Anal fistula, or fistula-in-ano, is an abnormal connection between the epithelialised surface of the anal canal and (usually) the perianal skin.
Anal fistulae originate from the anal glands, which are located between the two layers of the anal sphincters and which drain into the anal canal. If the outlet of these glands becomes blocked, an abscess can form which can eventually point to the skin surface. The tract formed by this process is the fistula.
Abscesses can recur if the fistula seals over, allowing the accumulation of pus. It then points to the surface again, and the process repeats.
Anal fistulae can present with many different symptoms:
- Discharge - either bloody or purulent
- Pruritus ani - itching
- Systemic symptoms if abscess becomes infected
Involves usually surgical procedures