Anal fistula (‘Fistula-in-Ano’)
An anal fistula (‘fistula-in-ano’) is an abnormal connection from the skin on the outside of the back passage to inside either the anal canal or sometimes the rectum itself. An anal fistula can result from several conditions but most commonly from prior abscess around the back passage (perianal abscess), Crohn’s disease and rarely cancer.
Symptoms of a fistula-in-ano include rectal pain, feeling of fullness around the back passage or the passing of blood or pus from the rectum. If you have these symptoms, we would carefully assess you with a clinical examination and telescopic examination of the rectum (proctoscopy or rigid sigmoidoscopy). We often need to perform an endoscopic examination of the bowel with either a flexible sigmoidoscopy or colonoscopy. In addition to this, an MRI scan is sometimes required to fully assess the anatomy of the fistula to plan further treatment.
The treatment we offer for anal fistula includes an examination under anaesthetic to assess the fistula fully. Fistulas often go through the sphincter muscle that provides continence to flatus (wind) and faeces. When we assess fistulas, we carefully determine how much sphincter muscle is involved by the fistula. If the fistula involves no, or very little, sphincter muscle, we can usually lay open (cut open) the fistula, which usually cures the problem. If a lot of the muscle is involved, then cutting this sphincter can result in incontinence. In this scenario, we can place a suture or an elastic band called a seton to sit inside the fistula tract to allow drainage and prevent infection.
Some patients have more complex fistula disease. These patients need a stepwise approach to their manage often with repeated scans and operations to control the disease.