A fistula is an abnormal connection between two organs, typically in the gastrointestinal tract, urinary tract, or reproductive organs. The three types of fistula include anorectal, gastrointestinal, and urogenital. An anorectal fistula is a tunnel that forms between the anal canal and the skin around the anus, and is usually caused by an infection or an abscess. Gastrointestinal fistulas are abnormal connections between two parts of the digestive tract, such as the small intestine and the large intestine. Urogenital fistulas are connections between the urinary tract and reproductive organs, such as the bladder and the vagina. Depending on the type of fistula, treatments may include surgery, antibiotics, and lifestyle changes.