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Anal abscess, perianal abscess and anorectal abscess

An anal abscess is a build-up of pus in the rectum and anus. This painful condition can be caused by blocked glands, sexually transmitted infections (STIs) or is connected with tearing or ulcers in the lining of the anal canal, called anal fissures.

Symptoms of anal abscess include painful or tender tissue, a lump or nodule around the anus, pus, fever, painful bowel movements, constipation and fatigue.

If an anal abscess is not fully treated or bursts, a channel can form between the end of the bowel (the anal canal and the skin near the anus, called an anal fistula.

Types of anal abscess

The most common type of abscess is a perianal abscess. This often appears as a painful boil-like  swelling near the anus. It may be red in colour and warm to the touch. Anal abscesses located in deeper tissue are less common and may be less visible.

Another type of abscess is an anorectal abscess, which occurs when pus builds up in both the rectum and anus. The rectum is the area of the large intestine where stools (faeces) are stored. This type of abscess can be caused by a  sexually transmitted infection (STI), a blocked gland or the infection of an anal fissure.

Antibiotics and surgical incision and drainage is the most common treatment for all types of anal abscesses and is usually successful.

After an abscess has been drained, however, about 40% of patients will develop a complication called a fistula. A fistula is a small channel that makes an abnormal connection between the site of the abscess and the skin.

In some cases, an anal fistula causes persistent drainage. In other cases, where the outside of the channel opening closes, the result may be recurrent anal abscesses. The only cure for an anal fistula is surgery.

Risk of anal abscess

Risk factors for anal abscesses include:

  • Inflammatory bowel syndrome (IBS) - for example ulcerative colitis, Crohn’s disease
  • Diabetes
  • Diverticulitis
  • Pelvic inflammatory disease
  • Being the receptive partner in anal sex
  • Cancer of the rectum
  • Tuberculosis (TB)
  • Chlamydia
  • Syphilis

For adults, using condoms during sexual intercourse, including during anal intercourse, can help prevent anal abscesses. For infants and toddlers, frequent nappy changes and proper cleaning during nappy changes can help prevent anal fissures and perianal abscesses.

Treatment

Anal abscesses are usually treated with antibiotics and a procedure to drain infected fluid away from the abscess.

After an anal abscess has properly healed, it's unlikely that the problem will come back. To prevent one from doing so, however, it's important to follow the advice of your doctor or bowel and rectal surgeon.

WebMD Medical Reference

Medically Reviewed by Dr Rob Hicks on December 17, 2013

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