Fistula-in-Ano Surgery: Understanding the Different Surgical Options, Anatomy, Techniques and Outcomes

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7. How Successful is LIFT?

Published results vary substantially.

An earlier systematic review found a pooled healing rate of approximately 71%, although individual studies ranged widely. (PubMed)

More recent evidence continues to show variability.

A 2025 systematic review and network meta-analysis of sphincter-sparing procedures reported failure rates of approximately:

• LIFT: 28.6%
• VAAFT: 22.3%
• FiLaC: 43.9%
• Endoanal advancement flap: 25.9%

These figures should not be interpreted as direct head-to-head success rates because the studies differed in patient selection, fistula complexity and follow-up. (PubMed)

The major advantage of LIFT is not necessarily that it always has the highest healing rate.

Its major advantage is:

It can treat a transsphincteric fistula without deliberately dividing the external sphincter.

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8. Advancement Flap

An endorectal or endoanal advancement flap is another sphincter-preserving procedure.

Instead of opening the entire fistula tract, the surgeon attempts to close the internal opening.

How is it performed?

Broadly:

1. Identify the internal opening.
2. Prepare the surrounding tissue.
3. Raise a healthy mucosal/submucosal flap.
4. Excise or curette the internal fistula opening.
5. Close the internal opening.
6. Advance the flap over the defect.
7. Secure the flap without excessive tension.

The external opening may be opened or drained depending on the anatomy.

The concept is:

Remove the internal source of contamination and cover it with healthy vascularized tissue.

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9. When is Advancement Flap Useful?

It may be considered for:

• High transsphincteric fistula
• Complex fistula
• Recurrent fistula
• Fistula unsuitable for fistulotomy
• Fistula where LIFT is technically unsuitable or has failed
• Selected cases with difficult internal openings

It is particularly useful when the surgeon wants to preserve the sphincter but cannot safely perform a fistulotomy.

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Limitations of Advancement Flap

Failure may occur because of:

• Poor blood supply
• Excessive tension
• Infection
• Persistent internal opening
• Crohn’s disease
• Previous surgery and scarring
• Radiation
• Smoking
• Persistent distal tract or abscess

The ASCRS notes that recurrence after advancement flap can be substantial and that factors such as Crohn’s disease, radiation, previous repair and smoking can adversely affect healing. (FASCRS)

A 2024 meta-analysis also confirms that advancement flap is an effective sphincter-preserving option, but outcomes vary according to patient and fistula characteristics. (PubMed)

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10. Seton — Usually a Staged Strategy Rather Than a Final Cure

A seton is a loop of suture or soft material passed through the fistula tract.

There are two fundamentally different concepts:

Loose/draining seton

Its purpose is to:

• Maintain drainage
• Prevent premature closure of the external opening
• Control sepsis
• Allow inflammation to settle
• Allow the tract to mature

A loose seton is particularly useful when there is:

• Active infection
• Abscess
• Complex fistula
• Crohn’s disease
• High transsphincteric fistula
• Need for staged surgery

The ASCRS patient guidance describes draining setons as a method of maintaining controlled drainage and allowing inflammation to settle before definitive treatment. (FASCRS)

Cutting seton

A cutting seton gradually cuts through the sphincter while fibrosis develops behind it.

Although historically used, it carries a greater concern for continence disturbance.

For this reason, a cutting seton should not be considered equivalent to a modern sphincter-preserving loose seton strategy.

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11. Staged Surgery

Complex fistulas often benefit from a staged approach.

Stage 1

Drain infection and control sepsis

Possible procedures include:

• Abscess drainage
• Debridement where appropriate
• Loose seton placement
• Drainage of secondary cavities

Stage 2

After inflammation and infection have settled:

• LIFT
• Advancement flap
• Selected minimally invasive procedure
• Fistulotomy if the residual tract has become suitable
• Other individualized sphincter-preserving procedure

This approach is particularly useful when immediate definitive surgery would be performed in an inflamed or poorly defined field.

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12. VAAFT — Video-Assisted Anal Fistula Treatment

VAAFT uses a small fistuloscope introduced through the external opening.

The surgeon can:

1. Identify the fistula tract under direct vision.
2. Locate the internal opening.
3. Clean/debride the tract.
4. Treat the tract.
5. Close the internal opening.

The attraction of VAAFT is that it is minimally invasive and sphincter-preserving.

It can be particularly attractive in selected complex fistulas where preservation of the sphincter is important.

However, long-term comparative evidence remains less mature than for traditional fistulotomy.

The recent meta-analysis reported a failure rate of approximately 22.3%, but also emphasized that the available studies are heterogeneous and that VAAFT did not demonstrate a statistically significant superiority over LIFT in network comparison. (PubMed)

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13. FiLaC — Fistula Laser Closure

FiLaC uses a radial laser fiber placed inside the fistula tract.

The laser energy is delivered along the tract to collapse and seal it while attempting to preserve the sphincter.

Its theoretical advantages include:

• Minimal tissue disruption
• No deliberate sphincter division
• Small external wound
• Potentially less postoperative pain
• Sphincter preservation

However, published outcomes are variable.

The 2025 systematic review reported a failure rate of approximately 43.9% in the included studies, although the wide range between studies highlights the uncertainty around the true long-term effectiveness. (PubMed)

Therefore, FiLaC should be viewed as a selected sphincter-preserving option rather than automatically the best procedure for every fistula.

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14. Fibrin Glue and Fistula Plug

Other sphincter-preserving approaches include:

Fibrin glue

The fistula tract is cleaned and filled with fibrin sealant.

Advantages:

• No sphincter division
• Relatively simple

Limitations:

• Variable healing
• Recurrence can be significant
• Less predictable in complex fistulas

Fistula plug

A biological or synthetic plug is placed into the fistula tract.

Again, the principal advantage is sphincter preservation, but healing rates are variable.

These techniques may be considered in selected situations but are generally less predictable than a well-selected definitive surgical procedure.

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15. What About Recurrence?

Recurrence is one of the most important outcomes when discussing fistula surgery.

But “recurrence rate” is difficult to compare directly between studies because:

• Definitions of healing differ
• Follow-up duration differs
• Simple and complex fistulas are mixed
• Some studies rely on clinical examination
• Others use MRI or endoanal ultrasound
• Patient populations differ

A large network meta-analysis of 52 randomized trials found no statistically significant difference in short- or long-term success between the various procedures studied, highlighting how strongly patient selection and fistula anatomy influence outcomes. (Springer)

Therefore, the best operation is not necessarily the procedure with the highest published success rate.

It is the procedure that is best matched to that patient’s anatomy.

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16. What About Fecal Incontinence?

This is arguably the most important consideration in fistula surgery.

Incontinence may involve:

• Flatus
• Liquid stool
• Stool staining
• Urgency
• Difficulty controlling stool

The risk increases when significant sphincter muscle is divided or damaged.

This is why the principle of modern fistula surgery is:

Do not sacrifice sphincter unnecessarily to obtain fistula healing.

A 2023 network meta-analysis of 52 randomized trials found LIFT ranked best for minimizing bowel incontinence among the procedures evaluated for both simple and complex fistulas. However, the authors also emphasized that there was insufficient evidence to declare one procedure universally superior for fistula healing. (Springer)

A newer 2025 review of sphincter-sparing procedures reported continence disturbance of approximately:

• LIFT: 1.5%
• Endoanal flap: 7.3%
• VAAFT: no worsening continence reported in the included studies
• FiLaC: no worsening continence reported in the included studies

Again, these figures should be interpreted cautiously because the underlying studies were heterogeneous. (PubMed)

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17. A Practical Comparison of Major Operations

Procedure	Best suited for	Sphincter division	Healing / recurrence	Continence risk
Fistulotomy	Simple, low fistula	Yes, limited	Generally highest healing in appropriately selected simple fistulas	Low when carefully selected; increases with sphincter division
Fistulectomy	Selected simple fistula	May involve sphincter	Good, but larger tissue disruption	Depends on sphincter involvement
LIFT	Transsphincteric fistula	No deliberate sphincter division	Variable; failure ~29% in recent pooled evidence	Very low in contemporary series
Advancement flap	Complex/high fistula	No deliberate division	Variable; failure ~26% in recent pooled evidence	Generally low, but not zero
Loose seton	Sepsis/complex fistula/staged treatment	No	Usually drainage/staging rather than definitive cure	Very low
Cutting seton	Selected complex fistula	Gradual division	Can be effective	Higher continence concern
VAAFT	Selected complex fistula	No	Failure ~22% in recent pooled evidence	Very low in reported studies
FiLaC	Selected sphincter-preserving cases	No	Failure ~44% in recent pooled evidence	Very low in reported studies
Fibrin glue/plug	Selected cases	No	Variable	Very low

The numerical estimates above come from heterogeneous studies and should not be interpreted as direct head-to-head probabilities for an individual patient. (PubMed)

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18. How Do We Choose the Operation?

A useful clinical decision-making framework is:

Step 1 — Is there an abscess or active sepsis?

YES

Control sepsis first.

Drain the abscess and, where appropriate, use a loose seton.

Definitive fistula surgery may be performed later once the anatomy is clearer and inflammation has settled.

NO

Proceed to anatomical assessment and definitive planning.

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Step 2 — How much external sphincter does the fistula involve?

Minimal sphincter involvement

Consider:

Fistulotomy

This may offer the highest probability of cure in an appropriately selected simple fistula.

Significant sphincter involvement

Avoid unnecessary sphincter division.

Consider:

LIFT / advancement flap / selected VAAFT / FiLaC / staged strategy

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Step 3 — Is the fistula complex?

Look for:

• Horseshoe extension
• Secondary tracts
• Large cavity
• Multiple external openings
• Recurrent disease
• Crohn’s disease
• Supralevator extension

If present, a simple fistulotomy is generally inappropriate.

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19. An Important Concept: “The Lowest-Risk Operation That Can Reliably Cure the Fistula”

There is no universally “best” fistula operation.

For example:

Low simple fistula

Fistulotomy may be preferable to an elaborate sphincter-preserving procedure.

Why?

Because there is little sphincter to sacrifice and fistulotomy can provide very high healing rates.

High transsphincteric fistula

LIFT may be preferable.

Why?

Because cutting the tract open could divide a substantial amount of external sphincter.

High/complex fistula with unsuitable intersphincteric anatomy

Advancement flap may be preferable.

Fistula with active abscess

Drainage ± loose seton → reassessment → definitive surgery

may be safer than attempting immediate definitive repair.

Recurrent fistula

The previous operative history becomes extremely important.

The surgeon should determine:

• What sphincter has already been divided?
• Where is the current internal opening?
• Is there an occult secondary tract?
• Is there an abscess?
• Is the current anatomy suitable for LIFT?
• Would an advancement flap be more appropriate?

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20. Can a Failed LIFT Still Be Useful?

Yes.

One interesting advantage of LIFT is that failure does not necessarily leave the patient with a worse sphincter situation.

The persistent tract may become an intersphincteric fistula.

That tract can sometimes subsequently be treated with a relatively straightforward fistulotomy.

Therefore, LIFT can sometimes be thought of as:

A sphincter-preserving attempt at definitive treatment that may also convert a difficult transsphincteric fistula into a simpler tract if it fails.

This is one reason LIFT remains an important operation in the surgical armamentarium. (PubMed Central (PMC))

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21. The Role of Patient Factors

The anatomy of the fistula is not the only consideration.

The surgeon should also consider:

• Baseline continence
• Age
• Previous anal surgery
• Previous fistulotomy
• Previous obstetric sphincter injury
• Gender and fistula location
• Crohn’s disease
• Smoking
• Immunosuppression
• Diabetes and wound healing
• Previous radiation
• Patient preference
• Ability to attend follow-up

A patient with pre-existing borderline continence may reasonably choose a sphincter-preserving procedure even when a limited fistulotomy could technically be performed.

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22. Fistula Surgery Is an Anatomy-Driven Decision

The most important lesson is that the MRI report should not simply say “fistula present.”

For surgical planning, the surgeon needs to know:

Where is the internal opening?

Where is the external opening?

What is the course of the tract?

How much external sphincter is involved?

Are there secondary branches?

Is there a horseshoe component?

Is there an abscess?

Is there supralevator extension?

Has the patient undergone previous fistula surgery?

Only after answering these questions should the definitive operation be selected.

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23. Final Take-Home Message

Anal fistula surgery is fundamentally a balance between two objectives:

1. Cure the fistula

and

2. Preserve continence.

Fistulotomy remains the benchmark for appropriately selected low/simple fistulas because it can provide very high healing rates.

LIFT is an important sphincter-preserving option for transsphincteric fistulas.

Advancement flap is another valuable sphincter-preserving procedure, particularly when LIFT is unsuitable or has failed.

Loose seton is primarily a drainage and staging tool rather than necessarily a definitive cure.

VAAFT and FiLaC offer minimally invasive, sphincter-preserving approaches for selected patients, but their long-term evidence is less mature and outcomes remain variable.

Staged surgery is often the most logical strategy when there is active sepsis, abscess, complex branching or uncertain anatomy.

The central principle is therefore:

The best fistula operation is not the operation with the most impressive success rate in a study. It is the operation that achieves the highest probability of healing while causing the least unnecessary damage to the patient’s sphincter.

For this reason, fistula surgery should be individualized according to MRI anatomy, sphincter involvement, internal opening, sepsis, previous surgery and baseline continence.

This article is intended for medical education and does not replace individualized examination, MRI interpretation and surgical decision-making by a colorectal/anal fistula specialist.