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An anal fistula usually starts as a perianal abscess (painful swelling around back passage) which either bursts on its own or needs cutting open under anaesthetic at the hospital. Instead of healing completely you end up with a persistently discharging (and occasionally bleeding) opening a few centimetres from the anus. This is the external opening of the fistula which opens internally inside the back passage as shown above. The external opening may heal over intermittently but invariably breaks down and discharges. Antibiotics have a very limited effect. Sometimes you may have more than one opening.


  1. You may need an endoscopy (camera test) to make sure you don’t have colitis particularly Crohn’s disease which may be associated sometimes with anal fistulas.
  2. Examination Under Anaesthesia (EUA) as day case with cutting or laying open of the fistula (if superficial or just under the skin) or insertion of a thread or ‘Seton’ if the fistula runs deep through your back passage muscles. The seton helps to drain the infection and gradually makes the fistula more superficial without damaging the muscles. This can then be cut or laid open.

Occasionally your specialist may ask for an MRI scan of your pelvis to establish the exact nature and anatomy of your fistula before embarking on any treatment.

Mr Rai offers consultation and treatment for anal fistulas at the BMI Alexandra Hospital Cheadle, Spire Regency Hospital Macclesfield, 52 Alderley Road Wilmslow and the Christie Clinic.