Gangrene

Gangrene is a serious condition in which a loss of blood supply causes tissue to die.

Information written and reviewed by Certified Doctors.

Contents

Introduction

Gangrene is a serious condition in which a loss of blood supply causes tissue to die. It can affect any part of the body but typically starts in the toes, feet, fingers and hands (the extremities).

Gangrene can occur as a result of an injury, infection or a long-term condition that affects blood circulation.

Symptoms of gangrene include:

  • the affected area of tissue changes colour, such as turning red to brown to black
  • a loss of sensation in the affected area, or the area of tissue becomes extremely painful
  • the affected tissue develops black blisters and begins producing a foul-smelling pus

Read more about symptoms of gangrene.

Treatment

You should seek immediate medical advice if you think you have gangrene. The sooner the condition is treated the better the outcomes usually are.

Treatment options for gangrene include:

  • using surgery to remove damaged tissue (known as debridement)
  • using antibiotics to treat any underlying infection

In more severe cases it may be necessary to remove an entire body part such as a toe, foot, or lower leg. This is known as amputation.

Read more about the treatment of gangrene.

What causes gangrene?

Types of gangrene

The two most common types of gangrene are:

  • dry gangrene
  • wet gangrene

Dry gangrene

Dry gangrene is usually caused by a health condition disrupting the flow of blood to certain body parts; most commonly the toes and feet.

Conditions associated with dry gangrene include:

  • type 1 and type 2 diabetes – high levels of blood sugar associated with these conditions can damage the blood vessels
  • atherosclerosis – where arteries narrow and become clogged with a fatty substance known as plaque (risk factors for atherosclerosis include smoking and having high cholesterol levels)
  • peripheral arterial disease – in which a build-up of fatty deposits in the arteries restricts blood supply to leg muscles (people with diabetes, atherosclerosis and/or high cholesterol levels often go on to develop peripheral arterial disease)

Wet gangrene

Wet gangrene often occurs when a serious injury, a burn or frostbite becomes infected by bacteria.

The swelling caused by the infection can block the blood supply to the affected area which makes the infection worse.

Wet gangrene can spread much quicker than dry gangrene and can lead to further life-threatening symptoms, such as septic shock, if not treated promptly.

Other types

Other less common types of gangrene include:

  • gas gangrene – where an infection develops deep inside the body and the bacteria responsible begin releasing toxins
  • necrotising fasciitis – where bacteria spreads into the skin and then into surrounding tissue
  • internal gangrene – when blood flow to an internal organ such as the gallbladder is blocked; this often occurs as a complication of a hernia

Read more about the potential causes of gangrene.

Complications

Having an amputation – even a so-called ‘minor amputation’ such as having one of your toes or fingers removed – can have a profound negative emotional impact.

Having an entire limb removed can cause serious psychological complications. People often grieve for the loss of their limb in the same way they would grieve for the loss of a loved one. Feelings of anger and depression are common.

Read more about the complications of gangrene and recovering from the effects of an amputation.

Prevention

Many cases of dry gangrene can be prevented.

Dry gangrene usually develops inside the foot of a person with poorly controlled diabetes, atherosclerosis and/or peripheral arterial disease. If you have one of these conditions it’s important to have regular check-ups to assess the state of your feet and report any problems to your doctor as soon as possible.

A low-fat diet, regular exercise and, if you smoke, quitting smoking will also improve your blood supply.

Read more about preventing gangrene.

Who is affected

Dry gangrene is a relatively common problem among high-risk groups, such as people with diabetes and/or peripheral arterial disease, and is a common cause of amputations.

It is estimated that people with diabetes are 15 times more likely to require a major amputation than the population at large.

There is limited data about other types of gangrene which are not thought common.

Symptoms

The symptoms of gangrene can vary depending on the underlying cause.

Gangrene caused by a health condition

If the gangrene is caused by an underlying condition such as diabetes disrupting the blood supply to certain parts of the body (dry gangrene – which is the most common type of gangrene), then you will experience the following symptoms:

  • the affected body part often first turns red
  • it then becomes cold, pale and numb (though some people will experience pain)
  • without treatment the body part will begin to die – it changes colour from red to brown to black before the dead tissue then shrivels up and falls away from the surrounding healthy tissue

Gangrene caused by injury

If the gangrene is caused by a wound, burn or area of frostbite becoming infected by bacteria (wet gangrene – which progresses much faster than dry gangrene), symptoms can include:

  • swelling and redness of the affected body part
  • pain which can often be severe
  • foul-smelling discharge of pus from a sore in your skin
  • affected area will change colour – from red to brown to black

You may also experience more general symptoms related to the underlying infection, such as:

  • a high temperature (fever) of, or above, 38C (100.4F)
  • loss of appetite
  • rapid heartbeat and breathing
  • a drop in blood pressure, which can make you feel dizzy
  • shivering

If the gangrene is due to a serious skin infection (necrotising fasciitis) symptoms include:

  • redness, swelling and pain; the pain much more severe than usual in a typical skin infection
  • the affected skin becomes tense and reddened
  • the skin can change colour to purple or black
  • extensive blistering can occur and the blisters can bleed or release a dirty-looking fluid (some people have described the fluid as looking like dishwater)
  • other symptoms of sepsis such as vomiting and diarrhoea can occur due to production of toxins (poisons) from bacteria inside the body

If the gangrene is due to an infection developing inside your body (gas gangrene or internal gangrene) symptoms include:

  • a feeling of heaviness followed by severe pain
  • in most cases of gas gangrene, pressing skin near the affected area will produce a crackling sound caused by a build-up of gas; it feels like crushing fine tinfoil

When to seek help

The earlier treatment begins, the more successful it is likely to be. Contact your doctor immediately if you notice any of these symptoms:

  • skin that is cold, hard, numb and pale
  • a persistent, unexplained, severe pain
  • a persistent, unexplained fever
  • a wound that is unusually slow to heal
  • a wound that produces pus or discharge
  • a wound that produces a strong, bad smell

When to seek emergency medical advice

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 weak pulse
  • reduced urine flow
  • mental confusion
  • pale-looking skin
  • breathing difficulties
  • cold, clammy skin (in the later stages)

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

Causes

Gangrene can develop when the supply of blood to one or more areas of your body becomes blocked.

This blockage can occur in one of three ways:

  • when an underlying health condition such as diabetes causes damage to a section of blood vessels
  • infection – which in most cases is a bacterial infection
  • injury

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 lose the ability to function, and they die.

Blood contains:

  • white blood cells, which eat bacteria and then die forming pus
  • T-cells (‘T’ stands for thymus, an organ in the body which helps produce T-cells), whose job is to produce antibodies and help fight bacteria and viruses

Therefore, if the blood supply to a certain part of your body is cut, not only will tissue die but dead tissue will have a far higher risk of spreading any infection.

Gangrene and long-term conditions

Any long-term (chronic) condition that can affect your blood vessels and arteries has the potential to cause gangrene, particularly if the condition is poorly managed. These include:

  • type 1 and type 2 diabetes – high levels of blood sugar associated with these conditions can damage blood vessels
  • atherosclerosis – where arteries narrow and become clogged with a fatty substance known as plaque (risk factors for atherosclerosis include smoking and having high cholesterol levels)
  • peripheral arterial disease – in which a build-up of fatty deposits in the arteries restricts blood supply to leg muscles (people with diabetes, atherosclerosis and/or high cholesterol levels often go on to develop peripheral arterial disease)

Blood vessels are already narrow, so any damage or extra narrowing can block blood flow to a part of the body.

Diabetic foot ulcers

Gangrene often develops as a complication of an open wound or sore that develops on the skin of the feet (a diabetic foot ulcer).

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

High blood sugar associated with diabetes can damage 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 yourself without realising.

As a result, 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, restricting blood supply to your feet. Less blood means your feet will also receive a lower number of infection-fighting cells, and wounds will take longer to heal.

Reduced sensation means you are more likely to develop an ulcer, and reduced blood supply means 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 you 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). Read more about the prevention of gangrene.

Gangrene and injury

Wet gangrene often develops as a result of a traumatic injury, such as a car accident or burn. 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.

Frostbite can also lead to wet gangrene.

Gangrene and surgery

It is estimated that just under half of all 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.

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

Factors known to weaken the immune system and increase the risk of developing infection associated with gangrene include:

  • chemotherapy
  • radiotherapy
  • HIV
  • diabetes (both type 1 and type 2)
  • chronic alcohol misuse
  • injecting drugs, such as heroin
  • malnutrition – where a person’s diet does not contain sufficient nutrients to meet the demands of their body
  • being over 60 (the older you are, the less efficient your immune system is)
  • obesity – being overweight with a body mass index (BMI) of 30 or above
  • kidney failure
  • dead tissue caused by a severe injury

However, for reasons 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 and clinical tests.

Your doctor will want to find out if you have any long-term health conditions, or experienced any injuries that could have caused the condition.

They will also examine the affected area to check for any obvious signs of gangrene, such as a foul odour, or discolouration of the skin.

Clinical tests can be carried out to confirm the diagnosis of gangrene. These include:

  • Blood tests – an increase or decrease 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. This test is called a Gram stain. Bacteria are stained with a dye and examined under a microscope. The test is also useful for determining the most effective type of antibiotic to treat the infection.
  • Blood cultures – a sample of infected blood is removed and placed in a warm environment to encourage the growth of bacteria.
  • Imaging tests – a range of imaging tests, such as X-rays, MRI scans (where radio waves are used to produce an image of the inside of your body) or a computerised tomography (CT) scan can be used to confirm the presence and spread of gangrene. These tests can also be used to study blood vessels so blockages can be identified.
  • Surgery – surgical examination may be necessary to confirm a diagnosis of internal or gas gangrene.

Due to the potentially serious nature of gangrene, treatment is usually started before the results of any tests become available as delaying treatment may be dangerous.

Treatment

Treatment for gangrene involves three main objectives:

  • to remove the affected tissue with surgery (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 of gangrene, where a whole body part – such as a finger, toe, or limb – is affected, amputation may be the only viable option.

Maggot therapy ('biotherapy')

Maggot therapy is a non-surgical method of debridement.

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 fight infection by releasing substances that kill bacteria, as well as stimulating the healing process.

Maggots used for maggot therapy are specially bred in a laboratory using sterilised eggs. During maggot therapy, the tiny maggots are put on to the wound and covered with gauze, under a firm dressing. After a few days, the dressing is cut away and the maggots, often 10 times bigger after eating the dead tissue, are then flushed away.

A number of medical studies have shown 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

Serious infections are usually treated with antibiotics, which can be:

  • oral antibiotics – antibiotic tablets or capsules
  • intravenous – injected directly through your vein
  • intramuscular – injected directly into your muscles

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 bypasses 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, known as a stent, may also be inserted into the artery to help keep it open.

Research suggests that both techniques are equally effective in restoring blood flow and preventing the need for amputation. Around four out of five people who receive either type of surgery will not need 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 some forms of gangrene is hyperbaric oxygen therapy.

During this treatment you are placed in a specially designed chamber filled with pressurised air and that also contains a plastic hood filled with pure oxygen. This hood is placed over the damaged body part.

The treatment results in high levels of oxygen being dissolved in your bloodstream, leading to more oxygen being delivered to the affected areas, which speeds up healing. Hyperbaric oxygen therapy also stops damage caused by the bacteria as the oxygen 'switches off' production of toxins.

Hyperbaric oxygen therapy has proved effective in treating gangrene resulting from infected diabetic foot ulcers, reducing the 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 (skin taken from elsewhere on the body) may be used to cover the area of skin damaged by gangrene.

During a skin graft, the surgeon will remove healthy skin from another part of your body (usually a part that would be covered by clothing), and then reconnect (graft) it to the damaged area of skin.

Complications

In more severe cases of gangrene it may be necessary to amputate (cut off) a body part such as your toe, foot, or in the most serious of cases, your lower limb.

Amputation may be necessary:

  • to prevent gangrene spreading to other parts of the body
  • if the limb has been so severely damaged you can no longer use it and it is necessary to remove the limb so an artificial (prosthetic) limb can be fitted

Physical rehabilitation, where you learn to use an artificial 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. Classic symptoms of grief are often present in people who have had a limb amputated. Amputees may grieve the loss of their limb in the same way they would grieve the loss of a loved one.

Following amputation, feelings of anger and depression are to be expected and normal. However, you should contact your doctor if you are experiencing severe depression or suicidal thoughts.

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

Read more about recovering from the effects of an amputation and the possible emotional impact amputation can have.

Prevention

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

Foot care

If you have diabetes, or another long-term condition that can cause atherosclerosis (hardening or thickening of the arteries) it is important 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 prevent a diabetic foot ulcer developing:

  • Check your feet daily for problems such as numbness, discolouration, breaks in the skin, pain, or swelling. Report problems to your doctor immediately.
  • Avoid walking barefoot outside and wearing shoes without socks.
  • Do not use chemical preparations for calluses, corns or ingrown toenails. Instead, contact a podiatrist (a healthcare professional who specialises in foot care).
  • Wash your feet daily. Afterwards, make sure you dry them thoroughly, particularly between the toes. The temperature of the water used to wash your feet should be less than 37C (98.6 F).
  • 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 your feet are slightly different sizes, 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, shoes with a pointed toe, or heels higher than an inch. Shoes with 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 developing.

Smoking

Smoking can cause your arteries to become blocked, resulting in a loss of blood supply to your arms or legs.

This is known as peripheral arterial disease (PAD).

If you are committed to giving up smoking but do not want to be referred to a stop smoking service, your doctor should be able to prescribe medical treatment to help with any withdrawal symptoms you may experience.

Diet

Eating an unhealthy diet high in fat will make any existing atherosclerosis (hardening of the arteries) worse and increase your risk of developing gangrene.

Continuing to eat high-fat foods will cause more fatty plaques to build-up in your arteries. This is because fatty foods contain cholesterol.

There are two types of fat – saturated and unsaturated. Avoid foods that contain saturated fats because they increase levels of bad cholesterol in your blood.

Foods high in saturated fat include:

  • meat pies
  • sausages and fatty cuts of meat
  • butter
  • ghee (a type of butter often used in Indian cooking)
  • lard
  • cream
  • hard cheese
  • cakes and biscuits
  • food that contains coconut or palm oil

Alcohol

Drinking excessive amounts of alcohol will cause your blood pressure to rise, and also raise the level of cholesterol in your blood.

Recommended daily levels of alcohol consumption are:

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

A unit of alcohol is equal to about half a pint of normal strength lager, a small glass of wine, or a pub measure (25ml) of spirits.

Exercise

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

Unless advised otherwise by your doctor you should be aiming for at least 150 minutes of moderately intense physical exercise a week (two-and-a-half hours).

The definition of moderate intensity physical activity is any activity that increases your heart and breathing rate and may make you sweat but you are still able to hold a normal conversation.

Examples include:

  • fast walking
  • jogging
  • swimming
  • tennis
  • using a step-trainer or similar at gym

Choose physical activities you enjoy, as you are more likely to continue doing them.

It is probably unrealistic to meet these exercise targets immediately if you have not exercised much in the past.

Aim to start gradually – possibly 15 to 20 minutes of exercise five times a week – and then build on it.

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