Lessons learned from an audit of 1250 anal fistula patients operated at a single center: A retrospective review

Table 6 Anal fistula classification

Classification	Parks	St James University Hospital	GARG
Grade I	Intersphincteric	Intersphincteric- linear	Low fistula- single tract (intersphincteric or transsphincteric)
Grade II	Transsphincteric	Intersphincteric-multiple tracts or associated abscess	Low fistula- multiple tracts or associated abscess or horseshoe tract (intersphincteric or transsphincteric)
Grade III	Suprasphincteric	Transsphincteric- linear	High fistula-single tract (intersphincteric or transsphincteric) or anterior fistula in a female or associated comorbidities1
Grade IV	Extrasphincteric	Transsphincteric-multiple tract or associated abscess	High fistula- multiple tracts or associated abscess or horseshoe tract (transsphincteric)
Grade V	NA	Supralevator or translevator/extrasphincteric	Suprasphincteric or supralevator or extrasphincteric

¹Crohn’s disease, sphincter injury or post radiation exposure. Low fistula- involves < 1/3 of the external sphincter; high fistula-involves > 1/3 of the external sphincter. NA: Not applicable.