Fistula: An abnormal passageway in the body. The fistula may go from the body surface into a blind pouch or into an internal organ or go between two internal organs.?For a common example, an anal fistula has an opening in the skin near the?anus?that leads into a blind pouch or may connect through a tunnel with the?rectal?canal.?For a rare example, a gastropericardial fistula is a passageway between the?stomach and the?pericardial sac?(that surrounds the heart). There are numerous types of fistulas. They are usually designated by the organs or parts they connect (anovaginal, bronchoesophageal, etc.).
