At a glance
Incontinence risk is the most significant concern for people facing fistula surgery. It is a legitimate concern that deserves honest, clear information. This guide covers what the risk actually involves, how it varies by procedure type, and how to have a productive conversation with your surgeon about it.
Understanding the risk
Why the risk exists
The anal sphincter muscles control continence. Fistula surgery sometimes involves operating on or near these muscles. When sphincter muscle is divided — as in a fistulotomy — there is a risk that continence may be affected.
The risk depends on:
- How much sphincter is involved — a superficial fistula involving minimal sphincter carries low risk; a complex fistula involving significant sphincter carries higher risk
- The surgical technique — fistulotomy (laying open) divides muscle; sphincter-preserving techniques (advancement flap, LIFT) do not
- Previous surgery — the cumulative effect of multiple operations on the sphincter increases risk
- Baseline sphincter function — people with pre-existing weak sphincters (from childbirth, age, or other factors) may be at higher risk
What incontinence looks like in practice
When continence changes occur after fistula surgery, they most commonly present as:
- Difficulty controlling gas — the most common and mildest form. This means gas passes unexpectedly rather than being held until an appropriate moment.
- Minor soiling — small amounts of mucus or stool on underwear. Often manageable with pads and does not significantly affect daily life.
- Urgency — less time between feeling the need to go and needing to reach a toilet. This is less common.
- Significant faecal incontinence — inability to control bowel movements. This is uncommon with modern surgical techniques and experienced surgeons.
The numbers in context
Reported incontinence rates vary widely in medical literature depending on how incontinence is defined and measured:
- Simple fistulotomy for superficial fistulas: low risk — most studies report rates in single digits
- Complex fistula surgery: higher risk, which is why sphincter-preserving techniques are used
- Sphincter-preserving techniques: designed specifically to minimise this risk
Your surgeon can provide specific data relevant to your fistula type and the planned procedure.
Surgical techniques and how they relate to risk
Fistulotomy
The fistula tract is laid open. Effective but involves dividing sphincter muscle. Generally reserved for simple, superficial fistulas where minimal muscle is involved.
Seton placement
A thread placed through the fistula tract. Does not divide the sphincter in one step. May be used as a staged approach before definitive repair.
Advancement flap
Healthy tissue is moved to cover the internal opening of the fistula. Does not divide the sphincter. Used for complex fistulas where sphincter preservation is a priority.
LIFT procedure
The fistula tract is tied off between the sphincter muscles. Preserves the sphincter. Increasingly used for appropriate fistula types.
Having the conversation with your surgeon
Questions to ask
- What type of fistula do I have, and how much sphincter is involved?
- What surgical technique do you recommend, and why?
- What is the specific incontinence risk for this procedure?
- What sphincter-preserving options are available?
- What is your personal experience and success rate with this procedure?
- What continence changes should I watch for and report after surgery?
- What options exist if incontinence does occur?
What to listen for
A good surgeon will:
- Discuss the risk honestly without minimising or catastrophising
- Explain their technique choice and the rationale behind it
- Have experience with the procedure they are recommending
- Describe what they would do differently if the first approach does not work
- Welcome your questions and take them seriously
If changes occur after surgery
If you notice any changes in gas control, soiling, or urgency after fistula surgery:
- Report it to your surgical team — they need to know
- Keep a log — when it happens, how often, what triggers it
- Understand that some changes are temporary — mild gas control issues in the early weeks may resolve as healing completes
- If changes persist — pelvic floor exercises, biofeedback therapy, and other interventions can help
- Do not suffer in silence — this is a known risk, and there are management options