In short
An anal fistula is an abnormal tunnel running from inside the anal canal to the skin outside. It usually starts as an abscess: the infection drains, but the tunnel it made stays open. That is why a fistula discharges, settles, and flares again rather than simply healing.
Why fistulas need a specialist
A fistula is not difficult to open up. It is difficult to open up without cutting through the muscle you rely on for control, because the tract usually runs through some part of the sphincter complex.
How much muscle is involved, and where, is the entire problem. Get that assessment wrong and you either leave disease behind — so it recurs — or you take too much muscle and cause incontinence. Neither is acceptable.
Mapping comes before operating
The tract is traced by careful examination under anaesthetic and, for anything not clearly simple, by MRI. What is being established is the internal opening, the course of the tract, how much sphincter it crosses, and whether there are secondary branches that a single procedure would miss.
Recurrence after fistula surgery is most often a missed branch or a missed internal opening — not bad luck.
Simple and complex
A low fistula crossing little or no muscle can often be laid open in one procedure, with a high success rate and minimal risk to continence.
A high or trans-sphincteric fistula, a recurrent one, or one with branches is complex, and laying it open is not an option. These need a sphincter-preserving strategy, sometimes staged.
Sphincter-preserving options
Several approaches treat the tract without dividing the muscle: a seton to let infection settle first, LIFT, an advancement flap, or laser closure of the tract. Which one fits depends on the anatomy, whether infection is still active, and whether there has been previous surgery.
Complex fistulas sometimes take more than one operation to resolve. That is not a failure — it is how you keep continence intact while clearing the disease.
What recovery looks like
Fistula wounds heal from the inside out and are kept deliberately open so they do not close over infection. That means several weeks of dressings and reviews rather than a single post-op visit. Knowing this in advance makes the recovery much easier to tolerate.
Seek care promptly if
- There is increasing pain, swelling or fever — infection may be building again
- The discharge becomes heavier or foul-smelling
- You notice any change in control of wind or stool
- You have diarrhoea, weight loss or mouth ulcers alongside it — Crohn's disease can present as a fistula
- A previously treated fistula has come back
These are the symptoms that should not wait.
Common questions
- Can a fistula heal on its own?
- Very rarely. The tunnel is lined and stays open, which is why it discharges, appears to settle, then flares again. Definitive treatment is surgical.
- Will I lose control after fistula surgery?
- Protecting continence is the priority that shapes the whole plan. For low, simple fistulas the risk is very small. For high or complex ones, sphincter-preserving techniques are used specifically so the muscle is not divided — which is also why those cases sometimes need staging.
- Why might it come back?
- Almost always because a secondary branch or the true internal opening was missed. That is why mapping before surgery matters more than the choice of technique.
General information only. Anorectal symptoms overlap and only an examination can tell them apart — please do not use this page to diagnose yourself.