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Gangrene

Gangrene is a serious and often life-threatening condition where the body’s tissue begins to decay and die as a result of an interruption in the blood supply.

Gangrene can occur as a result of:

• injury
• infection
• a chronic (long-term) condition that affects blood circulation

Conditions where gangrene is a potential complication include:

• type 1 and type 2 diabetes
• arteriosclerosis, where the arteries narrow
• Raynaud's phenomenon, narrowing of the blood vessels that supply the skin

Smoking also increases your risk of developing gangrene.

Types of gangrene

There are several different types of gangrene:

Dry gangrene

Dry gangrene usually affects the body’s extremities, such as the hands or feet. It occurs when one or more of your arteries become blocked. The lack of 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 looks darker and feels cold. Over several weeks the body part will dry out and wither, before eventually dropping off.

Dry gangrene is common in people who have chronic (long-term) 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 (where the body is subjected to 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 that fight infection, so without a regular blood supply, tissue can quickly become infected by bacteria.

The swelling that is caused by the infection can further restrict the blood supply, which means that wet gangrene can spread quickly around the body. The condition is potentially life-threatening and needs immediate emergency medical treatment. Wet gangrene often occurs in people who have diabetes, following an injury to their foot or toe.

Necrotising fasciitis

Necrotising fasciitis is a form of gangrene that spreads quickly and is caused by a serious bacterial infection. Necrotising fasciitis is sometimes referred to as flesh-eating bacteria.

It occurs when bacteria enter a cut in the skin and quickly spread, releasing harmful toxins (poisons). These block the supply of blood to surrounding skin tissue, causing it to die.

Necrotising fasciitis usually affects people who have seriously weakened immune systems (immunocompromised). However, for reasons that are unclear, cases have also been reported in previously fit and healthy people.

Gas gangrene

Gas gangrene is similar to necrotising fasciitis, but the infection develops deeper inside the body, such as inside the muscles, usually as the result of a trauma or a surgical wound.

The bacteria responsible for gas gangrene (clostridium) thrives in environments where there is little or no oxygen (anaerobic). It begins to produce gases, while also releasing dangerous toxins. Like necrotising fasciitis, gas gangrene can be life-threatening and requires emergency medical treatment.

Internal gangrene

Internal gangrene can develop when the 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). Internal gangrene is life-threatening and requires surgery.

How common is gangrene?

In England, dry gangrene is the most common type of gangrene and mainly affects people with diabetes. Every year, 5,000 people with diabetes have an amputation (where part of the body is cut off) as a result of gangrene.

People with diabetes are 15 times more likely to have an amputation as a result of gangrene compared with people who do not have diabetes.

There is limited data about other types of gangrene because as they tend to occur as complications of emergency medical conditions, they are not recorded in the same way. However, occurrences of other types of gangrene are thought to be rare. For example, each year in the UK, it is estimated that there are 500 cases of necrotising fasciitis.

Outlook

If dry gangrene is detected and treated early enough, the outcome is usually favourable.

The outlook for wet gangrene, gas gangrene, and necrotising fasciitis is less favourable. This is because they are caused by infection, and bacteria often spreads into the blood (sepsis) which, in turn, can lead to multiple organ failure and a massive drop in blood pressure (septic shock).

It is estimated that 20-25% of people with a gangrene-associated blood infection die of the condition.

The outlook for internal gangrene is highly variable, depending on how quickly the condition is diagnosed and treated.

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

Symptoms

Dry gangrene

The symptoms of dry gangrene normally begin with a red line on the skin that marks the edges of the affected tissue. The area will become cold and numb. As the tissue dies, you may experience some pain. However, many people, particularly the elderly, experience no sensations. The affected area of tissue will change colour from red, to brown, to black. The dead tissue will then shrivel up, separate from the healthy tissue and fall off.

Wet gangrene

The symptoms of wet gangrene begin with the affected area swelling, before the tissue starts to decay. Unlike dry gangrene, the condition is extremely painful. If you have wet gangrene, your skin will change colour, from red, to brown, to black, and produce foul-smelling pus. Other symptoms such as a high temperature (fever) of, or above, 38C (100.4F) are also common.

Necrotising fasciitis

Necrotising fasciitis can affect any part of the body, although most cases develop in the extremities, such as:

• the hands, arms, feet  and legs
• the perineum, which is the area of skin between the anus and the genitals
• the torso, which is the central part of the body between the neck and the limbs

Initial symptoms of necrotising fasciitis usually include swelling, redness, and pain. The pain is often more than what you would expect for a typical skin infection.

As the infection progresses, the skin becomes increasingly tense and red, with noticeable margins between the affected and unaffected skin.

Over the course of several hours or, in some cases, days, the symptoms of necrotising fasciitis will rapidly worsen. The skin will change colour to purple or black, severe blistering will develop and the affected skin may make a crackling noise.

The blisters may begin to bleed and some people may experience a discharge of fluid (often described as looking like dishwater) from the affected area.

Gas and internal gangrene

Both gas and internal gangrene have similar symptoms. People who have had these types of gangrene have talked about experiencing a feeling of heaviness in the affected area, followed by severe pain. The pain is a result of swelling caused by the gas or infection.

In the majority of cases of gas gangrene, pressing the skin near the affected area will produce a crackling sound. This is caused by the gas that is produced by the bacteria.

In some cases of gas gangrene, there may be a watery discharge from the affected area. However, unlike wet gangrene, the discharge does not have a distinctive foul odour.

Septic shock

If bacteria from gangrene pass into your bloodstream, you could go into septic shock. This is a condition where bacteria multiply in the blood, releasing toxins that damage cells and organs, dramatically lowering your blood pressure.

Signs of septic shock include:

• a rapid but very weak pulse
• reduced urine flow
• confusion
• pallor (pale-looking skin)
• cold, clammy skin (only in later stages)
• collapse

When to seek emergency medical advice

Septic shock is the most serious complication that can arise from gangrene. See above for the symptoms of septic shock.

If you suspect that you, or someone you know, has septic shock, dial 999 to request an ambulance immediately.

Causes

The role of blood

Blood contains two important components that the body’s cells require for life:

• oxygen
• nutrients, such as glucose, amino acids, and fatty acids

Without an uninterrupted supply of oxygen and nutrients, the body’s cells will lose the ability to function and they will die.

Blood also contains white blood cells and T-cells (‘T’ stands for thymus, an organ in the body which helps to produce T-cells), both of which the body uses to help fight bacteria and viruses. Therefore, if the blood supply to a certain part of your body is cut off, not only will the tissue die but the dead tissue will have a far higher risk of becoming infected.

Gangrene and chronic disease

Any chronic (long-term) condition that can affect your blood vessels and arteries has the potential to cause gangrene, particularly if the condition is poorly managed. The blood vessels are already very narrow, so any damage or extra narrowing of the vessels can block the flow of blood to a part of the body.

Diabetic foot ulcers

Diabetic foot ulcers (an open wound or sore that develops on the skin) are one of the major causes of gangrene and amputation in people with diabetes. If you have diabetes, you may be more at risk of developing foot ulcers as a result of:

• reduced sensation
• reduced blood supply

These are described in more detail below.

Reduced sensation

The high blood sugar that is associated with diabetes can cause damage to the nerves (peripheral neuropathy), particularly in your feet. Once damaged, the nerves are unable to transmit sensations of pain to your brain.

Therefore it is easy to damage or injure your foot by treading on something sharp, or to develop a blister due to ill-fitting shoes without actually realising it. As a result of the lack of pain, you may continue walking without protecting the wound. This can make the wound worse and it may develop into an ulcer.

Reduced blood supply

High blood sugar can damage your blood vessels, causing the blood supply to your feet to become restricted. If the skin on your feet receives less blood, it will also receives a lower number of infection-fighting cells, which means that wounds will take longer to heal.

Therefore, the reduced sensation means that you are more likely to develop an ulcer, and the reduced blood supply means that the ulcer is more likely to become infected. The infection is likely to restrict the blood supply further, leading to gangrene.

If you have type 1, or type 2, diabetes, it is essential that you to take extra care of your feet. You should get your feet checked regularly by a podiatrist (a medical professional, also known as a chiropodist, who specialises in foot care). See Gangrene - prevention for more information about this.

Gangrene and injury

Wet gangrene often develops as a result of a traumatic injury. The injury causes a sudden loss of blood to an area of your body, causing the tissue in that area to become infected with bacteria. It is estimated that around 50% of cases of wet gangrene are caused by serious traumatic injuries.

Common causes of wet gangrene can include:

• car accidents
• industrial accidents
• crush injuries
• burns

Gunshot wounds and frostbite are also causes of wet gangrene, but they are less common.

Gangrene and surgery

It is estimated that 40% of wet gangrene cases occur as a result of infection that develops during surgery. However, due to advances in surgical techniques and infection control, the chances of gangrene developing during surgery are very rare.

Gangrene and infection

Gangrene that results from infection, such as gas gangrene, or necrotising fasciitis, is very rare because the immune system usually prevents the spread of any harmful bacteria that may enter your body through a cut or other type of wound.

However, if your immune system is seriously weakened, minor infections may turn into serious infections. This can lead to gangrene developing.

Factors that are known to weaken the immune system, and increase the risk of developing infection that is associated gangrene include:

• chemotherapy
• radiotherapy
• HIV
• diabetes (both type 1 and type 2)
• chronic alcohol misuse
• intravenous drug abuse (injecting drugs, such as heroin)
• malnutrition
• being over 60 (the older you are, the less efficient your immune system is)
• obesity
• kidney failure

However, for reasons that are still uncertain, a significant number of cases of necrotising fasciitis occur in young and otherwise healthy people.

Diagnosis

Diagnosis of gangrene is based on a combination of

• physical examination
• medical history
• clinical tests

Your GP will want to know if you have any chronic health conditions and whether you have experienced any injuries that could have caused the condition.

They will also examine the affected area of your body to check for any obvious signs of gangrene, such as a strong smell or strange colour of the skin.

Clinical tests can be carried out to confirm the gangrene diagnosis. They are:

• Blood tests. An increase in the number of white blood cells can indicate infection.
• Fluid or tissue culture. A small sample of fluid or tissue from the affected area can be tested for bacteria. The test is also useful for determining the most effective type of antibiotic to treat infection.
• Imaging tests. A range of imaging tests, such as X-rays, MRI scans or CT scans (where a series of X-rays are taken, to build up a three-dimensional picture of your body), can be used to confirm the presence, and spread, of gangrene. These tests can also be used to study the blood vessels, so that any blockages can be identified.
• Surgery. A surgical examination may be necessary to confirm a diagnosis of internal or gas gangrene.

Treatment

Your treatment plan

Treatment for gangrene involves three main objectives:

• to remove the affected tissue (debridement)
• to prevent infection (or if infection is already present, to prevent it spreading)
• to address the conditions that led to gangrene developing

For example, if gangrene is caused by a poor blood supply, surgery may be used to repair damaged blood vessels. This is known as vascular surgery.

Debridement

Debridement is the surgical removal of the dead tissue that results from gangrene. Removing the dead tissue will prevent the gangrene from spreading and allow healthy tissue to heal.

In severe cases, where a whole body part such as a finger, toe, or limb is affected, amputation may be the only viable option.

Maggot therapy

Maggot therapy is a non-surgical method of debridement. Maggots have been used to treat wounds for a long time, and during the First World War they became a popular method of cleaning wounds.

Certain types of maggot (those from fly larvae) are ideal for debridement because they feed on dead and infected tissue, but leave healthy tissue alone. They also help to fight infection by releasing substances that kill bacteria, as well as stimulating the healing process.

Maggots that are used for maggot therapy are specially bred in a laboratory using sterilised eggs. During maggot therapy, the maggots are mixed into a wound dressing, and the area is covered with gauze. After a few days, the dressing is cut away and the maggots, which are often 10 times bigger after eating the dead tissue, are then flushed away.

A number of medical studies have shown that maggot therapy can achieve more effective results than surgical debridement. However, due to the nature of this type of treatment, many patients are reluctant to try it.

Infection

Infections are usually treated with antibiotics, either intravenously (injected directly through your vein) or intramuscularly (injected directly into your muscles). In order to counter the effects of infection, and accelerate the healing process, you will also require intravenous fluids and nutrients and, in some instances, blood transfusions.

Vascular surgery

There are two main ways that surgery can be used to restore blood flow. These are described below.

• Bypass surgery, where the surgeon redirects the flow of blood and by-passes the blockage by connecting (grafting) one of your veins to a healthy part of an artery.
• Angioplasty, where a tiny balloon is placed into a narrow, or blocked, artery, and is inflated to open up the vessel. A small metal tube (a stent) may also be inserted into the artery to help keep it open.

Research suggests that both of these techniques are equally effective in restoring blood flow and preventing the need for amputation. Around 80% of people who receive either type of surgery will not need to have an amputation.

An angioplasty has the advantage of having a faster recovery time than bypass surgery, although it may not be as effective in the long-term as bypass surgery.

Hyperbaric oxygen therapy

An alternative treatment for gangrene is hyperbaric oxygen therapy. During this treatment, you are placed in a specially designed chamber, which is similar to the decompression chambers that are used by deep-sea divers to avoid decompression sickness (the bends).

The chamber is filled with oxygen, which is administered at a much higher pressure (hyperbaric) than the normal level of oxygen in the atmosphere.

This results in high levels of oxygen being dissolved into the blood stream, leading to more oxygen being delivered to the gangrenous areas, which speeds up healing. Hyperbaric oxygen therapy also halts and reduces the spread of bacteria because they cannot thrive in an oxygen-rich atmosphere.

Hyperbaric oxygen therapy has proved to be effective in treating gangrene that results from infected diabetic foot ulcers. The treatment helps to reduce a person’s risk of amputation.

Evidence relating to the effectiveness of hyperbaric oxygen therapy in treating other types of gangrene is limited, and further research is required.

Reconstructive surgery

Reconstructive surgery using a skin graft may be a possible way of treating gangrene that has caused damage to your skin.

During a skin graft, the surgeon will remove healthy skin from another part of your body (usually a part that is normally under clothing and not seen), and they will then reconnect it (graft it) to the damaged area of skin.

Complications

Amputation

For the majority of people, having a body part amputated (cut off) is a traumatic experience. Physical rehabilitation, where you learn to use an artificial or prosthetic limb, can be a long and gruelling process. It will often take a year or more of rehabilitation and physiotherapy before you become used to using your limb(s) for everyday activities.

Amputation can also have serious psychological complications. The classic symptoms of grief are often present in people who have had a limb amputated. People often grieve for the loss of their limb in the same way that they would grieve for the loss of a loved one.

Following amputation, feelings of anger and depression are a normal part of the grieving process. However, you should contact your GP if you are constantly feeling sad, or if you are having suicidal thoughts.

If you have had a part of your body amputated, you will be offered counselling. Many people who have had limbs removed have said that becoming involved with support groups and self-help groups has helped them to come to terms with their condition.

The UK Limb Loss Information Centre provides a range of information, resources, and support for people who have had a limb amputated.

Prevention

There are a number of self-care techniques that can help to lower your risk of developing gangrene. These are explained below.

Foot care

If you have diabetes or another chronic condition that can cause arteriosclerosis (hardening or thickening of the arteries), it is important that you take extra care of your feet.

If you have diabetes, you should have your feet checked at least once a year. However, more frequent check-ups may be required for those who have additional risk factors, such as peripheral neuropathy (lack of feeling, or numbness, in the hands and feet) or a history of previous foot ulcers.

The advice listed below can help you to prevent developing a diabetic foot ulcer.

• Check your feet daily for any problems, such as numbness, discolouration, breaks in the skin, pain or swelling. Report any problems to your GP immediately.
• Avoid walking barefoot outside and wearing shoes without socks.
• Do not use chemical preparations for calluses, corns, or in-growing toenails. Instead, you should contact a podiatrist (a healthcare professional who specialises in foot care).
• Wash your feet daily. Afterwards, make sure that you dry them thoroughly, particularly between the toes. The temperature of the water that you use to wash your feet should be less than 37C (98.6F).
• Avoid using hot water bottles, electric blankets, foot spas and sitting too close to the fire. These may burn your feet, particularly if you have reduced sensation. Burnt tissue is vulnerable to gangrene.
• Have your feet measured properly. If there is a difference between the size of your feet, you should buy shoes to fit the larger foot. Your podiatrist may be able to provide you with specially made-to-measure "diabetic footwear" or they may be able to recommend a stockist.
• Avoid wearing sandals, flip-flops, slip-ons and shoes that have a pointed toe, or heels that are higher than an inch. Shoes that have round or square toes, and laces or fasteners, provide the best support and protection for your feet. Always break new shoes in gradually.

If you have a history of foot ulcers, wearing specially designed therapeutic or orthopaedic shoes can help prevent further ulcers.

Smoking

The damage that is caused by cigarette smoke can cause your arteries to become blocked, resulting in a loss of blood supply to your arms or legs and leading to the development of gangrene.

This is known as peripheral vascular disease (PVD). In the UK, around 2,000 smokers a year have an amputation as a result.

If you decide to stop smoking, your GP will be able to refer you to an NHS Stop Smoking Service, which will provide you with dedicated help and advice about the best ways for you to give up smoking. You can also call the NHS Smoking helpline on 0800 022 4 332. The trained helpline staff will be able to offer you free expert advice and encouragement.

If you are committed to giving up smoking, but do not want to be referred to a stop-smoking service, your GP should be able to prescribe you medical treatment to help with any withdrawal symptoms that you may experience after quitting. See Smoking - treatment for more information as well as the stop-smoking section of Live Well.

Take regular exercise

A healthy, well-balanced diet and regular exercise will help to keep your blood pressure and cholesterol levels at recommended levels, helping to prevent your blood vessels becoming damaged.

A minimum of 30 minutes of vigorous exercise a day, at least five times a week, is recommended. The exercise should be strenuous enough to leave your heart beating faster and you should feel slightly out of breath afterwards. Vigorous exercise includes going for a brisk walk and walking up a hill.

More information about fitness and exercise is also available on the Live Well section of the website.

Diet

For good all-round health, a low-fat, high-fibre diet is recommended that includes wholegrains and plenty of fresh fruit and vegetables (at least five portions a day).

You should limit the amount of salt that you eat to no more than 6g (0.2oz) a day, because too much salt will increase your blood pressure. One teaspoonful of salt is equal to about 6g.

You should avoid eating foods that are high in saturated fat because this will increase your cholesterol level. Foods that are high in saturated fat include:

• meat pies
• sausages and fatty cuts of meat
• butter
• ghee, a type of butter that is often used in Indian cooking
• lard
• cream
• hard cheese
• cakes and biscuits
• foods that contain coconut, or palm oil

Eating some foods that are high in unsaturated fat can help to decrease your cholesterol level. Foods that are high in unsaturated fat include:

• oily fish
• avocados
• nuts and seeds
• sunflower
• rapeseed
• olive oil

See healthy eating (Live Well) for more information and advice about eating healthily.

Alcohol

Drinking too much alcohol will cause your blood pressure to rise, as well as raising the cholesterol levels in your blood.

The recommended daily levels of alcohol consumption are:

• three to four units for men
• two to three units for women

One unit of alcohol is equal to one of the following: 

• half a pint of normal-strength lager
• a small glass of wine 
• a pub measure (25ml) of spirits.

For more information, see the alcohol section on Live Well.

Lose weight

There are many benefits that are associated with losing weight. If you can reach the ideal weight for your height, it will help lower your cholesterol levels and your blood pressure.

The most successful weight loss programmes include at least 30 minutes of daily exercise, eating smaller portions and only having healthy snacks in between meals. A gradual weight loss of around 0.5kg (1.1lbs) a week is usually recommended.

Also see Obesity - treatment and lose weight (Live Well).