Gangrene is the death of body tissue, which occurs when blood flow to a specific area is severely reduced or completely cut off. This lack of oxygen and nutrients causes the tissue to break down and die, a process called necrosis. Tissue death can also be triggered by a severe bacterial infection. Recognizing the visual signs of gangrene is important because it requires immediate medical attention to prevent the spread of tissue death and life-threatening complications. The appearance of the affected area changes dramatically depending on the specific type of gangrene involved.
The Appearance of Dry Gangrene
Dry gangrene results from a lack of blood circulation, often due to conditions like peripheral artery disease, and does not involve a bacterial infection. The affected area, commonly a toe or finger, first appears purplish-blue and then progresses to a deep brown or black. The texture of the tissue becomes dry, shrunken, and shriveled over time, often described as having a “mummified” appearance. A clear line of demarcation separates the dead, dark tissue from the surrounding healthy tissue.
When touched, the area feels cool or cold due to the lack of blood flow and may be numb, although pain can be present at the border of the living tissue. The distinguishing feature of dry gangrene is the absence of pus, discharge, or a foul odor. Since there is no active bacterial invasion, the dead tissue remains firm and does not have the moist, soft characteristics of an infected wound.
The Appearance of Wet Gangrene
Wet gangrene is characterized by a bacterial infection in the dead tissue, which causes it to be swollen and moist. The affected skin is often reddish-black or mottled, reflecting tissue death and the inflammatory response. This type is dangerous because the bacteria and their toxins spread rapidly through the moist tissue. A key visual sign is the presence of blisters (bullae) filled with fluid. These blisters often rupture, leading to the oozing of pus and discharge, giving the area its “wet” appearance.
The infected tissue is soft to the touch and severely swollen. The most distinct sign is the foul odor that comes from the affected area, produced by the bacteria as they break down the tissue. Wet gangrene needs immediate treatment because the rapid progression of the infection can lead to systemic illness and sepsis.
The Appearance of Gas Gangrene
Gas gangrene is an aggressive form of wet gangrene caused by Clostridium bacteria, which produce toxins and gas within the tissue. The skin color changes rapidly, often starting pale before quickly turning to a dusky or purplish-red and eventually bronze. Large, dark blisters containing a foul-smelling, bloody discharge are common.
A unique sign is crepitus, a crackling or crunching sensation when the affected area is pressed. This feeling is caused by the pockets of gas that the bacteria produce trapped beneath the skin. The affected area is also characterized by rapid and dramatic swelling that can progress visibly over hours. The onset is sudden and accompanied by severe pain.