**5.5 Garg's classification**

The most recent classification was introduced in 2017 and validated in 2020 with over 848 patients using combination of MRI study and intra-operative findings [12, 18]. This classification provided comprehensive and detailed grouping of anal fistula into 5 grades, from simple to complex grading (**Table 2**). In general, complexity was determined by low or high fistula, presence of multiple secondary tracts or collections. Intersphincteric and transphincteric fistulas were both recognized as simple if the fistula is low and safe for fistulotomy. This classification allows stratification of fistula-in-ano in a practical manner to guide their management strategies. Grade 1 and 2 fistulas were reported as safe to be treated with fistulotomy, whereas grade 3 to 5 requires more complex surgical strategy or expert referral (refer to **Table 2**) [12]. This method of stratification was validated to be safe. Following the Garg's new classification, patients underwent fistulotomy did not show significant changes in continence score post operatively [18]. However, this grading method relies heavily on MRI, which is not readily available in all


*\* Low transphincteric: <sup>&</sup>lt;1/3 of external sphincter involved. High transphincteric: <sup>&</sup>gt; 1/3 of external sphincter involved. ¥ Grade 1: Fistulotomy should be possible in almost all these fistulas (>95%). Grade 2: Fistulotomy should be possible in majority of these fistulas (>90%)*

#### **Table 2.**

*Garg's New Classification of Anal Fistulas (information extracted from Garg [18]).*

institutions. Furthermore, there are many subclassifications to remember and challenging complex type such as suprasphincteric, supralevator and extrasphincteric types, were group into a single category even though each have unique patterns.

A useful classification allows clinicians:


In general, most of the classifications above do not fulfill all 3 criteria above. Garg's classification was a significant improvement in categorizing, stratification and suggested treatment options for each grade. However, when faced with complex fistulas, there is still a general lack of understanding of its pathogenesis and optimal surgical treatment. This author believes, the step forward is to provide a more comprehensive treatment algorithm/guideline based on knowledge of natural patterns and progressions. To achieve this, the author believes classification based on natural patterns of cryptoglandular abscess and fistula will provide further insight.
