A fistula is the communication between two epitheliums. In surgery, the most frequent cause is found between intra abdominal organs, such as the union of the stomach with the small intestine, the small intestine with the skin, the large intestine with the bladder or vagina and many other combinations.
The conditions can cause abdominal pain and the leakage of intestinal contents out of an atypical site.
Intestinal fistulas can be treated surgically and in some cases require highly specialized care.