What is an Anorectal Abscess?

An anorectal abscess is an infected gland in the rectum that swells, fills with pus, and causes chronic discomfort. There are several mucus-filled glands along the lining of the rectum that provide lubrication during bowel movements. An anorectal abscess occurs when a cavity becomes irritated and infected with the bacteria found in stools. Without treatment, an abscess can damage anal tissue and create a large cavity, known as a fistula, that can lead to further complications. Most abscesses can be treated with relatively simple surgical procedures to drain pus and remove blockages.

Many conditions and risk factors have been associated with the development of anorectal abscesses. People who have inflammatory bowel diseases, including ulcerative colitis and Crohn's disease, are at an especially high risk due to persistent irritation and the possibility of ruptures within their rectums. Individuals with weakened immune systems due to HIV infection or another autoimmune disease are also at risk. Less commonly, a person may develop an abscess as a result of a sexually transmitted disease acquired through anal sex.

Symptoms of anorectal abscesses can vary depending on the size and location of the problem. An abscess that forms near the opening of the rectum can produce a palpable, red, swollen lump that is tender to the touch. A person may have pain during bowel movements, and blood and pus may be present in stools. Some people become constipated and develop fevers, chills, and aches. A deep anorectal abscess is less likely to cause physical symptoms, though an individual may experience slight abdominal pains and bloody stools.

A person who believes that he or she may have an anorectal abscess should visit a doctor as soon as possible to receive a proper diagnosis and learn about options for treatment. A primary care physician can usually diagnose an abscess when a lump is plainly visible, but he or she usually decides to refer a patient to a proctologist to confirm the problem. The specialist can inspect the abscess by feeling the anal cavity with a finger or inserting a small, lighted camera into the rectum. Diagnostic imaging tests may be necessary to detect deep anorectal abscesses.

Oral antibiotics may be able to temporarily relieve symptoms of an anorectal abscess, but most problems eventually require surgical procedures. A surgeon can drain the pus from an abscess by making a small incision or puncture in the affected area and drawing the pus out with a tube. Pus is collected and sent to a clinical laboratory to confirm the presence of specific bacteria, allowing doctors to prescribe the appropriate follow-up antibiotics. If an anorectal abscess creates a fistula, the surgeon may need to excise the cavity and suture the surrounding tissue. With prompt treatment and regular checkups, most patients recover within a few weeks.