What are abscesses?

Quick Answer
Any enclosed collection of pus, whether sterile or infected.
Expert Answers
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Causes and Symptoms

When bacteria enter the body’s tissue, white blood cells migrate to the site to fight infection. As they fight off the bacteria, they subsequently die. These dead white blood cells, and the enzymes that they produce as they decay, accumulate as fluid. It is this fluid that forms what is commonly known as pus. An enclosed collection of pus is called an abscess. Abscesses may occur at various sites within the body. Because bacteria often enter the body through the skin, abscesses commonly occur at sites just under the skin. Perhaps the most common abscesses are staph infections, which are caused by the bacterium Staphylococcus aureus.

Abscesses can occur in the abdomen, pelvis, kidneys, spleen, pancreas, liver, or prostate gland, or in the area behind the abdominal cavity (the retroperitoneal space). Abscesses can also occur in the head, neck, or hands, or in any of the muscles throughout the body. Throat abscesses are more likely to develop in children than in adults, often as a result of an infection such as strep throat. Though most commonly under the skin, where they are readily discernible, abscesses can also form deep within the body, where they are undetectable unless a diagnostic procedure such as computed tomography> (CT) scanning or magnetic resonance imaging (MRI) is used. Signs aiding in the diagnosis of an abscess include heat, swelling, tenderness, and redness at the site. Bodywide, or systemic, symptoms such as fever or weight loss can also accompany abscesses, often when they are deeper.

Because people with weakened immune systems have a decreased ability to ward off infection, they are more likely to develop abscesses than are people with healthy immune systems. Abscess formation is frequently seen in patients with diabetes, sickle cell disease, and Acquired immunodeficiency syndrome (AIDS), or in patients on steroid therapy.

Abscesses can foster processes that infect the blood, causing sepsis, which can spread infection to distant sites within the body. A locally spread abscess can cause bleeding in nearby vessels or impair the functioning of a major organ.

Treatment and Therapy

Patients often will not seek medical attention for an abscess until it has become painful or inconvenient. The abscess may come to a point, or “head,” and rupture spontaneously. If the abscess does not rupture, then it may require drainage. The site is numbed with an anesthetic; the abscess is cut open and drained. The pus is manually expressed. When the abscess is large enough, packing may be inserted to minimize bleeding and to help prevent the reaccumulation of pus. The packing is often removed the following day. Usually, antibiotics are not needed, but they may be prescribed to prevent reinfection. Deep abscesses sometimes require CT-guided drainage. Analyzing the pus in a laboratory can often help to guide treatment.

Prompt treatment of infections will often prevent the development of abscesses. Patients should be instructed to take care of injuries of any type, particularly bites and puncture wounds. The prognosis after treatment is good, as most abscesses should heal well.


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