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Perianal abscess

What is a perianal abscess?

An abscess is a walled off collection of pus. The pus occurs due to a bacterial infection. A perianal abscess is a collection of pus around the anus.

What is the cause of a perianal abscess?

The cause is most commonly blockage and subsequent infection of one of the anal glands

What are the symptoms or a perianal abscess?

  • Constant, severe pain in or around the anus, often with an associated lump
  • Redness (erythema) around a tender area in the anal region
  • Fever (hot and/or cold chills) may be present
  • Foul-smelling discharge from within or around the anus

What investigations are required?

Examination by a your colorectal surgeon at the bedside or in the office will confirm the diagnosis. Imaging studies such as CT or ultrasound are usually not indicated for simple perianal abscesses.

Your surgeon may recommend a colonoscopy be performed at a later stage. This is to ensure there is no sinister cause for the perianal abscess. There are some inflammatory conditions that are diagnosed on colonoscopy that can result in perianal abscess, such as Crohn's disease.

What is the treatment?

The treatment is the same as that for abscesses located elsewhere on the body – surgical incision and drainage to release the pus. Due to the highly sensitive nature of the anal region, this almost always needs to be performed under general anaesthetic in the operating theatre. At the same time a close examination of the perianal region and anal canal will be performed.

Will antibiotics cure my perianal abscess?

No. Once the anal infection has caused an abscess, antibiotics will not penetrate this and will not result in resolution of the abscess. The treatment is surgical drainage. Most of the time antibiotics are not necessary once adequate drainage has occurred.

What is an anal fistula (fistula-in-ano)?

An anal fistula is an abnormal communication between the inside of the anal canal and the skin around the anus (usually where the abscess was located). A fistula can occur in up to 40% of people with a perianal abscess. A percentage of these fistulae will heal spontaneously, however over half will persist and require further surgical intervention. For more information see anal fistula.