Anal Fistula: Causes, Symptoms and Surgical Repair

An anal fistula is a small tunnel that develops between the inside of the anal canal and the skin nearby. It usually needs surgery to resolve.

Why it forms

Most fistulas begin as an anal abscess — an infection in one of the small glands around the anus. When the abscess drains, a tract can be left behind that doesn't heal. Some fistulas are linked to conditions such as Crohn's disease.

Symptoms

Common symptoms include recurrent abscesses, persistent discharge of pus or blood near the anus, irritation of the surrounding skin, and sometimes pain or a visible opening.

How it's diagnosed

Examination, sometimes under anaesthetic, and imaging (such as MRI) help map the tract before treatment, because the relationship to the sphincter muscle determines the safest approach.

Surgical options

The aim is to heal the fistula while protecting continence. Options depend on the tract:

• Fistulotomy — laying the tract open, suitable for simpler, low fistulas.
• Seton — a thread placed to allow drainage and gradual healing.
• Sphincter-preserving techniques for more complex fistulas.

The takeaway

Fistulas rarely heal on their own and can recur, so specialist assessment and a tailored surgical plan matter.

This article provides general information and is not a substitute for individual medical advice. Please consult a qualified clinician about your own circumstances.