Dr. Solon Gonçalves Souza Menezes
Professor of Surgery — FAMED UFU · Robotic Surgery Certification (Intuitive / Albert Einstein Hospital) · Practices at Hospital UMC and Hospital Mater Dei Santa Genoveva, Uberlândia, Brazil · +55 (34) 99341-0915
An anal (or perianal) fistula is an abnormal tunnel connecting the inside of the anal canal to the skin around the anus. It almost always begins with an abscess: one of the small glands of the anal canal becomes infected, the pus finds its way to the skin and, after draining, the tract remains — through it, discharge, blood or pus come out intermittently, with pain and skin irritation. The Parks classification describes the fistula by the relationship of the tract to the sphincter muscles: intersphincteric (the most common and most superficial), transsphincteric (crosses the external sphincter), suprasphincteric and extrasphincteric. The more muscle the tract involves, the more “complex” the fistula is and the more the treatment needs to spare the sphincter to avoid incontinence.
A fistula does not heal on its own or with ointments or home remedies — treatment is surgical, and the ASCRS 2022 guideline organizes the options. For a simple fistula, with a normal sphincter, fistulotomy (laying open the tract) is the treatment of choice, with a strong recommendation: it has the highest healing rates and, in this group, minimal risk to continence. For complex fistulas, where laying open the tract would cut too much muscle, the sphincter-sparing techniques come in: ligation of the tract in the intersphincteric space (LIFT, strong recommendation for transsphincteric fistulas), the endorectal advancement flap (strong recommendation) and, as a frequent preliminary step, the seton — a thread that keeps the tract drained for weeks or months, controlling the infection before definitive treatment. Plugs and fibrin glue are considered of little efficacy.
Laser closure of the fistula tract is the most recent minimally invasive option: a laser fiber travels along the tunnel from the inside out and the energy destroys the lining and seals the tract, without cutting the sphincter. Dr. Solon Gonçalves offers the technique for complex fistulas, and its strong point is precisely the preservation of the muscle: in the meta-analyses, new incontinence after the laser is below 1%, and in the 2025 network meta-analysis no laser-treated patient had worsening of continence, versus 1.5% after LIFT and 7.3% after the flap. Its weak point is healing: cure in a single session is around 57% to 67% in the meta-analyses (ranging from 22% to 82% across series), recurrence is about 18%, and the only randomized trial against LIFT, in high fistulas, found similar and high failure in both arms (54% and 50%). The American guideline grades the laser 2C: reasonable short-term healing, long-term results unknown.
In practice, this means the laser is an honest option for those with a complex fistula who want, above all, to protect continence — accepting that the procedure may need to be repeated (laser retreatment cures about half of the failures) or that another technique may be needed. For a simple fistula, fistulotomy remains better, and the consensus of the laser experts themselves acknowledges this. Dr. Solon practices at Hospital UMC and Hospital Mater Dei Santa Genoveva in Uberlândia, Brazil, and defines the technique based on the proctological examination and, in complex fistulas, on pelvic magnetic resonance imaging, which maps the tract.
Book a consultationThe right technique for each type of fistula.
The choice follows the ASCRS 2022 guideline and depends on the type of fistula, the amount of sphincter involved, previous operations and the presence of Crohn's disease, which changes the approach. Pelvic magnetic resonance imaging is the reference examination for mapping complex and recurrent fistulas.
Simple fistula
Fistulotomy: the tract is laid open and heals from the inside out, with the highest healing rates and minimal risk of incontinence when the sphincter is normal. Strong recommendation (1B). This is not the laser's setting — it heals fewer fistulas in this group.
Transsphincteric fistula
LIFT (ligation of the tract in the intersphincteric space), advancement flap or laser closure, generally after a period with a seton. Published failure rates: LIFT 28.6%, flap 25.9%, laser 43.9% in the network meta-analysis — with worsening of continence in 1.5%, 7.3% and 0%, respectively.
Supra- and extrasphincteric fistulas
The most complex: staged treatment, with a seton and sphincter-sparing techniques; laser cure in these types is lower (36% to 42% in the pooled data).
Abscess and acute phase
The abscess is drained first; the fistula is treated later, once the tract has matured. In Crohn's disease, control of the inflammation with the gastroenterologist comes before any definitive treatment.
Healing and risk to the sphincter, technique by technique.
The numbers below come from the ASCRS 2022 guideline, the laser meta-analyses and the network meta-analysis that compared the four sphincter-sparing techniques (49 studies, 3,520 patients). Almost all the evidence on the laser is observational; the two randomized trials published up to 2026 are cited.
| Technique | Indication | Published healing / failure | Worsening of continence | Grade in ASCRS 2022 |
|---|---|---|---|---|
| Fistulotomy | Simple fistula, normal sphincter | The highest healing rates | Minimal when well indicated | 1B (strong) |
| Seton | Preliminary drainage; complex fistulas | Controls infection; does not cure on its own | Low (loose seton) | 2C for cutting seton |
| LIFT | Transsphincteric | Failure 28.6% (network meta-analysis) | 1.5% | 1B (strong) |
| Advancement flap | Complex, high transsphincteric | Failure 25.9% | 7.3% | 1B (strong) |
| Laser closure of the tract | Complex fistulas, when sparing the sphincter is the priority | Primary healing 57% to 67% in meta-analyses; failure 43.9% in the network meta-analysis; recurrence ~18%; retreatment cures ~half of failures | 0% to 1% | 2C (weak, low evidence) |
| Plug and fibrin glue | — | Of little efficacy | Low | 1B against routine use |
On a phone, drag the table sideways to see all the columns.
What to expect before and after surgery.
Preoperative preparation
The proctological examination identifies the openings and the tract; in complex or recurrent fistulas, or when Crohn's disease is suspected, pelvic magnetic resonance imaging is requested and, when necessary, colonoscopy. Assessment of baseline continence guides the technique. In cases with active infection, a seton is placed first — for the laser, the expert consensus recommends keeping the seton for at least two months before the procedure, which increases the chance of cure (70% versus 52% in the largest published series). Blood tests, an anesthetic assessment, fasting and simple bowel cleansing complete the preparation.
Recovery and postoperative care
The procedures are performed as day surgery or with one night in hospital, under spinal or general anesthesia. After the laser, pain is usually mild and the return to activities fast (about 5 to 10 days in the trials); after fistulotomy, the open wound heals from the inside out over 4 to 8 weeks, with dressings and sitz baths. Discharge from the external opening in the first weeks is expected with all techniques. Follow-up extends over months, because recurrence can appear late — in the series of 175 laser-treated patients, recurrence occurred at a median of 18 months.
Recurrence and incontinence: the two risks that guide the choice.
Every technique for anal fistula trades cure for risk to the sphincter, in different proportions. The numbers come from the sources cited in the references.
- Failure or recurrence — the central risk of sphincter-sparing techniques: 25.9% (flap), 28.6% (LIFT) and 43.9% (laser) in the network meta-analysis; after the laser, recurrence of about 18% and reoperation in about 36% of patients in the meta-analysis of 24 studies. Fistulotomy in a simple fistula has the lowest recurrence.
- Incontinence — the central risk of fistulotomy in fistulas that involve a lot of muscle, which is why it is reserved for simple ones; after the flap, worsening of continence in 7.3%; after LIFT, 1.5%; after the laser, 0% to 1% (mild leakage of gas or mucus).
- Postoperative abscess or infection — about 6.5% after the laser in the 2025 meta-analysis; possible with all techniques.
- Bleeding and pain — generally mild; minor complications after the laser in about 4% to 10%.
- Crohn's disease — raises the failure rate of all techniques and requires joint treatment with the gastroenterologist.
- General risks — anesthesia, transient urinary retention and infection, with low frequency.
Common questions about this procedure.
Can an anal fistula be cured? Can it close on its own?+
It can be cured, but the treatment is surgical: a fistula does not close on its own or with ointments or home remedies, because the tract is lined by tissue that prevents healing. Fistulotomy cures the vast majority of simple fistulas; in complex ones, sphincter-sparing techniques cure between 56% and 75% of cases in one session, and many failures are resolved with a second procedure.
Is a perianal fistula serious?+
It does not usually threaten life, but it is very troublesome, can cause recurrent abscesses and, without treatment, the tract can branch and become more complex. In rare cases of very old, neglected fistulas there is a risk of malignant transformation. That is why it should be treated.
Fistulotomy or laser: which is better?+
It depends on the fistula. In a simple fistula, with a normal sphincter, fistulotomy is better: it cures more and, in this group, barely affects continence — the guideline recommends it with a strong grade, and even the consensus of the laser experts acknowledges that the laser should not be the first option in these cases. In a complex fistula, where laying open the tract would cut too much muscle, the laser is an option that protects the sphincter (new incontinence below 1%), with cure around 57% to 67% in one session and the possibility of repetition.
What is the cure rate of laser fistula treatment?+
In the meta-analyses, primary healing is between 57% and 67%, with recurrence of about 18%; across individual series, it ranges from 22% to 82%, depending on the type of fistula, prior use of a seton and the experience of the service. In transsphincteric fistulas, cure is higher than in supra- and extrasphincteric ones (36% to 42%). Repeating the laser cures about half of the failures, raising the final success rate to around 70% to 74% in the largest series.
Can the fistula come back after surgery?+
It can, with any technique, and often late: in the largest laser series, recurrence occurred at a median of 18 months. Recurrence is lowest after fistulotomy of a simple fistula and higher after sphincter-sparing techniques — 26% to 44% failure in the network meta-analysis. That is why follow-up extends over months.
What is a seton?+
It is a thread (of silicone or another material) passed through the fistula tract and left in place for weeks or months. It keeps the tract drained, prevents new abscesses and matures the fistula for definitive treatment — for the laser, keeping the seton for at least two months beforehand increases the chance of cure. A loose seton does not cut the muscle; a cutting seton, which slowly divides the sphincter, is reserved for selected cases.
Does fistula surgery cause incontinence?+
It is the risk that defines the choice of technique. Fistulotomy is safe when the fistula is simple and the sphincter is normal; in fistulas involving a lot of muscle, it is avoided. Among the sphincter-sparing techniques, worsening of continence was 7.3% after the flap, 1.5% after LIFT and 0% after the laser in the network meta-analysis — generally mild leakage of gas or mucus.
How long is the recovery and the sick leave?+
After the laser and LIFT, return to activities takes around one to two weeks (5 to 10 days in the trials). After fistulotomy, the wound heals in 4 to 8 weeks, but work without effort is usually resumed in one to two weeks. Sick leave is defined case by case.
Can an anal fistula turn into cancer?+
Malignant transformation is rare and happens in very old, chronically inflamed fistulas. It is one more reason to treat the fistula and to investigate, with biopsy, tracts that change in appearance or do not heal as expected.
Do I need an MRI?+
For simple fistulas, the proctological examination is usually enough. For complex or recurrent fistulas, those with multiple openings or suspected Crohn's disease, pelvic magnetic resonance imaging maps the tract and its branches and is essential for planning surgery.
Do you operate through the SUS, the Brazilian public health system?+
I do operate through the SUS. I am a Professor of Surgery at the School of Medicine of the Federal University of Uberlândia and I operate on patients at the university hospital, HC-UFU. The route, however, does not go through my private practice: to be operated on through the SUS you must go to the health post or Basic Health Unit nearest your home, be assessed by a doctor and, if surgery is indicated, be placed in your municipality's regulation queue. The surgeon does not choose who gets operated on through the SUS — the queue is followed strictly, according to SUS rules.
Hospital facilities in Uberlândia, Brazil.
Hospital Mater Dei Santa Genoveva
Av. Vasconcelos Costa, 967 — Martins, Uberlândia-MG
Open in Google Maps →Content reviewed by Dr. Solon Gonçalves Souza Menezes — CRM-MG 79366, RQE 60355 (GI Surgery), RQE 44656 (General Surgery). Professor of Surgery at FAMED-UFU and Supervisor of the General Surgery Medical Residency Program at HC-UFU. ORCID. Last reviewed: October/2026.
- Gaertner WB, Burgess PL, Davids JS, et al. The American Society of Colon and Rectal Surgeons Clinical Practice Guidelines for the Management of Anorectal Abscess, Fistula-in-Ano, and Rectovaginal Fistula. Dis Colon Rectum. 2022;65(8):964-985. doi:10.1097/DCR.0000000000002473
- Fuschillo G, Pata F, D'Ambrosio M, et al. Failure rates and complications of four sphincter-sparing techniques for the treatment of fistula-in-ano: a systematic review and network meta-analysis. Tech Coloproctol. 2025;29(1):116. doi:10.1007/s10151-025-03152-0
- Elfeki H, Shalaby M, Emile SH, et al. A systematic review and meta-analysis of the safety and efficacy of fistula laser closure. Tech Coloproctol. 2020;24(4):265-274. doi:10.1007/s10151-020-02165-1
- Frountzas M, Stergios K, Nikolaou C, et al. Could FiLaC™ be effective in the treatment of anal fistulas? A systematic review of observational studies and proportional meta-analysis. Colorectal Dis. 2020;22(12):1874-1884. doi:10.1111/codi.15148
- Duda JR, de Oliveira LGAM, Ferreira LF, et al. Effectiveness of Laser-Based Fistula Therapies with and without Adjunctive Measures in Anal Fistulas Management: A Systematic Review and Single-Arm Meta-Analysis. Int J Colorectal Dis. 2025;40(1):196. doi:10.1007/s00384-025-04995-7
- Low JQL, Rajandram R, Aziz MRA, Roslani AC. Postoperative pain following laser fistula closure versus ligation of the intersphincteric fistula tract: a prospective double-blinded randomized controlled trial. World J Surg. 2024;48(8):1990-1999. doi:10.1002/wjs.12242
- Patel KR, Jauhari RK, Shukla P. A Randomized Controlled Trial Comparing Laser Versus Open Surgical Approaches in the Management of Fistula-in-Ano at a Tertiary Care Center. Cureus. 2025;17(8):e90471. doi:10.7759/cureus.90471
- Giamundo P, De Angelis M. Treatment of anal fistula with FiLaC: results of a 10-year experience with 175 patients. Tech Coloproctol. 2021;25(8):941-948. doi:10.1007/s10151-021-02461-4
- Wilhelm A, Fiebig A, Krawczak M. Five years of experience with the FiLaC™ laser for fistula-in-ano management: long-term follow-up from a single institution. Tech Coloproctol. 2017;21(4):269-276. doi:10.1007/s10151-017-1599-7
- Ambe PC, Martin-Martin GP, Alam AA, et al. Laser fistula treatment: beyond the controversial aspects: best clinical practice recommendations from an international group of surgeons with extensive experience in the procedure — the FiLaC recommendations. Tech Coloproctol. 2025;29(1):131. doi:10.1007/s10151-025-03164-w