A fistula (plural: fistulas or fistulae -li,_-lai; from Latin fistula, "tube, pipe") in anatomy is an abnormal connection between two hollow spaces (technically, two epithelialized surfaces), such as blood vessels, intestines, or other hollow organs. Types of fistula can be described by their location. Anal fistulas connect the anal canal and the perianal skin. Anovaginal or rectovaginal fistulas occur when a hole develops between the anus or rectum and the vagina. Colovaginal fistulas occur between the colon and the vagina. Urinary tract fistulas are abnormal openings within the urinary tract or an abnormal connection between the urinary tract and another organ such as between the bladder and the uterus in a vesicouterine fistula, between the bladder and the vagina in a vesicovaginal fistula, and between the urethra and the vagina in urethrovaginal fistula. When occurring between two parts of the intestine, it is known as an enteroenteral fistula, between the small intestine and the skin as an enterocutaneous fistula, and between the colon and the skin as a colocutaneous fistula.
Fistulas can result from an infection or inflammation, injury or surgery. Fistulas are sometimes surgically created as part of a treatment, for example arteriovenous fistulas for hemodialysis.
Treatment for fistula varies depending on the cause and extent of the fistula, but often involves surgical intervention combined with antibiotic therapy. In some cases the fistula is temporarily covered using a fibrin glue or plug. Catheters may be required to drain a fistula.
Globally, every year between 50,000 and 100,000 women are affected by fistula relating to childbirth. In botany, the term is most common in its adjectival forms, where it is used in binomial names to refer to species that are distinguished by hollow or tubular structures. Monarda fistulosa, for example, has tubular flowers. The term was first used in the 14th century.
A fistula is an abnormal connection between vessels or organs that do not usually connect.