Intestinal fistulas are abnormal connections between parts of the intestine or between the intestine and other hollow organ, or even the body surface. They are frequent complications of local inflammatory diseases and they may significantly impair the life quality.
In general, intestinal fistulas can be divided into external (gut-body surface) and internal (gut-gut, gut-other organ).
Intestinal fistulas are channels that can arise during inflammatory processes in the abdominal cavity. They typically accompany the inflammatory autoimmune diseases known as the Crohn's disease and severe forms of diverticulitis (inflammation of the intestinal pouches – diverticuli). The fistulas may also occur in some forms of colon cancer. Inflammatory fistulas may develop after surgical intervention in the abdominal cavity and after local radiotherapy (radiation colitis). A fistula between the intestine and stomach may occur as a result of untreated peptic ulcer, which grows from the stomach wall into the intestine connecting these two organs.
Intestinal fistula can act as shortcut, which bypasses a part of the intestine. This can cause malabsorption of nutrients, diarrhea, weight loss and dehydration. In addition, the fistulas may lead the intestinal content, i.e. stool, to places it does not belong. Crohn’s disease is typically accompanied with perianal fistulas that open on the surface of the skin around the anus. The fistula may also breach the anal sphincter causing the incontinence of stool. Stool leakage causes local hygienic problems and increases risk of local purulent skin infections. However, the fistulas may lead not only to the body surface, but also to hollow organs such as the urinary bladder or vagina. In such case, the stool gets into the urinary or gynecological tract where it may cause smelly discharge and recurrent local infections. When the fistula connects the intestine with stomach, it causes a very unpleasant bad breath.
Schema shows two types of intestinal fistualas - perianal fistula protruding from the anus
on the surface of the body and fistula connecting the rectum with bladder
The presence of external fistula may be diagnosed by physical examination, when we see its opening. Internal fistulas can be visualized by various imaging methods (X-ray, computed tomography) with usage of contrast agents to observe the anatomy of a fistula and the location of its openings. The small intestine is well-examinable by CT enteroclysis. Upper gastrointestinal tract including the stomach and duodenum may be examined by upper GI endoscopy and the colon may be examined by colonoscopy.
The effective treatment of an intestinal fistula is often very difficult and must be strictly individual. Generally speaking, we have to try to treat the cause of fistula formation, for example the inflammatory activity of Crohn's disease. Infectious complications of fistulas should be treated by antibiotics and proper nutrition. In some cases it may be necessary to temporary replace the oral nutrition by parenteral nutrition (specific nutrient solutions administered intravenously) to allow the guts to rest and to facilitate the healing process. Under ideal circumstances, the fistulas heal themselves. When this does not happen, it is possibly to remove surgically either the fistulas, or even the affected part of the intestine. However, when the causative factor is not removed, the recurrence of fistulas is very probable.