An abnormal, narrow channel leading from some natural cavity – such as the duct of a gland, or the interior of the bowels – to the surface. Alternatively, a fistula may be a communication between two such cavities where none should exist – as, for example, a direct communication between the bladder and bowel.
Fistulas may either be congenital or develop as a result of injury or infection. A SALIVARY fistula may develop between the salivary gland and the outside of the cheek because of a blockage of the duct from the gland to the mouth. A urinary fistula may be one consequence of a fracture of the PELVIS which has damaged the URETHRA. Fistulas of the anus are one of the most common forms, usually the result of infection and ABSCESS formation.
As a rule, a fistula may be difficult to close, especially after it has persisted for some time. The treatment consists in an operation to restore the natural channel and, if this can be done, the fistula heals quickly under simple dressings.