I read with great interest the article by Lalhruaizela [1] highlighting his experience with endofistula laser ablation (EFLA) in anal fistulas. The author reported a primary success rate of 67.7% and a secondary (overall) success rate of 80% in a cohort of 31 anal fistula patients. However, there are a couple of questions and pertinent points that merit discussion according to our experiences.

The author included only primary, simple low uncomplicated fistulas in the study and excluded high complex fistulas [1]. However, it was not precisely defined which fistulas were categorized as simple and which ones as complex. One patient with a suprasphincteric fistula was also included in the study. Suprasphincteric fistulas are high complex fistulas and are categorized as grade III by Garg [2] and grade V by the St. James’s University Hospital [2] and Garg classifications [2, 3].

Low fistulas are defined as those involving less than one-third of the external anal sphincter [2]. It is an established fact that fistulotomy is the gold standard for managing low simple fistulas [3]. A success rate of 98% to 100% can be achieved in low fistulas with minimal risk to continence [3]. Therefore, the management of low simple fistulas is almost a settled issue. However, fistulotomy is contraindicated in high fistulas (fistulas involving more than one-third of the external anal sphincter) due to the high risk of incontinence [3]. Therefore, what is urgently needed is to find a sphincter-saving procedure in high fistulas that would not cause a significant deterioration in continence.

Several new sphincter-saving procedures have been advocated in the last decade. These include the anal fistula plug, video-assisted anal fistula treatment (VAAFT), over-the-scope clip (OTSC), the FiXcision device (A.M.I), fistula laser closure (FiLaC; Biolitec), and EFLA [3, 4]. These procedures are device-dependent, expensive, and require a learning curve [4]. The primary reason and intention behind the innovation of these sphincter-saving procedures were to find a safe (minimal risk to continence) and effective procedure for high fistulas. Incidentally, almost all studies published to date have demonstrated moderate efficacy of these device-driven procedures in low simple fistulas (40%–70%), for which fistulotomy offers 95% to 100% healing rates [3]. To date, no studies have analyzed the efficacy of these newer procedures in a cohort of exclusively high complex fistulas [3]. This raises a question regarding their utility and exact place in the management of anal fistulas. Could it be a case of aggressive marketing by device manufacturing companies, a possibility that cannot be ruled out?

The latest understanding in the pathophysiology of complex anal fistulas underlines the importance of adequately managing sepsis in the intersphincteric space [5]. It has been highlighted that sepsis in the fistula tract in the intersphincteric space is like an “abscess in a closed space” [5]. An abscess, anywhere in the body, is not cured by simple aspiration or antibiotics. It requires drainage of the abscess cavity and ensured drainage in the postoperative period to facilitate healing by secondary intention [3, 5]. Therefore, deroofing of the abscess cavity is performed to achieve drainage in the postoperative period. These time-tested, well-known principles of abscess management need careful consideration in the management of complex anal fistulas.

Most complex anal fistulas have a degree of an intersphincteric component (fistula tract in the intersphincteric space). It becomes pertinent to deal effectively with this “abscess in a closed space” (fistula tract in the intersphincteric space) [3, 5]. If the fistula tract in the intersphincteric space is not managed properly, as happens with the use of an anal fistula plug, VAAFT, OTSC clip, FiXcision, FiLaC, or EFLA, then the chances of recurrence are quite high [3, 5]. If a fistula tract in the intersphincteric space is deroofed into the ischiorectal fossa, the external anal sphincter would be damaged, leading to a deterioration in continence [6]. Therefore, the most convenient and safest way is deroofing a fistula tract in the intersphincteric space into the anal canal through the transanal route, as is done in the transanal opening of the intersphincteric space (TROPIS) technique [5, 7, 8]. Therefore, the success rate of TROPIS is quite high (90%) in high complex anal fistulas [5, 7, 8]. A recent meta-analysis highlighted that of all sphincter-preserving procedures, TROPIS had the highest cure rate [9]. Fistulectomy with primary sphincter reconstruction also excises the fistula tract in the intersphincteric space and thus has a high success rate in high fistulas. Although ligation of intersphincteric fistula tract (LIFT) addresses and opens the fistula tract in the intersphincteric space, it does not ensure continuous drainage in the postoperative period (by deroofing) [4]. Therefore, LIFT has a moderate success rate in high complex fistulas [4, 10].

In summary, proper management of the fistula tract in the intersphincteric space had been largely ignored in the management of anal fistulas, and the emphasis had been entirely on the closure of the internal opening and management of external tracts. The opening of the fistula tract in the intersphincteric space was limited to the drainage of high intersphincteric abscesses and this was never extended to the routine management of high complex anal fistulas. Once this gap was addressed by the development of the TROPIS procedure, the success rate jumped markedly, with no significant deterioration in continence.