*7.2.1 No standardized approach*

Conventionally, several techniques were described in treating fistula during acute abscess stage. For perianal and ischioanal abscesses with identifiable fistula tract, fistulotomy, fistulectomy and cutting seton were used [19, 24–26]. Internal sphincterotomy was reported for intersphincteric abscess [6, 13]. Oliver reports performing immediate fistulotomy only for low transphincteric, intersphincteric and subcutaneous type, with recurrence rate of 5% [28].

#### *7.2.2 Difficulty in localizing internal opening*

A meta-analysis in 2006 analyzed 5 studies with a total of 405 patients showed that internal opening is not found in 10–17% of cases [24]. Inability to locate internal opening leads to higher recurrence rate as the source of infected anal crypt is not dealt with. Recurrence rate increased from 5–29% when internal opening was not found [28]. Imaging modalities are not readily available in cases of acute abscess.

#### *7.2.3 Risk of incontinence*

The same meta-analysis reported that sphincter-cutting procedures like fistulotomy and cutting seton during acute abscess is associated with 2-fold increase of risk of fecal incontinence to flatus and soiling. Severe incontinence rate was reported up ranging from 0 to 40%, although sample sizes for most studies were small [24].

### **7.3 Feasibility**

The principles of treating acute fistulous abscess were laid down by McElwain:


3.Create a superficial external drainage for abscess beyond the external sphincter [19] – drainage of extrasphincteric abscesses

This author adds another 2 important principles:


In line with sphincter preservation as an important principle, a recent prospective study showed promising results utilizing sphincter preserving techniques for drainage and definitive treatment of fistulous anorectal abscess [29]. 86 patients with anorectal abscesses were operated by a single surgeon with intention of definitive single stage surgery and preservation of sphincter muscles. Using Rojanasakul's Natural Patterns of Anorectal Abscess and Fistula classification as guide, this study proposes 2 important steps: 1) Drainage of the perianal abscess at its most bulging point, 2) Exploration of the intersphincteric space to locate internal opening and intersphincteric tract/abscess. Internal opening was found in 95% of cases and intersphincteric tract was found in 77% of cases. Intersphincteric tract is treated with ligation as per LIFT procedure [4], whereas intersphincteric abscess were drained with suture closure of internal opening. Intersphincteric exploration wound is loosely closed with tube drains to promote drainage and secondary healing. This method reported overall healing rate of 83%, where the best results is obtained if intersphincteric tract is well formed. There were no cases of post-op incontinence. The remaining 17% non-healing group went on to elective surgery for definitive surgery of chronic fistula [29].

It is well known that in patients with anorectal abscesses undergoing simple drainage, 2/3 will progress to chronic fistula [27]. Definitive treatment of fistula may reduce the incidence of chronic fistula to an estimated below 30% based on recent evidence [28, 29]. With emerging sphincter preserving approaches, guided by our understanding of patterns of infection spread and imaging modalities, we are better equipped to approach acute fistulous abscesses with intention of single stage surgery.

### **8. Emerging concepts in managing cryptoglandular anal fistulas**

Principle of surgical treatment of chronic fistula-in-ano should include the following:


categories, thereby assessing its suitability for specific fistula types and adherence to the above principles.
