Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.
Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.
Gangrene is a term that describes dead or dying body tissue(s) that occur
because the local blood supply to the tissue is either lost or is inadequate to
keep the tissue alive. Gangrene has been recognized as a localized area of
tissue death since ancient times. The Greeks used the term gangraina to describe putrefaction (death) of tissue. Although many laypeople associate the term gangrene with a bacterial infection, the medical use of the term includes any cause that compromises the blood supply that results in tissue death. Consequently, a person can be diagnosed with gangrene but does not have to be "infected."
There are two major types of gangrene, referred to as dry and wet. Many cases of dry gangrene are not infected. All cases of wet gangrene are considered to be infected, almost always by bacteria. The most common sites for both wet and dry gangrene to occur are the digits (fingers and toes) and other extremities (hands, arms, feet, and legs).
What is the difference between wet and dry gangrene?
Wet (also sometimes termed "moist") gangrene is the most dangerous type of gangrene because if it is left untreated, the patient usually develops sepsis and dies within a few hours or days. Wet gangrene results from an untreated (or inadequately treated) infection in the body where the local blood supply has been reduced or stopped by tissue swelling, gas production in tissue, bacterial toxins, or all of these factors in combination. Additionally, conditions that compromise the blood flow such as burns or vascular trauma
(for example, a knife wound that cuts off arterial flow) can occur first. Then the locally compromised area becomes infected, which can result in wet gangrene. Wet gangrene is the type that is most commonly thought of when the term gangrene is used. Wet gangrene often produces an oozing fluid or pus, hence the term "wet." Early stages of wet gangrene may include signs of infection, aching pain with swelling, a reddish skin color or blanched appearance if the area is raised above level of the heart, coolness on the skin surface, ulceration, and a crackly sensation when the skin is pressed due to gas in the tissue. These stages may progress rapidly over hours to days.
Dry gangrene, if it does not become infected and progress to wet gangrene, usually does not cause sepsis or cause the patient to die. However, it can result in local tissue death with the tissue eventually being sloughed off. Usually, the progression of dry gangrene is
much slower (days to months) than wet gangrene because the vascular compromise slowly develops due to the progression of diseases that can result in local arterial blockage over time. The stages are similar to wet gangrene (see above), except there is no infection, pus, wetness, or crackly-feeling skin because there is no gas production in the uninfected tissue. There are many diseases that may lead to dry gangrene; the most common are diabetes, arteriosclerosis, and tobacco addiction (smoking). Infrequently, dry gangrene can occur quickly, over a few hours to days, when a rapid arterial blockage occurs (for
example, an arterial blood clot suddenly occludes a small artery to a toe). Dry gangrene often produces cool, dry, and discolored appendages (sometimes termed "mummified") with no oozing fluid or pus, hence the term "dry."
Reviewed by Melissa Conrad Stöppler, MD on 10/2/2012
You may notice the following symptoms at the site of the dry gangrene:
dry and shriveled skin that changes color from blue to black and eventually sloughs off
cold and numb skin
pain may or may not be present
Symptoms of wet gangrene may include:
swelling and pain at the site of infection
change in skin color from red to brown to black
blisters or sores that produce a bad-smelling discharge (pus)
fever and feeling unwell
a crackling noise that comes from the affected area when pressed
Internal gangrene usually has pain in the area of the gangrene. For example, a person with gangrene of the appendix or colon would be expected to have severe abdominal pain in the vicinity of the gangrene.