Gangrene is the death of tissue followed by consumption by pathogens, usually bacteria. When any living tissue gets injured and if healing and repair is impossible, the tissue will die. This is known as necrosis. If the tissue is not discarded or the body cannot wall it off, bacteria will begin to consume this dead tissue and this is known as putrefaction. Gangrene is not separate from the body, but rather when the decomposing area lies adjacent or in continuity with the living tissue surrounding it, thereby running the risk of causing death to this healthy tissue.
What causes gangrene?
Causes of Gangrene
Since gangrenous areas are just putrefaction of dead tissue (necrotic tissue), the causes of gangrene are actually the pathogens like bacteria, fungi and protozoa that consume the dead material. The cause of necrosis is usually the cause of concern and this can be due to a number of factors. This may occur due to :
- Infarction – cutting off of the blood supply.
- Trauma – severe, irreparable damage to the tissue.
- Infections – certain microorganisms infect the tissue to the extent that the body is unable to combat the infection and drugs are not able to stop the degradation of the tissue.
- Diseases that cause pathological changes to tissues or organs eventually leading to cell death or an infarct.
- Chemical decomposition – either by chemicals within the body, like enzymes, or from the environment resulting in severe irreparable trauma to the tissue.
Once the tissue has died, gangrene is always a risk although on the outer areas, like the skin, death of tissue may be ‘pushed’ out and discarded spontaneously without the risk of putrefaction.
What does gangrene look like?
Signs and Symptoms of Gangrene
Prior to the onset of gangrene, death of the tissue causes certain signs and symptoms which may or may not be evident depending the area that is affected. Once gangrene sets in, there are characteristic signs and symptoms that are clearly evident. These include :
- Swelling and ulceration of the area as well as swelling and redness of surrounding living tissue.
- Offensive odor, typical of rotting flesh.
- Discoloration, ranging from dark red to purple or black.
- Loss of function of the affected area.
What are the different types of gangrene?
Types of Gangrene
Broadly, there are three types of gangrene, known as moist, dry and gas gangrene.
Moist or Wet Gangrene
In this type of gangrene, the affected tissue is swollen with fluid (edema), hence the name moist gangrene. It mainly occurs internally like in gangrene of the gut.
This type of gangrene usually occurs on a peripheral body part, like the leg, where the blood supply is totally cut off and gangrene settles in after death and drying of the tissue. Dry gangrene is commonly seen in diabetes and may also be known as diabetic gangrene.
Gas gangrene is usually caused by the Clostridium species of bacteria which invades dead or damaged tissue and causes a rapid infection of even the surrounding area. The growing bacterial population causes fermentation of the tissue which may be seen as bubbles in the fluid coming out of the affected area, hence the name gas gangrene. Gas gangrene is more commonly seen in trauma, like car accidents or war injuries, usually when soil makes contact with the open tissue.
How is gangrene treated?
Treatment of Gangrene
Antibiotics are usually needed immediately because gangrene is almost always the result of bacteria. This will prevent the spread of the infection but will not recover the dead tissue. Debridement or amputation of the affected area is imperative to prevent the decomposition from affecting healthy, living tissue. In cases of an infarction, where the blood supply to the area can be restored, this should be done immediately to prevent further tissue death and spread of the gangrene.