An abscess is a collection of pus that has accumulated in a cavity formed by the tissue on the basis of an infectious process (usually caused by bacteria or parasites) or other foreign materials (e.g. splinters, bullet wounds, or injecting needles). It is a defensive reaction of the tissue to prevent the spread of infectious materials to other parts of the body.

Abscesses may occur in any kind of solid tissue but most frequently occur on the skin's surface (where they may be superficial pustules (boils) or deep skin abscesses). Abscesses in most parts of the body rarely heal themselves, so prompt medical attention is indicated at the first suspicion of an abscess.

How is an abscess diagnosed?

An abscess of the skin and/or subcutaneous tissue is usually diagnosed by a physical examination by your doctor. The doctor will look for signs and symptoms of an abscess, such as redness, swelling, foul smelling drainage, and sometimes fever. Abscesses that are deeper in the body may be diagnosed by radiologic tests, such as CT scans.

How are abscesses treated?

The abscess should be inspected to identify if foreign objects are a cause, which may require their removal. If foreign objects are not the cause, a doctor will usually incise and drain the abscess, prescribe painkillers, and possibly also antibiotics. Incision and drainage of skin abscesses is usually a simple procedure that can be done in the doctor's office or in an outpatient setting. Abscesses that are deeper inside the body may have to be drained in the operating room under sedation or general anesthesia. Surgical drainage of the abscess (e.g. lancing) is usually indicated once the abscess has developed from a harder serous inflammation to a softer pus stage. After drainage, an abscess cavity is often packed.