When an infection causes tissue decay, the space left behind becomes a pocket of pus known as an abscess. The yellowish pus consists of bacteria, white blood cells and dead tissue. Abscess formation results from the body's attempt to contain an infection by walling off the affected area. An abscess causes pain when the associated swelling presses against nerves.

Abscesses can occur anywhere in the body. The location of an abscess determines its symptoms and severity.

HOW DOES AN ABSCESS DEVELOP?
Some abscesses develop after injuries allow bacteria to penetrate the skin. Others develop when an infection spreads from one part of the body to another through the bloodstream. An abscess can also rise as a complication of another disorder. Pneumonia, for example, can lead to a lung abscess.

WHEN SHOULD I SUSPECT AN ABSCESS?
An abscess just below the skin causes redness and swelling. Common sites of such abscesses include the anal opening, the skin alongside a fingernail and the root of a badly decayed tooth.

Abscesses may occur also internally, with symptoms varying depending on location.

IS MEDICAL ATTENTION NECESSARY?
Yes. Even a superficial abscess may need to be lanced and drained by a physician or, in the case of an abscessed tooth, a dentist. An attempt to open it yourself might cause the infection to spread. A course of antibiotics may also be required.

GETTING HELP
Call your doctor if your child:

• Has an unexplained, persistent fever

• Develops localized redness, swelling and pain in any area of the body

• Sustains a puncture injury or a deep cut that could allow bacteria to penetrate