Anal fistula surgery

What is anal fistula surgery?

An anal fistula (fistula-in-ano) is a small tunnel that runs from the inside of the back passage to the skin near the anus. Most form after an anal abscess (a collection of pus) has drained, leaving a tract behind that keeps getting infected or leaking. Surgery aims to clear the infection and close the tunnel so it stops discharging.

The tricky part is that fistulas often run through or close to the ring of muscle (the anal sphincter) that keeps you continent. The surgeon has to balance getting rid of the fistula against protecting that muscle. The right operation depends on how the tunnel runs in relation to the muscle, which is why an examination — and sometimes an MRI or examination under anaesthetic — comes first.

No single operation suits every fistula. Simple, low fistulas can often be laid open in one go. More complex ones may need a thread (seton) left in place for weeks or months, or a muscle-sparing technique, and sometimes more than one procedure. Surgery treats the fistula — it does not treat any underlying cause, such as Crohn's disease, which needs its own care.

Types & techniques

There isn't one single operation. The right approach depends on you — which is something to discuss with your surgeon.

Laying open versus muscle-sparing surgery

There is a genuine trade-off between clearing the fistula and protecting continence. Your surgeon should explain which way the balance falls for your particular fistula.

Preparing for your surgery

• See a colorectal surgeon who examines the area; an MRI scan or an examination under anaesthetic is often used to map how the tunnel runs before deciding on the operation.
• Ask the surgeon which technique they plan to use and what it means for your bowel control.
• Mention any bowel condition, especially Crohn's disease or ulcerative colitis, as this changes the approach.
• Tell the team about all medicines, including blood thinners, and about diabetes or anything affecting healing.
• Stop smoking if you can, as it slows wound healing.
• Arrange a lift home and time off; you may not be able to drive straight after a general anaesthetic.
• Plan for daily bathing or showering and for managing dressings at home.

What happens

Most fistula operations are done under general anaesthetic as a day case. The surgeon first examines the back passage to confirm how the tunnel runs, sometimes passing a fine probe along it.

What happens next depends on the type of fistula. A simple one may be laid open (fistulotomy). A more complex one may have a soft thread (seton) passed through it and left in place, or be treated with a muscle-sparing technique such as LIFT or a flap. The wound is usually left open to heal naturally rather than stitched closed, so it can drain.

You wake up in recovery and, once comfortable and able to pass urine, most people go home the same day. You will be told how to look after the area and when you will be seen again.

Is this operation right for me?

A good consultation should explore whether it's the right choice for you now — including reasons to wait or consider something else.

Before you decide

Use this as a shared-decision checklist. The aim is not just “can this be done?”, but whether it is right for you, now, with the risks and alternatives clearly understood.

Anaesthetic choices

The safest option depends on the operation, your health, the facility and your surgeon/anaesthetist. Ask what is planned and why.

The risk that matters most is to continence — control of wind and stool — because the fistula runs near the muscle that provides it. Operations that divide muscle (fistulotomy) carry more of this risk than muscle-sparing techniques, but muscle-sparing techniques are less likely to cure the fistula first time. Ask your surgeon specifically how their proposed operation affects your bowel control and what the chance of cure is.

Published figures to discuss

Outcomes vary a lot with the type and complexity of the fistula, how much muscle is involved, the technique used, and whether there is an underlying condition such as Crohn's disease. Studies define 'cure' and measure incontinence differently, so figures should be treated with caution. The central, well-recognised trade-off is between clearing the fistula and protecting bowel control.

These are literature figures, not a personalised prediction. Your own risks and likely benefits depend on your circumstances, your health, and how your care is carried out and followed up.

Recovery — what to expect, and when

Most people go home the same day and are back to light activity within a few days, but the wound itself is usually left open and can take weeks to several months to heal fully, especially for larger or deeper fistulas.

• Soreness and discomfort, often worse for the first few bowel movements
• Ongoing discharge, oozing or spotting of blood from an open wound
• A wound that takes longer to heal than you might expect
• Itching as the area heals

Aftercare

• Bathe or gently shower the area daily, and after opening your bowels, to keep it clean; avoid perfumed soaps until healed.
• Take painkillers as advised, including before opening your bowels if that is painful.
• Keep stools soft with fluids, fibre and laxatives if recommended, to make bowel movements easier.
• Change dressings as shown, and 'digitate' the wound only if your surgeon has told you to.
• Avoid heavy lifting and strenuous exercise in the first week or two.
• Keep follow-up appointments so healing can be checked and any further treatment planned.
• Know who to contact if you have heavy bleeding, fever or worsening pain.

• Painkillers at home and a plan to take them before bowel movements
• Soft-stool plan (fluids, fibre, laxatives if advised)
• Dressings and a way to bathe or shower the area
• Loose, comfortable clothing
• Time off work arranged
• Lift home after a general anaesthetic
• Clinic or out-of-hours number saved

Scars and how they heal

Because the wound is often left open to heal from the inside, there is usually no neat stitch line. As it heals it leaves a small scar near the anus. Muscle-sparing operations and flaps may leave a small wound or scar inside or just outside the back passage.

⚠ Get urgent help if…

• Heavy or persistent bleeding that does not settle
• Fever, chills or feeling generally unwell (possible infection)
• Increasing pain, redness, swelling or new discharge of pus
• Being unable to pass urine
• A new lump, swelling or worsening discharge after initial healing
• New or worsening difficulty controlling wind or stool

Who to contact: your surgeon or clinic first (keep their number to hand). For urgent advice when you can't reach them, call NHS 111. In an emergency, call 999.

General guidance — it doesn't replace the specific advice your surgeon gives you.

Results & realistic expectations

A good result means the fistula heals and stops discharging, while keeping reasonable bowel control. For simple fistulas treated by fistulotomy this is often achieved in one operation. For complex fistulas the picture is less predictable: a staged approach is common, healing takes longer, and the fistula can come back.

No operation can guarantee both a complete cure and perfect continence. Surgery also does not treat any underlying cause, such as Crohn's disease, so symptoms can return if that is not managed.

Many fistulas, once healed, stay healed. However, fistulas can recur — sometimes months or years later — particularly complex ones, those that involved a lot of muscle, or those linked to Crohn's disease. Muscle-sparing techniques tend to have higher recurrence than laying open. If symptoms return, you should be reassessed rather than assume it is the same problem.

Combining with other procedures

Fistula surgery is sometimes combined with, or follows, drainage of a perianal abscess. If a fistula is found at the time an abscess is drained, the surgeon may place a draining seton then, and plan definitive surgery later once infection has settled.

Follow-up & long-term care

Follow-up depends on the operation. After a simple fistulotomy you may not need a routine appointment unless there are problems, but you should be able to contact the team if healing is slow or symptoms persist. After a seton or complex repair, you will usually be reviewed to plan the next step.

• Keep stools soft and avoid straining to reduce the chance of recurrence.
• Maintain good hygiene of the area as it heals.
• If you have Crohn's disease, keep this well controlled with your specialist.
• Report any recurrence of discharge, pain or swelling promptly.

Revision and secondary surgery reality

• Complex fistulas frequently need staged surgery — a seton first, then a definitive procedure.
• Muscle-sparing techniques may need to be repeated or converted to another technique if they do not work first time.
• A recurrent fistula should be re-mapped (often with MRI) rather than simply re-operated on blindly.
• Fistulas linked to Crohn's disease may need long-term management rather than a single curative operation.

Ask your surgeon for their own revision rate, what counts as a revision, and what is included in the written aftercare policy.

What good aftercare looks like

• Clear written instructions on bathing, dressings and pain relief, including before bowel movements.
• A named contact route for bleeding, infection or slow healing.
• A plan for follow-up and for any staged or further surgery.
• Advice to keep stools soft and avoid straining.
• Joined-up care with a gastroenterologist if Crohn's disease is involved.

What affects the cost

Costs vary a great deal between people and providers, and we don't publish prices. What matters is understanding what drives the cost and making sure your quote is complete. The main things that affect it:

• The surgeon's fee and the type of operation (fistulotomy, seton, LIFT, flap or newer techniques).
• Anaesthetic fee (general or spinal) and theatre or facility charges.
• Whether imaging such as an MRI or an examination under anaesthetic is needed first.
• Whether the fistula is simple or complex, and whether staged surgery is likely.
• Length of stay if an overnight admission is needed.
• Follow-up appointments, dressings and aftercare.
• What is included if the fistula recurs or further surgery is needed.

• The surgeon's fee and which operation is planned
• Anaesthetic and theatre or facility fees
• Any imaging (MRI) or examination under anaesthetic
• Follow-up appointments and dressings
• Whether more than one procedure may be needed and how that is charged
• Cancellation policy
• What happens, and what it costs, if the fistula recurs or a complication occurs

On the NHS? Anal fistula surgery is commonly provided on the NHS when there are symptoms; some people use private care for speed of access or to choose their surgeon.

You're entitled to your total cost in writing — including aftercare and any revision — before you decide.

Consent traps and marketing red flags

These are not small details. They are often where patients lose choice, time to reflect, or realistic expectations.

Choosing a surgeon safely

• Check your surgeon is on the GMC Specialist Register for this area.
• Make sure they practise at a CQC-registered location, and look for membership of bodies like BAAPS or BAPRAS.
• You're entitled to a two-stage consent process with time to reflect (a cooling-off period). The surgeon who will operate must consent you — not a salesperson.
• Be wary of pressure: time-limited offers, discounts or deposits taken before you've had time to think are red flags, not bargains.
• You're entitled to your total cost in writing — including aftercare and any revision — before you decide.

How Vuemedics verifies every consultant →

Take this to your consultation. A good surgeon will welcome every one of these.

• How does my fistula run in relation to the muscle, and have you mapped it (for example with an MRI)?
• Which operation do you propose, and what does it mean for my bowel control?
• What is the realistic chance this clears the fistula, and might I need more than one operation?
• Will the wound be left open, and how long is it likely to take to heal?
• Could there be an underlying cause such as Crohn's disease, and how would that change things?
• What should I watch for, and who do I contact if healing is slow or symptoms return?
• Are you on the GMC Specialist Register for this area, and which Royal College or professional body are you a member of?
• Will you be the surgeon who carries out my operation, and who looks after me afterwards?
• What are the risks for someone like me, and how often do your own patients have a problem or need it repeated or redone?
• What does a realistic result look like — and what can this operation not achieve?
• What are my options, including waiting, doing nothing for now, or choosing a different approach?
• Can I have written information, results and aftercare instructions in a format I can use, including any accessibility or communication support I need?
• What is the total cost in writing, including any follow-ups, and how much time do I have to decide?

Find a verified surgeon for anal fistula surgery

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How we made this page

Medically reviewed by a GMC-registered consultant. Written in plain English, checked against NHS, NICE, GMC and relevant Royal College / specialist-society guidance, and kept under review. No clinic paid to appear on this page, and we publish no pricing. This is general information to help you prepare — it is not a substitute for advice from your own clinician. How we review our guides →

Source hierarchy: UK regulator and NHS/NICE guidance first, then relevant Royal College or specialist-society guidance, then peer-reviewed evidence for procedure-specific figures where available.

Sources & standards: NHS — Anal fistula Guy's and St Thomas' NHS — Anal fistula treatment and recovery Royal College of Surgeons of England — The Annals (RCS publishing) Surgical treatments for anal fistula: network meta-analysis — PMC Long-term outcome of anal fistula (retrospective study) — Scientific Reports

Reviews reflect patients' experience of care, not clinical outcomes. For procedure volumes and outcome data see PHIN.

Last medically reviewed 2026-09-21. Spotted something wrong or out of date? Report an error in this guide.