title: The surgical anatomy and etiology of gastrointestinal fistulas.
abstract: BACKGROUND
  Fistulas are abnormal communications between two epithelial surfaces, either between two portions of the intestine, between the intestine and some other hollow viscus, or between the intestine and the skin of the abdominal wall. The etiology of intestinal fistulas is in most cases a result of multiple contributing factors. Despite significant advances in their management over the past decades, intestinal fistulas remain a major clinical problem, with a high overall mortality rate of up to 30% due to the high rate of complications. This paper aims to describe classification systems based on the anatomy, physiology and etiology that may be helpful in the clinical management of intestinal fistulas.
  
  
  METHODS
  On the basis of anatomical differences, fistulas can be classified based by the site of origin, by site of their openings, or as simple or complex. Physiologic classification as low, moderate or high output fistulas is most useful for the non-surgical approach. Concerning the etiology, we classified the possible causes as (postoperative) trauma, inflammation, infection, malignancy, radiation injury or congenital.
  
  
  CONCLUSIONS
  Fistula formation can cause a number of serious or debilitating complications ranging from disturbance of fluid and electrolyte balance to sepsis and even death. They still remain an important complication following gastrointestinal surgery.
authors.affiliation: Department of Surgery, Section for Surgical Research, Medical University of Graz, Auenbruggerplatz 29, 8036, Graz, Austria.
authors.forename: J
authors.initials: J
authors.lastname: Pfeifer
authors.affiliation: Department of Surgery, Section for Surgical Research, Medical University of Graz, Auenbruggerplatz 29, 8036, Graz, Austria.
authors.forename: G
authors.initials: G
authors.lastname: Tomasch
authors.affiliation: Department of Surgery, Section for Surgical Research, Medical University of Graz, Auenbruggerplatz 29, 8036, Graz, Austria. selman.uranues@medunigraz.at.
authors.forename: S
authors.initials: S
authors.lastname: Uranues
keywords: Anatomy; Etiology; Fistula; Gastrointestinal fistula
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