- Anal glands in intersphincteric space
- Drain via anal sinuses onto dentate line
- Sinuses block with debris
- Impaired gland drainage
- Stasis
- Infection
- Abscess
- If abscess cannot drain back into the anal canal then slow increase in pressure until drain by another path
- perianal/subcutaneous, intersphincteric, ischioanal and supralevator
- This path can then either heal or become Epithelialised and a fistula