By Dr Ananya Mandal, MD
Gangrene is a type of tissue death which occurs due to loss of blood supply. This may affect any part of the body but usually affects the peripheral extremities like feet, toes, fingers, hands, penis etc.
Gangrene may follow an injury or an infection or may also be a long-term condition that has caused stagnation of blood and slowed down blood circulation.
Diabetes is the commonest cause of gangrene. According to estimates from Diabetes UK, those with diabetes are fifteen times more likely to require a major amputation of a limb commonly due to gangrene compared to the general population. In the UK around 5,000 people with diabetes have an amputation as a result of gangrene annually. (1-4)
The common symptoms of gangrene include change of color of the affected area. The area first becomes red and then gets discoloured to brown and may finally become black.
There is additional loss of sensation over the area affected and this persists over the surrounding healthy skin as well. There may also be excruciating pain in some types of gangrene.
The tissues that are affected show up with black blisters and there is a foul-smelling pus beneath the thinned skin at the area.
Gangrene is of two major types - Dry and wet gangrene.
Dry gangrene occurs when there is slowing or obstruction in blood flow to parts of the body like toes and fingers.
Type 1 and type 2 diabetes mellitus leads to dry gangrene due to the high blood sugar and the damage the diabetes causes to the blood vessels that take blood to the fingers and toes.
Arteriosclerosis leads to thickened walls of the arteries or formation of cholesterol plaques and narrowing of the diameter of the small vessels leading to gangrene.
Similarly, peripheral artery disease leads to fatty deposits in the arteries and stops blood from flowing to the fingers and toes leading to gangrene.
Dry gangrene is usually limited to the part affected and there is an area of healthy skin just beyond the affected area. The area involved turns cold, dry and black and eventually falls off. This is called mummification of the area.
Wet gangrene is seen after serious injury or frost bite or even a burnt area becomes infected and the infection takes root deep into the tissues.
The infection leads to swelling of the tissues and this blocks the blood supply to the affected area making the infection worse and the gangrene progressive.
Wet gangrene can spread much quicker leading to life-threatening complications like septic shock if not treated immediately.
Gangrene may also be caused by special bacteria called Clostridium. This is called gas gangrene. This was a common infection seen during wars.
Necrotising fasciitis is caused when bacteria spreads into the skin and invades deeper tissues.
Gangrene may also affect internal organs when blood flow to them is obstructed. This is called internal gangrene and may affect the gall bladder or the intestines trapped within a hernia.
When gangrene affects the penis and the genitalia it is called Fournier’s gangrene.
Treatment of gangrene
Gangrene needs to be treated immediately on detection. The sooner the condition is treated the better the outcome and this usually means avoidance of possible amputation of the limb or fingers/toes affected with the condition to prevent spread.
Surgery is the usually first line of treatment. This type of surgery is called debridement.
Along with surgery antibiotics against the organism affecting the area are used. These may usually be administered as injections for more rapid action and may be followed up with oral antibiotic pills once the gangrene shows signs of healing.
Gangrene especially in diabetes may be prevented by adequate foot care and good blood sugar control. A healthy diet, regular exercise and stoppage of smoking may go a long way in prevention of gangrene.
Reviewed by April Cashin-Garbutt, BA Hons (Cantab)