An excellent and brief presentation about Gangrene for medical students.

2. Gangrene
1. Overview:(Gangren–Dry,Wet /Gas)
2. Pathologic Background
3. Causes
4. Risk Factors
5. Symptoms
6. Types(Definition,Causes,Pathophysiology,Features, Morphology)
7. Difference between Dry,Wet and Gas Gangrene
8. Diagnosis
9. Treatment

3. Gangrene
Wet(Gas)
Gangrene
Bacterial
Infection
Dry
Gangrene
1.Cell/Tissue Death
(Coagulative Necrosis
+
2.Tissue Decay
(Putrefaction)

4. Changes after Cell Death
 Two types of pathologic changes
may superimpose following cell
injury:
 Gangrene (after necrosis) and
 Pathologic Calcification (after
degenerations as well as necrosis).

5. Gangrene
 Gangrene is necrosis of tissue
 associated with superadded
putrefaction.
 Most often following coagulative
necrosis due to ischaemia (e.g in
gangrene of limb and gangrene of the
bowel).

6. Causes
Arterial
Obstruction
Infection Trauma Physical Agents
Due to
• Thrombosis
• Embolus
• Diabetes
• Buerger’s
Disease
• Raynaud’s
disease
In
• Boils
• Carbuncles
In
• Crush injuries
• Pressure sores
With
• Burns
• Frostbite

7. Risk Factors
Any condition that decreases your blood
flow increases your chances of getting
gangrene, including:
 Diabetes
 Infection
 Narrowed arteries (atherosclerosis)
 Peripheral artery disease
 Smoking
 Trauma or serious injury
 Obesity
 Weakened immune system

8. Symptoms
 Skin Discoloration ,
 Numbness ,
 Skin that feels cold or cold to the touch ,
 Swelling and pain at the site of infection ,
 Fever ,
 Foul-Smelling pus leaking from a blister or sore ,
 Shiny appearance to the skin ,
 Septicemia(Blood Poisoning or Spreading of infection by blood as in Wet
Gangrene) , and
 Crepitation/Production of Crackling sound when you press on your skin (this
signals there’s a buildup of gas in your tissue in case of Gas Gangrene).

9. Types of Gangrene
There are two main types of Gangrene:
 Dry Gangrene ,
 Wet Gangrene ,
and a variant of wet gangrene called Gas Gangrene.

10. Dry Gangrene
In this type of Gangrene
 Coagulative Necrosis occur .
Main Cause
 This form of gangrene begins in the
distal part of a limb due to
Ischemia.
 The typical example is the dry
gangrene in the toes and feet of an
old patient due to severe
atherosclerosis.
Why?

11. Other Causes of Dry Gangrene
 Buerger’s disease/Thromboangiitis Obliterans(Mostly in Chronic Smokers
due to Arterial blockage in the distal areas of Arms and Legs).
 Raynaud’s disease(spasm of the arteries in the extremities, especially the
fingers and is typically brought on by constant cold or vibration).
 Trauma
 Ergot poisoning(Ergot is a chemical which causes Vasoconstriction).

12. Pathophysiology
1. Atherosclerosis due to deposition of Fat and Cholesterol
2. Narrowing of Blood Vessels
3. Decreased Blood Supply
4. Ischemia
5. Hypoxia (Deficiency of Oxygen)
6. Necrosis (Coagulative)
7. Dry Gangrene

13. Why we call it Dry Gangrene?
Proximal
Portion
Distal Portion
Gangrenous Tissue(Dry Gangrene)
Blockage in
Artery
No Blockage in Vein
Clear Line of
Demarcation between
Healthy and Gangrenous
Tissue
Features
1. Arterial Occulsion
2. Slow Infection
3. No/less Systemic infection(Transferable from one organ to other)
4. No septicemia

14. Morphology of Dry Gangrene
Grossly, affected part is
 Dry,
 Shrunken, and
 Dark black resembling the foot of a mummy.
Why Gangrenous Tissue is
black?
1. It is black due to liberation of haemoglobin from haemolysed red blood cells
which is acted upon by hydrogen disulfide (H2S) produced by bacteria
resulting in formation of black iron sulfide. The line of separation usually
brings about complete separation with eventual falling off of the gangrenous
tissue if it is not removed surgically (i.e spontaneous amputation).

15. Wet Gangrene
Wet Gangrene is naturally occur in:
 Moist tissues and organs such as Bowel,mouth,lungs,cervix and vulva.
Other Examples
To other examples of wet gangrene having clinical significance are as follows:
1. Diabetic foot which is due to high glucose content in the necrosed tissue which favours growth of bacteria.
2. Bed sores occurring in a bed ridden patient due to pressure on sites like the sacrum, buttocks and heels etc.
Main Cause
 It is mainly due to blockage of Venous flow.
Why?

16. Why we call it Wet Gangrene?
Distal Portion
Proximal
Portion
Blockage in Vein
No Clear Line of
Demarcation between
Healthy and Gangrenous
Tissue
Gangrenous Tissue
Features
1. Venous Blockage
2. Rapid Infection
3. Systemic infection(Transferable from one organ to other)
4. Septicemia
Peripheral
Arteries
Infectious
Bacteria
No Blockage in
Artery

17. Morphology of Wet Gangrene
The affected part is:
 Wet,
 Soft,
 Swollen,
 Putrid,
 Rotten, and
 Dark black.
Bowl Gangrene

18. Gas Gangrene
 It is a special form of wer gangrene.
Main Cause
 It is caused by gas-forming clostridia (gram-positive anaerobic bacteria) e.g
Clostridium perfringens .
 which gain entry into the tissues through open contaminated wounds,
especially in the muscles, or as a complication of operation on colon which
normally contains clostridia.
 They release dangerous toxins or poisons, along with gas that can be trapped in
tissue.
 Skin may become pale and gray.
Why?

19. Why we call it Gas Gangrene?
Distal Portion
Proximal
Portion
Blockage in Vein
No Clear Line of
Demarcation between
Healthy and Gangrenous
Tissue
Gangrenous Tissue
Features
1. Venous Blockage
2. Rapid Infection(e.g Clostridium Perfringens)
3. Systemic infection(Transferable from one organ to other)
4. Septicemia
5. Crepitation (due to CO2 formation).
Peripheral
Arteries
Clostridia
Perfringens
No Blockage in
Artery

20. Morphology of Gas Gangrene
The affected area is
 Swollen,
 Oedematous,.
 Painful, and
 Crepitant due to accumulation of gas bubbles of carbon dioxide within the
tissues formed by fermentation of sugars by Clostridia Perfringens.

21. Difference between Dry,Wet and Gas
Gangrene.
Features Dry Wet Gas
Blockage Arterial Venous Venous
Oedma No(Dry) Yes(Wet) Yes
Color Black Black Gray/Pale
Margines of
Gangrene
Clear Not clear Not clear
Speed of Infection Slow Rapid Rapid
Systemic Infection No Yes Yes
Septicemia No Yes Yes
Complications Less More More
Smell No Foul Foul

22. Diagnosis
To make a diagnosis,the doctor will carry out the following test:
 Blood tests to look for the presence of certain bacteria or other germs. An
abnormally elevated white blood cell counts usually indicate the presence of infection.
 Imaging tests including CT scan, X-ray, or a magnetic resonance imaging scan to view
body structures, internal organs, blood vessels or bones, and check the extent to
which the gangrene has spread.
 Fluid or tissue culture to examine for the bacterium Clostridium perfringens.
 In some cases, surgery may be performed to check the extent of spread.

23. Treatment
Treatment options may depend on the severity of your gangrene. Usually, tissues
that have been damaged by gangrene cannot be saved, but steps can be taken to
reduce the progression of your condition.
 Antibiotics that are given intravenously or taken orally.
 Surgery to remove dead tissues which may help to stop gangrene from spreading
and allows healthy tissue to heal
 If possible, damaged or diseased blood vessel may be repaired in order to increase
blood flow to the affected area.
 In severe cases, an affected body part may need to be amputated.
 Hyperbaric oxygen therapy may also be used. In this type of treatment, you are
placed in a specially designed chamber filled with oxygen at a high Pressure than
the one found in the outside air.
 The theory is that blood rich in oxygen slows the growth of bacteria and helps
infected wound heals more easily.