By Dr Ananya Mandal, MD
A fistula is an abnormal connection that forms between two organs or vessels that are lined with epithelial cells. Fistulas are generally the result of a disease condition but artificial fistulas may also be surgically created for therapy.
Examples of naturally occurring fistulas are those that form between the anus and an opening in the skin (anal fistula) or between the intestine and the vagina (enterovaginal fistula). An artificial fistula may be created, for example, between an artery and vein (arteriovenous fistula) when a person needs renal dialysis.
Structure of a fistula
A fistula is a tube like structure that connects two surfaces. The fistula may form an opening in the skin, as with anal fistulas when the fistula forms between the rectum and the skin, forming an alternative pathway for the excretion of fecal materials.
Fistulas may also form between the rectum and the vagina and this is called a rectovaginal fistula. Although fistulas are usually caused by injury or surgery, they may also form after an infection has led to severe inflammation.
Some common types of fistulas include:
A blind fistula which forms a tube that opens only at one end and is closed at the other. These may turn into complete fistulas if left untreated.
An incomplete fistula, which has an only an external opening.
A complete fistula which has two openings, one of which is internal and the other external.
A horseshoe fistula describes a U-shaped connection formed between two external openings on both sides of the anus.
Reviewed by Sally Robertson, BSc