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Original Contributions: Anorectal

Long-term Outcomes of Laser Ablation of Fistula Tract for Fistula-in-Ano: A Considerable Option in Sphincter Preservation

Isik, Ozgen M.D.1; Gulcu, Baris M.D.2; Ozturk, Ersin M.D., Ph.D., E.B.S.Q-c.1–3

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Diseases of the Colon & Rectum: June 2020 - Volume 63 - Issue 6 - p 831-836
doi: 10.1097/DCR.0000000000001628
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Treatment of fistula-in-ano is still a challenging state because of the concern of fecal incontinence, particularly for high transsphincteric fistulas. In this manner, sphincter-preserving methods are preferred despite a high risk of persistence. Rapid development of health industry and technology provides new treatment options in this complex disease, and laser ablation of fistula tract (LAFT) is one of them.

There were 3 studies introducing the initial experiences regarding LAFT,1–3 and all presented that this method was safe and feasible with good likelihood of success. However, the data presenting the long-term outcomes of LAFT showed that it was not a miraculous option treating every single fistula.4–6

LAFT may be a considerable alternative in sphincter-preserving fistula-in-ano treatment for carefully selected patients. However, there are concerns regarding LAFT, such as its actual success rate, whether the healing is because of curettage or laser itself, or what type of fistulas are good candidates for LAFT. By being one of the earliest performers of this procedure, we improved our experience in both technique and patient selection during the time. In this study, we aimed to share the long-term outcomes of LAFT and technical tips of the procedure in our patient series.


Data of 100 patients with fistula-in-ano who underwent LAFT were retrospectively retrieved from a prospectively maintained database. This study was approved by the institutional review board. All of the procedures were performed by the same surgeon, and all of the patients were operated by using radial emitting laser probes of 3 different makes (FiLaC, Biolitec Biomedical Technology GmbH, Jena, Germany; Diomax, KLS Martin GmbH + Co. KG, Germany; neoV 1470, neoLaser, Caesarea, Israel).

Patient Selection Criteria and the Study Population

For the first 20 patients, all consecutive anal fistula patients underwent LAFT. Then, we realized that patients with underlying abscess through the fistula tract were associated with early failure of the procedure. The rest of the patients underwent preoperative MRI, and LAFT was performed after drainage in patients with abscess formation. However, we experienced that the success rate of the LAFT was low in patients with short and superficial fistula tract (posterior intersphincteric fistula originating form chronic anal fissure, superficial fistulas that may be treated with simple fistulotomy, short fistula tract), and we expanded the exclusion criteria.

The first 50 patients had been enrolled in our initial study. Later the rest of the patients were selected based on the initial experience from that study. All of the patients with fistula-in-ano were candidates for LAFT, whereas exclusion criteria were as follows:

  • Patients who were candidates for simple fistulotomy (patients with subcutaneous fistula and transsphincteric fistula involving <30% of the external sphincter)
  • Patients who had perianal abscess or sepsis with perianal fistula
  • Patients with IBD, particularly Crohn’s disease
  • Patients with intersphincteric fistula tracts <2 cm
  • Patients with posterior intersphincteric fistula originating from chronic anal fissure

All of the patients underwent MRI scan, with the exception of first 20 patients, to rule out underlying perianal abscess associated with the fistula tract. Patients with MRI-proven abscess had a drainage seton placed first, and then the success of the treatment was reassessed with control MRI scan. Patient demographics, the types of fistulas (determined using Parks’ classification7), the amount of energy used to seal the tracts, and the patient follow-ups were documented.

Surgical Technique for LAFT

A probe housing a 15-watt laser emitting at a wavelength of 1470 nm and an energy level of 100 to 120 joule/cm was applied to patients with fistula-in-ano under general anesthesia. This probe was a very thin, radial laser-emitting, flexible probe that could easily be inserted through the fistulas. The laser beams from the 2-cm tip produced heat energy that dissipated over a few millimeters, “burning” the contents of the fistula tract without harming the surrounding muscle fibers of the sphincters.

At the first step, external and internal openings of the fistula tract were examined during the anoscopic evaluation, and the fistula tract was gently probed. As it was described in our previously published study, we performed curettage of the fistula tract by using a plastic cytology brush.3 The laser probe then inserted into the fistula tract via external opening until the tip of the probe was located at the 1 or 2 mm beyond the internal opening. Energy was then applied as the laser probe was withdrawn through the external opening at a speed of 1 cm/6 seconds. During the application of the energy, letting the laser probe pass spontaneously through the fistula tract as it sealed the tract yielded the desired withdrawal speed. A gentle withdrawal of the probe for a few centimeters and then pushing it again toward the inner opening was sufficient to remove any dead space in the tract. After every 3 shots, the laser probe was removed and cleaned with hydrogen peroxide–soaked gauze to prevent charcoaling of the probe’s tip. Energy application was stopped when the tip of the probe was a few millimeters beyond the external opening. No sutures were placed at the internal or external openings, and no dressings or topical medications were used.

A follow-up office visit after LAFT was at postoperative week 3 or 4. Patients without complaints were not routinely followed up after the first visit unless they had wound healing problems in the anorectal examination. A phone call interview was scheduled at postoperative week 6 or 8 for the early assessment of procedural success.

Follow-up Data

Data regarding long-term success of the procedure were obtained by face-to-face or phone call interviews. Patients were classified based on 4 different situations:

  1. Overall complete healing (no discharge, no symptoms, fibrotic scar on skin where previously external opening was present)
  2. No healing (no improvement in the fistula after the procedure)
  3. Partial healing with minimal drainage and symptoms
  4. Recurrence at another site unrelated to the fistula treated at the original surgery

All patients reporting other than overall complete healing were defined as failure. Patients with persistent or painful symptomatic drainage were examined and underwent MRI scanning. Those patients underwent further treatment, and those secondary operations were also reviewed. Quantitative data were reported as median (range), and categorical data are presented as patient numbers with percentages.


The total number of patients who have undergone surgery for perianal fistula was 663 during the study period (2012–2016). LAFT was only used in 100 patients (15.1%). The flow chart regarding the success rate of LAFT is presented in Figure 1. Patient demographic and characteristics are shown in Table 1. There were no short-term complications. All of the patients were discharged the same day or the day after surgery. Median number of days required to return to normal activities was 3 days (range, 2–12 d), and the median number of days for cease of the symptoms attributed to fistula was 28 days (range, 20–38 d) after successful procedures. Thirty-six patients were interviewed at the outpatient clinic, and the others were interviewed by phone.

Patient demographics and characteristics
Flow chart regarding the success rate of laser ablation of fistula tract (LAFT).

The initial success rate was 82% in our previous study including 50 patients; however, this rate decreased to 54% after a median follow-up time of 64 months (range, 53–75 mo). On the other hand, the success rate increased up to 70% in the second 50-patient group. When the whole study population was considered, the overall success rate was 62% in a median follow-up time of 48 months (range, 6–56 mo). Intersphincteric fistulas were associated with the higher recurrence rate (Table 2).

Comparison of failed and healed patients with LAFT

In addition, patients were queried for the satisfaction with their procedure for a scale from 0 to 10 (0 = unhappy, 10 = excellent). In total, 81 patients replied to the question, and the remaining 19 patients reported being unhappy with the procedure. The median satisfaction score was 7 (range, 0–10). It was 6 (range, 0–10) and 9 (range, 0-10) for the first and second 50 patients.

In total, LAFT failed to treat fistula-in-ano in 38 patients. There were 7 patients who did not experience any improvement in the anal fistulas. Those were within the first 20 patients of the study group. One of them underwent mucosal advancement flap procedure, and the others were treated with fistulotomy. Five patients experienced another fistula in the perianal region other than the treated tract. Three of them were proven to have had missed horseshoe fistulas, and other 2 patients had transsphincteric fistulas treated with fistulotomy.

The remaining 26 patients showed improvement for some degree but had persistent discharge. All of the internal openings were healed in these patients, and fistulas had turned into sinuses. Repeat LAFT procedure was performed in 12 of those patients, of whom 10 were healed and the remaining 2 required excision of the subcutaneous short sinuses. The remaining 14 patients were treated with sinus excision. None of the patients in this study group experienced permanent major or minor anal incontinence.


This study showed that LAFT is a sphincter-saving treatment modality offering acceptable success rate and patient satisfaction for the surgical management of fistula-in-ano. Overall success rate was 62% without any incontinence issues in a median follow-up time of 48 months (range, 6–56 mo). Another important finding of this study was improving long-term success rate and patient satisfaction with the increasing experience of the surgical team.

During the study period, only 15.1% of all patients who underwent surgery for fistula-in-ano had LAFT performed. After treating 100 patients with laser, we think the following indications are associated with high likelihood of failure: intersphincteric fistulas, short fistula tract, fistulas originated from posteriorly located chronic anal fissures, fistulas with anterior external openings in women, fistulas originated from inadequately drained Bartholin’s abscesses, and Crohn’s-associated fistulas. Another factor associated with poor outcomes is the presence of an abscess related to the fistula tract. We recommend MRI for diagnosis of abscess in suspicious cases and placement of drainage seton first for those patients. When the abscess is adequately drained, then LAFT can be performed.

Prolonged discharge from the external opening was another frequent problem in our patients who underwent LAFT. There were 26 patients experiencing persistent discharge. We observed that the internal openings were healed in all of those patients, but there were subcutaneous sinuses. The mechanism of this problem may be the early closure of the external opening of the fistula. Laser ablation starts from the internal opening. The fistula tract is surrounded with sphincter muscle fibers and then soft tissue under the external opening. We observed that healing of the fistula tract with laser ablation is faster and stronger within the sphincter muscle fibers compared with soft tissue. The sinus locates under the external opening, in the subcutaneous soft tissue. Thus, we recommend excision of the skin around the external opening during LAFT to avoid early closure of the external opening and development of subcutaneous sinus.

LAFT is not a technically complicated procedure and may be successfully performed by surgeons who have experience regarding conventional anal fistula procedures. The technique is simply based on probing the fistula tract with the laser probe and ablation of the tract by radially emitted heat energy. We believe that patient selection is more important than the learning curve of the surgeon in terms of success rate of LAFT procedure. On the other hand, there are some technical tips, such as widening the external opening of the fistula, which may suggest the presence of a learning curve. We believe that the lessons learned from the first 50 patients increased the success of LAFT in the second 50 patients. On the other hand, longer follow-up time for the first 50 patients may be a factor associated with the lower success rate.

There are several studies reported long-term outcomes of LAFT, and the rates varied from 40% to 71%.4–6 The variability of success rates reflects the importance of patient selection for LAFT. Terzi et al6 treated 103 consecutive anal fistula patients with LAFT without performing a previous drainage procedure or imaging study for ruling out the presence of abscess. Their success rate was 40%, and exclusion criteria were anovaginal fistula, IBD, malignancy, and perianal tuberculosis. On the other hand, Giamundo et al5 reported a success rate of 71%. They reported that seton placement may facilitate outcomes by ensuring effective drainage, and seton may be used as a guide during the laser fiber insertion. Similarly, Wilhelm et al4 reported a 64% success rate and suggest that the use of seton and 2-stage technique may improve the success of LAFT. Data obtained from these studies suggest that performing LAFT in every patient with fistula-in-ano will obviously result in lower success rate. Our experience from this patient series is comparable with the literature. The presence of abscess along the fistula tract requires effective drainage before proceeding with LAFT. On the other hand, the main strength of the present study is its longer follow-up time compared with the other reports studying the long-term outcomes of LAFT.

Another key issue increasing the success rate of LAFT may be good understanding of the anatomy of the anal canal and fistula tract. Radiologic imaging studies, especially endoanal ultrasonography and MRI, are the mostly used modalities to understand the course of the fistula tract. Researchers study for enhancing the anal fistula imaging, and improvements such as 3-dimensional MRI visualization of fistula-in-ano are promising.8 Video-assisted anal fistula treatment (VAAFT) is a novel method including 2 steps: diagnosis and treatment.9,10 VAAFT allows real-time visualization of the fistula tract with a fistuloscope. A recent meta-analysis reported that the recurrence after VAAFT was associated with previous fistula surgery and the method for internal opening closure.11 Our results showed that LAFT is very good at internal opening closure. Combining the diagnostic phase of VAAFT with LAFT in the therapeutic phase may improve the success rate of both techniques. However, additional studies are needed.

The retrospective nature of this study is its main limitation. Other limitations consist of phone interview for follow-up of the majority of the patients, single-institution data, the relatively small number of patients, and summarizing the success rate with a simple fraction that may mislead estimation of the success rate. However, the long follow-up time gives our study its clinical value.

The results of the present study confirm that selective use of LAFT is associated with acceptable success rates. The success rate may be affected by the surgeons’ experience and avoiding LAFT in patients who are not good candidates for the technique: intersphincteric fistulas, short fistula tract, fistulas originated from chronic anal fissures, fistulas with anterior external openings in women, fistulas originated from inadequately drained Bartholin’s abscesses, and Crohn’s-associated fistulas. LAFT may be used as a first-line sphincter-sparing technique in the treatment of fistula-in-ano. Its cost may limit its use, particularly in developing countries. As a conclusion, there is not a miraculous treatment for fistula-in-ano. The key for success in anal fistula surgery may be good understanding of the anatomy of the anal canal regardless of the technique selected.


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Ablation; Fistula-in-ano; Laser

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