What is an anal fistula?
An anal fistula is a communication between the skin around the anus and the anal canal. This communication crosses the anal sphincter muscle.
What are the symptoms of an anal fistula?
There is a small opening near the anus that discharges pus and blood. If the opening heals over there will be a buildup of infection till it discharges again. It will be painful if there is a buildup of pus but generally a fistula does not cause much pain. There can be more than one fistula.
What causes anal fistula?
Most fistulae are due to infections in the glands that surround the anal canal. These glands open into the anal canal and get blocked causing an abscess that then opens onto the skin. The abscess presents as a painful lump and either drains spontaneously or is surgically drained. The result is a communication from where the abscess drained on the skin into the anal canal where the gland usually opens.
Most patients have no obvious cause for the abscess and fistula. Occasionally fistulae can develop due to underlying conditions such as Crohn’s disease.
What investigations are required?
Investigations are required to determine how much of the sphincter muscle is involved by the communication (tract). Ultrasound, MRI and examination under anaesthesia are used.
What treatment is required?
All fistulae require surgery. They will very rarely spontaneously close but will frequently be a recurrent problem.
The treatment depends on how much of the sphincter is involved. Sometimes several operations are required. The risk relates to damage of the sphincter muscle and possible faecal incontinence.
All the procedures are performed under general anaesthesia and are mostly simple day cases.