds your tissues provides oxygen, nutrients to feed your cells and immune system components, such as antibodies, to ward off infections. Without a proper blood supply, your cells can't survive.

Any process that affects blood flow — an injury or an underlying condition or especially, a combination of the two — can lead to gangrene. The types of gangrene include:

• Dry gangrene. Dry gangrene is characterized by dry and shriveled skin ranging in color from brown to purplish-blue to black. Usually, dry gangrene develops slowly. It occurs most commonly in people who have a blood vessel disease, such as atherosclerosis.
• Wet gangrene. Gangrene is referred to as "wet" if there's a bacterial infection in the affected tissue. Swelling, blistering and a wet appearance are common features of wet gangrene. It can develop following a severe burn, frostbite or injury. It often occurs in people with diabetes who unknowingly injure a toe or foot. Wet gangrene needs to be treated immediately because it spreads quickly and can be fatal.

• Gas gangrene. Gas gangrene typically affects deep muscle tissue. If you have gas gangrene, the surface of your skin may initially appear normal. As the condition progresses, your skin may become pale and then evolve to a grey or purplish-red color. A bubbly appearance to your skin may become apparent, and the affected skin may make a crackling sound when you press on it because of the gas within the tissue.

  Gas gangrene is usually caused by an infection by the bacteria Clostridium perfringens, which develops in an injury or surgical wound that's depleted of blood supply. The bacterial infection produces toxins that release gas — hence the name "gas" gangrene — and cause tissue death. Like wet gangrene, gas gangrene can become life-threatening.

• Internal gangrene. Gangrene affecting one or more of your organs, most commonly your intestines, gallbladder or appendix, is called internal gangrene. This type of gangrene occurs when blood flow to an internal organ is blocked. This can occur when your intestines bulge through a weakened area of muscle in your abdomen (hernia) and become twisted. Internal gangrene often causes a fever and severe pain. Left untreated, internal gangrene can be fatal.
• Fournier's gangrene. Fournier's gangrene is an uncommon type of gangrene that involves the genital organs. Men are most often affected, but women can develop this type of gangrene as well. Fournier's gangrene usually arises due to an infection in the genital area or urinary tract and causes genital pain, tenderness, redness and swelling.

Several factors increase your risk of developing gangrene. These include:

• Age. Gangrene occurs far more often in older people.
• Diabetes. If you have diabetes, your body doesn't produce sufficient amounts of the hormone insulin (which helps your cells take up glucose) or is resistant to the effects of insulin. Diabetes along with its high blood sugar levels can eventually damage blood vessels, interrupting blood flow to a part of your body.
• Blood vessel disease. Hardened and narrowed arteries (atherosclerosis) and blood clots also can block blood flow to an area of your body.
• Severe injury or surgery. Any process that causes trauma to your skin and underlying tissue, including an injury or frostbite, increases your risk of developing gangrene, especially if you have an underlying condition that impedes blood flow to the injured area.
• Immunosuppression. If you have an infection with the human immunodeficiency virus (HIV) or if you're undergoing chemotherapy or radiation therapy, your body's ability to fight off an infection is impaired.

Gangrene is a serious condition and needs immediate treatment. Call your doctor right away if you notice any of the following signs and symptoms:

• Persistent, unexplained pain in an area of your body
• Persistent fever
• A wound that's slow to heal or recurring sores
• A foul-smelling discharge leaking from a sore
• Skin that's become pale, hard, cold and numb — which may be an indication of frostbite

Your doctor will likely ask you whether you've recently experienced any trauma, such as an injury or surgery, to the affected area of your body. You'll also talk about your medical history, including any chronic conditions, such as diabetes, which could lead to damaged blood vessels. Tests used to help make a diagnosis of gangrene include:

• Blood tests. An abnormally elevated white blood cell count often indicates the presence of an infection.

• Imaging tests. An X-ray, a computerized tomography (CT) scan or a magnetic resonance imaging (MRI) scan can be used to view interior body structures and assess the extent to which gangrene has spread.

  An arteriogram is an imaging test used to visualize your arteries. During this test, dye is injected into your bloodstream and X-ray pictures are taken to determine how well blood is flowing through your arteries. An arteriogram can help your doctor find out whether any of your arteries are blocked.

• Surgery. Surgery may be performed to determine the extent to which gangrene has spread within your body.
• Fluid or tissue culture. A culture of the fluid from a blister on your skin may be examined for the bacteria Clostridium perfringens, a common cause of gas gangrene, or your doctor may look at a tissue sample under a microscope for signs of cell death.

Gangrene can lead to scarring or the need for reconstructive surgery. Sometimes, the amount of tissue death is so extensive that a body part, such as your foot, may need to be removed.

Gangrene that is infected with bacteria can spread quickly to other organs and may be fatal if left untreated.

Tissue that has been damaged by gangrene can't be saved, but steps can be taken to prevent gangrene from progressing. These treatments include:

• Surgery. Your doctor will remove the dead tissue, which helps stop gangrene from spreading and allows healthy tissue to heal. If possible, your doctor may repair damaged or diseased blood vessels in order to increase blood flow to the affected area.

  A skin graft is a type of reconstructive surgery that may be used to treat gangrene that's caused extensive damage to your skin. During a skin graft, your doctor removes healthy skin from another part of your body — usually a place hidden by clothing — and carefully spreads it over an affected area. The healthy skin may be held in place by a dressing or by a couple of small stitches. A skin graft can only be done if an adequate blood supply has been restored to the damaged skin.

  In severe cases of gangrene, an affected body part, such as a toe, finger or limb, may need to be surgically removed (amputated). In some cases, you may be fitted with an artificial limb (prosthesis).

• Antibiotics. Antibiotics given through a vein (intravenous) may be used to treat gangrene that's become infected.

• Hyperbaric oxygen therapy. In this type of therapy, you'll be situated in a special chamber, which usually consists of a padded table that slides into a clear plastic tube. The chamber is pressurized with pure oxygen, and the pressure inside the chamber will slowly rise to about two and a half times normal atmospheric pressure.

  Hyperbaric oxygen therapy may be used to treat gas gangrene. Under increased pressure and increased oxygen content, your blood is able to carry greater amounts of oxygen. Blood rich in oxygen inhibits the growth of bacteria that thrive in the absence of oxygen and helps infected wounds heal more easily.

  Hyperbaric oxygen therapy may last anywhere from 30 minutes to two hours, and you may require more than one session. During the therapy, your ears might pop as they adjust to the increased pressure. Afterward, you may feel lightheaded and tired.

Other treatments for gangrene may include supportive care, including fluids, nutrients, and pain medication to relieve your discomfort.

Prognosis
Generally, people who have dry gangrene have the best prognoses because dry gangrene doesn't involve a bacterial infection and spreads more slowly than the other types of gangrene. However, when infected gangrene is recognized and treated quickly, the probability of recovery is good.

Older people, those who are immunocompromised, those who have underlying conditions, such as diabetes, atherosclerosis or some cancers, and those who have advanced cases of gangrene by the time that they seek treatment are most likely to suffer complications from gangrene.

Here are a few suggestions to help you reduce your risk of developing gangrene:

• Care for your diabetes. If you have diabetes, make sure you examine your hands and feet daily for cuts, sores and signs of infection, such as redness, swelling or drainage. Ask your doctor to examine your hands and feet at least once a year.
• Don't use tobacco. The chronic use of tobacco products can damage your blood vessels.
• Help prevent infections. Wash any open wounds with a mild soap and water and try to keep them clean and dry until they heal.
• Watch out when the temperature drops. Frostbitten skin can lead to gangrene, because frostbite impairs blood circulation in an affected area. If you notice that any area of your skin has become pale, hard, cold and numb after prolonged exposure to cold temperatures, call your doctor.