What is a Gangrene?

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Causes, Types, Symptoms, and Risk Factors

Gangrene is the death of body tissue caused by poor circulation that results from the lack of blood flow and/or severe infection by bacteria. Gangrene usually occurs in the arms and the legs, but it may also happen internally and spread throughout your body. The sooner you diagnose your gangrene and receive treatment for it, the more likely you are to recover. Finding out how to prevent gangrene is the first step to avoiding its detrimental symptoms.


These are the 3 main causes of gangrene, and they may come about due to other underlying conditions you have.

  1. Poor circulation: Firstly, a lack of good blood supply deprives your body cells of the oxygen and nutrients they need to survive. After a while, the whole tissue dies.
  1. Bacterial infection: Bacteria tend to infect untreated wounds, and they produce toxins and gas and cause the death of the tissue. This is also the main cause of gas gangrene.[1]
  1. Traumatic Injury: Severe injuries lead to deep and large wounds that allow bacteria to enter the body. If the bacteria continue to be left untreated, gangrene is likely to occur.


There are various types of gangrene, but all types have to be treated immediately to prevent deterioration to a fatal stage.

  • Dry gangrene: the type of gangrene that most commonly occurs with people who have diabetes, vascular conditions (eg. atherosclerosis) or autoimmune diseases. [2] As the name suggests, the skin will be very dry and shriveled. The skin may also appear brown, purplish-blue, or black. Dry gangrene usually  does not involve a serious infection, however, should it become seriously infected your condition will progress to become a type of wet gangrene.
  • Wet gangrene: Refers to gangrene that has associated bacterial infection. The skin tends to blister and swell, secreting pus that gives the wound a wet appearance. It tends to develop in diabetic patients when they injure themselves unknowingly due to neuropathy (numbness, inability to feel pain in certain areas). The infection from wet gangrene may spread to other parts of the body.
  • Gas gangrene: This is a type of wet gangrene that usually affects the deep muscle tissue and internal organs. As a result, you may not notice anything from the surface of your skin at first. However, as the condition gets progressively worse, your skin will eventually turn grey or purplish-red. [1] It is caused by the bacteria clostridia, which releases poison and gas that gets trapped under your skin, leading to a crackling sound when you touch your skin. Gas gangrene is very rare, but it is very deadly and can cause death in 48 hours.
  • Internal gangrene: affects your organs, like your intestines, colon, appendix and gallbladder. It occurs when blood flow to that particular organ is cut off, for example because of hernia (when organ bulges through the muscular wall) or when the intestines are twisted. [1]
  • Fournier’s gangrene: This is a gangrene of the genital area, and is the infection of either the genitals or the urinary tract. Men are affected by Fournier’s gangrene more often than women, however in general, Fournier’s gangrene is rare.


Dry gangrene

  • Shrivelled skin
  • Pain
  • Cold, hard and numb skin

Wet gangrene

  • Skin discoloration (Red, brown, purple, blue, greenish-black, or black skin)
  • A line between healthy and damaged skin
  • Blisters or sores with discharge (pus)
  • Swelling and pain
  • Fever
  • A crackling noise when you press on the skin
  • Thin, shiny, or hairless skin

If the infection spreads throughout your body, you will go into septic shock. These are the symptoms of septic shock:

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


  • Diabetes: High blood sugar levels can damage nerves, especially those in the toes or the feet. This means that diabetic patients may get injured without knowing it, leading to the wounds being neglected or left untreated. This leaves room for gangrene to develop.

The high blood sugar levels also cause arteriosclerosis (hardening and thickening of the arterial walls), obstructing blood flow and leading to poor circulation. This is also a major cause of gangrene.

Diabetes can also cause a patient to be immunocompromised and so prone to injections.

Gangrene tends to be serious in diabetic patients, so knowing how to prevent gangrene while living with diabetes is crucial.

  • Narrowed arteries (atherosclerosis): Atherosclerosis refers to the buildup of fats and other substances in the blood vessels, narrowing the lumen (opening) of the blood vessel and impeding blood flow. This therefore leads to a lack of oxygen and nutrients in certain tissues or organs.
  • Peripheral artery disease: This refers to atherosclerosis happening, which narrows the arteries as mentioned above.
  • Smoking: Carbon monoxide and nicotine from smoking encourage the buildup of fatty deposits in the arteries (atherosclerosis) and arterial walls also harden over time. All these results in poor circulation.
  • Serious frostbite: Frostbite reduces circulation in that area.
  • Obesity: Usually leads to other vascular related conditions such as diabetes and atherosclerosis that in turn cause gangrene.
  • Raynaud’s phenomenon: This refers to the narrowing of the blood vessels that supply your skin with blood. [1] Most commonly, it is the fingers that lack oxygen and begin to have gangrene.
  • Immunosuppression: Essentially this means that your immune system is weakened, and hence cannot fight infection the way it should usually be able to.

If you have any of the conditions or fall under the category of the above risk factors, please come book an appointment with the Vascular and Interventional Centre to have a consultation with our specialists, Dr. Benjamin Chua and Dr. Manish Taneja.

Contact us with the details below:

+65 6694 6270 (Call)

+65 9898 3595 (WhatsApp)

[email protected] (Email)

Novena Specialist Centre #06-08, 16-19

8 Sinaran Drive, Singapore 307470



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