This is an anterior anal fistula. In most cases there is no underlying condition but it can occur in Crohn's disease, TB, anal carcinoma, HIV, etc. Investigations would include proctoscopy, flexible sigmoidoscopy, anal ultrasound, and MRI scan can be useful in chronic cases. Standard surgical treatment involves laying open of the fistula, taking care not to injure the anal sphincter muscles. Chronic fistula is managed by insertion of a Seton suture through the tract. This can either be removed after 2 months or, alternatively, tightened progressively until it erodes out through the skin.