An abscess is a tender mass on a specific area of the body caused by bacterial infection. It presents as a painful swelling, pink to red in color, warm or hot to the touch. Abscesses often appear on the head and neck, limbs, torso, and are especially common in moist sites on the body such as the armpits or groin. They may also develop internally at the site of a recent operation, or, occasionally, for no apparent reason. Most often, surgical abscess drainage is necessary for successful treatment.

Types of Abscesses

Although common in parts of the body where moisture accumulates, abscesses can appear on any area of the skin or within the body. Some common types of abscesses are:

  • Dental
  • Bartholin gland, in the anus or vagina
  • Pilonoidal, at the base of the spine
  • Boil, or furuncle, around a hair follicle
  • Postsurgical abscess

Abscesses are also common in the armpits or groin.

Causes of an Abscess

An abscess may develop as a primary bacterial infection or as a complication following surgery. During an immune response, the body sends white blood cells to the area of infection. As the white blood cells attack the bacteria, the resulting inflammation and the death of nearby tissue lead to the formation of a cavity. An abscess is formed when the cavity fills with pus, a combination of dead tissue, white blood cells, and bacteria.

An abscess may also be caused by an obstruction of a sebaceous, or sweat, gland, an inflammation of a hair follicle, or a puncture or minor tear of the skin. Once germs penetrate the skin, the body's immune system attacks these germs and inflammation results. As these substances accumulate, pressure and swelling in the area result in pain.

Risk Factors for an Abscess

While abscesses may occur in any individual, they occur more frequently in individuals with poor hygiene, those who inhabit dirty environments, and those with chronic skin conditions or poor circulation. They also occur more easily in patients with weakened immune systems. Weakened immune systems may result from:

  • Underlying diseases, such as diabetes, chronic digestive disorders or cancers
  • Chronic steroid therapy
  • Chemotherapy
  • Traumatic injury
  • Substance abuse

Even in otherwise healthy, hygienic patients, some individuals are more prone to abscess development than others, either because of anatomical anomalies, a tendency to ingrown hairs, or other unknown factors.

Treatment of an Abscess

There are some situations in which an abscess will come to a head, rupture and drain without surgical intervention. In most cases, however, an abscess, unlike other infections, does not respond to antibiotic treatment alone. It usually requires an incision and drainage through needle aspiration. Frequently, the drainage procedure is performed under ultrasound or with the assistance of CT guidance. This ensures precise and effective treatment.

If an abscess is in the mouth or on the skin's surface, a local anesthetic is normally administered and a surgical incision is made at the site in order for the abscess to drain and be thoroughly cleansed of infected material. If the abscess is internal, however, an imaging test, such as an ultrasound, CT or MRI scan, may be used to locate it and define its borders. Once located, the abscess is typically drained with an aspiration needle, but, since it is likely to refill, surgery is usually necessary as well. This operation is usually performed under general anesthesia.

Fluid aspirated during the drainage procedure is sent for laboratory analysis to pinpoint the type of bacteria involved so the appropriate antibiotic can be prescribed.

Possible Complications of an Abscess

Most abscesses worsen if left untreated. The encapsulated infection can spread to surrounding tissues under the skin and eventually into the bloodstream. If the patient develops sepsis, a systemic infection that spreads through the blood, the situation becomes life-threatening. When any patient with an abscess develops a fever or becomes very ill, the situation must be treated as an emergency.

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