Fistula is an abnormal connection caused by injury or surgery. The connection is between two hollow spaces like blood vessels, intestines or other hollow organs. They may also result in infection or inflammation.

Common symptoms of anal fistulas are
Pain and swelling in the anus
Pain in bowel movements
Bloody or foul smelling pus from the opening around the anus
Irritation of the skin around the anus
Fever, feeling extremely chilled and fatigue are other common symptoms found in anal fistula.

Diagnosis of fistula:
Physical examination is done to diagnose the area near the anus. In this method doctors look inside the external opening of the anal skin to see if there is any infection. Other diagnosis is done through ultrasound and MRI scan of the anal area. Blood tests and X-rays are done to observe the condition near the anus.

Treatment and Recovery:
Surgery, performed by a colon and rectal specialist, is usually necessary to manage an anal fistula. During surgery, the physician will assess the depth and extent of the fistula tract. Most fistulas are treated with a fistulotomy, in which the skin and muscle over the tunnel are cut open, converting it into an open groove. This will allow the fistula tract to heal from the inside out. A more complex fistula may require placement of a special drain—a sexton—for at least six weeks, after which a definitive surgical repair is done. Fistula surgery is generally done on an outpatient basis. Very large or deep fistula tunnels may require a short hospital stay.