| Grade |
Description |
| 0 |
Normal appearances |
| 1 |
Simple linear intersphincteric fistula |
| 2 |
Intersphincteric fistula with intersphincteric abscess or secondary fistulous track |
| 3 |
Transsphincteric fistula |
| 4 |
Transsphincteric fistula with abscess or secondary track within the ischioanal or ischiorectal fossa |
| 5 |
Supralevator or translevator disease |