Preventing the recurrence of acute anorectal abscesses utilizing a loose seton: a pilot study

Introduction This pilot study aimed to document our results of treating anorectal abscesses with drainage plus loose seton for possible coexisting high fistulas or drainage plus fistulotomy for low tracts at the same operation. Methods Drainage plus fistulotomy were performed only in cases with subcutaneous mucosa, intersphincteric, or apparently low transsphincteric fistula tracts. For all other cases with high transsphincteric fistula or those with questionable sphincter involvement, a loose seton was placed through the tract. Drainage only was carried out in 17 patients. Results Twenty-three patients underwent drainage plus loose seton. Drainage plus fistulotomy were performed in four cases. None of the patients developed recurrent abscess during a follow-up of 12 months. Not surprisingly, the incontinence scores were similar pre and post-operatively (p=0.564). Only minor complications occurred in 4 cases (14.8 percent). Secondary interventions following loose seton were carried out in 13 patients (48.1 percent). At 12 months, drainage only was followed by 10 recurrences (58.8 percent; p<0.0001, compared with concomitant surgery). Conclusion Concomitant loose seton treatment of high fistula tracts associated with anorectal abscess prevents abscess recurrence without significant complications or disturbance of continence. Concomitant fistulotomy for associated low fistulas also aids in the same clinical outcome. Concomitant fistula treatment with the loose seton may suffice in treating the whole disease process in selected cases. Even in patients with high fistula tracts, the loose seton makes fistula surgery simpler with a mature tract. Abscess recurrence is high after drainage only.


Introduction
Concurrent definitive treatment of underlying fistulas at the time when the anorectal abscesses are drained is a controversial issue. Fistulain-ano can increase the likelihood of abscess recurrence which then requires repeat drainage. Even with no recurrent abscess, further interventions may be needed for fistula-related symptoms such as discharge or perianal soreness. Regarding the pathogenetic association of the crypto-glandular abscess and fistula, attempting to eliminate the whole disease process concomitantly with the drainage of the abscess might be a reasonable approach mainly because i) the development of recurrent abscesses and repeated surgical drainages may be prevented and ii) eventual fistula surgery with additional anesthesia may be omitted. However, drawbacks exist based on the suggestions that i) some abscesses will not recur or evolve to become a fistula and ii) a combined procedure has a greater risk of anal incontinence. Nevertheless, the persistent entity of anorectal abscess and fistula is a common problem contributing significantly to the daily surgical workload, as well as expenses, day off work, and quality of life [1].
In this respect, there are growing inclination and efforts to treat any coexisting fistula tract concomitantly with the drainage of the abscess.
Although about one-thirds of perianal abscesses were thought to be associated with fistula-in-ano [1][2][3], more recent studies aiming to detect any coexisting fistula tract have reported much higher rates (80-90 percent) of finding a fistula with a perianal abscess [4][5][6]. Two meta-analyses showed significant reductions in recurrence, persistent abscess/fistula or repeat surgery in favor of fistula surgery at the time of abscess incision and drainage (I&D) [7,8]. Even in children surgically treated for first-time perianal abscess, recurrence rates appear to be lowered by locating and treating coexisting fistulas [9].
Stratifying this group of patients, Oliver and coworkers recommended concomitant fistulotomy for subcutaneous, intersphincteric or low transsphincteric tracts, but not for high fistulas [6]. Likewise, the clinical practice guidelines of the American Society of Colon and Rectal Surgeons (ASCRS) have suggested that fistulotomy may be performed when a simple fistula is encountered during I&D [10]. This study aimed to document our results of treating anorectal abscesses with drainage plus loose seton for possible coexisting high or suspect fistula tracts or drainage plus fistulotomy for low fistulas at the same operation. Our rationale was to approach the surgical treatment of choice in anorectal abscesses which would offer the lowest recurrence without affecting continence.   Figure 4). Although most of these recurrences were treated by concomitant fistula surgery, they were not reinstated further in the study.

Discussion
The results of our study have suggested that identification and loose seton treatment of high fistula tracts associated with anorectal abscess prevents abscess recurrence without significant complications or disturbance of continence. Concomitant fistulotomy for associated Page number not for citation purposes 4 low fistulas also aids in the same clinical outcome. A fistula tract was identified in 93.1 percent of the cases. Although a draining seton has been suggested to be a safe and acceptable treatment as an alternative to 'primary' fistulotomy, our study is probably the first to present data in this setting [10]. The loose seton prevented abscess recurrences in all patient within the time limits. As expected, no specific complications or anal incontinence occurred. The literature and guidelines have been rather reluctant to suggest definitive fistula surgery together with abscess drainage [10,14]. The fact that concomitant fistula treatment has largely been limited to fistulotomy or cutting seton has contributed negatively to the development of this reasonable strategy. Although Read mentioned performing a primary fistulotomy for all their perianal abscesses if a fistula was found concomitantly, Hebjorn did the first controlled trial [2,4]. Their technique was not exactly synchronous drainage plus fistulotomy and the 40 percent rate of minor continence problems reported after CS put shade on a more liberal approach for many years. Oliver and coworkers randomized a large group of patients [6]; however, more than two-thirds of their patients surprisingly had subcutaneous or intersphincteric abscesses. This patient distribution is different to our findings and knowledge that anorectal abscesses are more common in the perianal and ischiorectal spaces, and less common in the intersphincteric, supralevator, and submucosal locations [2,15]. We noted a 58.8 percent rate of abscess recurrence in a year and this rate will probably increase in long term.

Conclusion
In conclusion, further controlled trials are inspired by the results of this study suggesting that: i) associated fistula tracts can be identified in the majority of cases with acute anorectal abscess; ii) loose seton treatment of high fistula tracts associated with anorectal abscess prevents abscess recurrence without complications or disturbance of continence. Concomitant fistulotomy for associated low fistulas also aids in similar clinical outcome; iii) concomitant fistula treatment with the loose seton may suffice in treating the whole disease process in selected cases; iv) after the inflammation resolves, the seton provides a mature and usually a more superficial tract. Therefore, an urgent, septic condition is converted to an elective one for tertiary centers; and v) abscess recurrence is high after I&D only.
What is known about this topic • Perianal abcess recurrence is possible due to untreated fistula if only simple drainage performed; • Combined surgery for the treatment of abcess and fistula at the same operation can cause fecal incontinence.

What this study adds
• Utilising a loose seton can prevent recurrence of abcess and avoids or fascilitates the fistulae surgery during follow up without major complications.

Authors' contributions
All authors contribute conception and design, acquisition of data, or analysis and interpretation of data. Reviewed during and contribute during draft writing and approved the final version.