Anal Fistula Laser Closure: the length of fistula is the Achilles' heel

Laser closure is a novel sphincter-saving technique for the treatment of anal fistula. The aim of this study was to report middle term results of laser treatment without closure of the internal orifice and to identify prognostic factors to improve selection criteria and maximize healing.

A retrospective observational study was conducted on patients treated with laser for transphinteric anal fistula. A diode laser emitting laser energy of 12W at a wavelength of 1470 nm was used. The relationship between fistula healing and age, sex, previous fistula surgery, location of fistula, and length of fistula tract was investigated. A successful outcome was defined by the complete healing of the surgical wound and external opening for at least 6 months.

Thirty patients (16 males, median age 52 years, range 26-72 years) underwent laser fistula closure between January 2015 and December 2016. Cure was achieved in 10 patients (33.3%). The mean follow-up was 11.30 months (range 6-24 months). Patients with persistent or recurrent fistula were offered repeat surgery. Eventually 4 underwent laser treatment once more. Two patients were cured leading to an overall healing rate of 40% (12 out of 30). Only 4 minor complications occurred (13.3%). No worsening of anal continence was registered. Only fistula length had a statistically significant correlation with successful treatment. Fistula tracts shorter than 30 mm were associated with a primary healing rate of 58.3% while tracts longer than 30 mm were cured in only 16.6% of cases (p < 0.02).

Laser closure is a safe and effective treatment for transphinteric anal fistula. The fistula length is the only significant prognostic factor when closing anal fistulas exclusively with laser: shorter fistulas have a better outcome.