Abscesses and anal fistula

An abscess is a collection of pus – rather like a boil.

Abscesses that occur around the anal area probably result from infection of a small gland, which is one of many that may encircle the lower part of the anal canal.

The pus builds up in the tissues around the anal canal and then tends to present as a painful lump around the anal area.

If the abscess bursts, then there is likely to be a communication between the lower part of the anal canal and the skin beside the anus, and such an abnormal communication is referred to as a fistula.

What is anal fistula?

It is an abnormal connection between the internal lining of the anus and the skin outside the anus. Most fistulae are the result of infections in an anal gland but may be related to inflammatory bowel disease such as Crohn’s Disease or ulcerative colitis.

Surgery is almost always needed to cure a fistula. The types of surgery can vary:

Fistulotomy opens the length of the fistula, allowing the open wound to heal. Some of the sphincter muscle is divided.

Seton management involves a loop of flexible material being placed along a fistula track, which slowly opens the length of the track, minimising the risk of impaired anal control.

Fistula repair closes the fistula track, but is a complex procedure, which is not always successful.

Management and treatment

Abscesses generally will not be cured by antibiotics and do require drainage (“incising”). Drainage can sometimes take place as an office procedure, but in most instances will require proper anaesthesia in an operating room.

An abscess may well recur if the underlying fistula track is not located and laid open. Often this track can be laid open at the time that the abscess is drained, but sometimes infection prevents the surgeon from identifying it. Under such circumstances when all the infection has settled, it may be appropriate to have a further procedure done at an elective date to identify the fistula track, lay it open and thus prevent further problems.

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