A fistula is an abnormal connection of epithelial tissue - the type of tissue that lines the cavities and surfaces of anatomical structures. They are usually the result of trauma or surgery, but can also come about because of infection or inflammation. Although they are generally treated as a pathological condition, they can also be deliberately created by a physician for therapeutic purposes. They can appear throughout the body in just about any type of epithelial tissue.
A fistula is usually treated with surgery combined with antibiotic therapy.