What is Fistula ? (medical term)?

Fistula is an abnormal connection or passageway between organs or vessels that normally do not connect.

Causes

Various causes of fistula are:

* Diseases: Inflammatory bowel diseases, such as Crohn's disease and ulcerative colitis, are the leading causes of anorectal, enteroenteral, and enterocutaneous fistulas. A person with severe stage-3 hidradenitis suppurativa will also develop fistulas.

* Medical treatment: Complications from gallbladder surgery can lead to biliary fistula. Radiation therapy can lead to vesicovaginal fistula.

* Trauma: Head trauma can lead to perilymph fistulas, whereas trauma to other parts of the body can cause arteriovenous fistulas. Obstructed labor can lead to vesicovaginal and rectovaginal fistulas. Vesicovaginal and rectovaginal fistulas may also be caused by rape, in particular gang rape, as evidenced by the abnormally high number of women in conflict areas, such as that of the Second Congo War, who have suffered fistulae.


So many kind of Fistula look this site
http://en.wikipedia.org/wiki/Fistula#Typ...

In medicine, a fistula (pl. fistulas or fistulae) is an abnormal connection or passageway between organs or vessels that normally do not connect.

A fistula is an abnormal connection between an organ, vessel, or intestine and another structure. Fistulas are usually the result of injury or surgery. It can also result from infection or inflammation.

Inflammatory bowel disease, such as ulcerative colitis or Crohn's disease, is an example of a disease that leads to fistulas between one loop of intestine and another. Injury can lead to fistulas between arteries and veins.

The term fistula is also used to describe a loop (of either vein or GoreTex) that connects an artery to a vein. A patient who will need dialysis will often get a fistula creted so that dialysis access will be easier.