About the disease :
Fistula indicates chronic process of Peri-anal abscess which is an acute inflammatory event. It is defined as an abnormal connection between the epithelialised surface of the anal canal and (usually) the peri-anal skin. Anal fistula originates 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.
Symptoms & Diagnosis :-
Patients with a fistula -in-ano will recount a history of an abscess that has been drained surgically or drained spontaneously. In addition patients will complain of drainage, bleeding, pain with defecation or decrease in pain with drainage. Diagnosis is by examination, either in an outpatient setting or under anesthesia (referred to as EUA - Examination under Anaesthesia). The examination can be an anoscopy.