Fistula

A fistula is an abnormal tunnel connecting two body cavities (such as the rectum and the vagina) or a body cavity to the skin (like the rectum to the outside of the body). One way a fistula may form is from an abscess--a pocket of pus in the body. The abscess may be constantly filling with body fluids such as stool or urine, which prevents healing. Eventually the fistula breaks through to the skin, another body cavity, or an organ. Fistulas are more common in Crohn's Disease than in ulcerative colitis. Approximately 30% of people with Crohn's Disease develop fistulas.

Types of Fistulas

Fistulas often occur in the area around the genitals and anus (known as the perineum). The four types of fistulas are:

• Enterocutaneous: This type of fistula is from the gut to the skin. It can be described as a passageway that progresses from the gut to the surgery site and then to the skin. An enterocutaneous fistula may be a complication of surgery.
  
• Enteroenteric or Enterocolic: This is a fistula that involves the large or small intestine.
  
• Enterovaginal: This is a fistula that goes to the vagina.
  
• Enterovesicular: This type of fistula goes to the bladder. These fistulas may result in frequent urinary tract infections, or the passage of gas from the urethra during urination.

Diagnosis

Fistulas, depending on their location, can be diagnosed by some of the diagnostic tests often used in IBD. Barium enema, colonoscopy, sigmoidoscopy, or an upper endoscopy may be used.

Another test, a fistulogram, may also be used. In this test, dye is injected into the fistula, and x-rays are taken. The dye helps the fistula to show up better on the x-rays. The dye is inserted into the rectum, similar to an enema, for fistulas that are in the rectum. The dye must be 'held' inside during the procedure. With a fistula that is to the outside of the body, the dye is put into the opening with a small tube. X-rays will be taken from several different angles, so a patient may have to change positions on the x-ray table. As with any other kind of x-ray, remaining still is important.

For a suspected enterovesicular (bladder) fistula, an intravenous pyelogram (IVP), another type of x-ray, is performed. Prepping for this test may include a clear liquid diet or fasting, because stool in the colon can obstruct the view of the bladder. The dye (contrast material) is injected into the arm, and several x-rays are taken.

Complications

A fistula may form an abscess when it closes, or if it becomes infected. An abscess is an infection inside a cavity in the body.

Treatment

Treatments for fistulas vary depending on their location and severity of symptoms. Medicinal treatments include Flagyl (an antibiotic), 6-MP (an immunosuppresant), or Remicade.

An enteral diet may be prescribed for enterovaginal, enterocutaneous, and enterovesicular fistulas. An enteral diet is liquidx that is taken by mouth or given through a feeding tube. These liquid nutrition formulas replace solid food and contain vital nutrients. With no solid food there is less stool passing through the anus, which helps the fistula to heal and maybe even close.

Fistulas that don't respond to any of the above therapies may require surgery. If the fistula is in a healthy part of the gut, it may be removed without taking out any part of the intestine. If the fistula is in a very diseased part of the bowel, a resection may have to be performed.

A resection may result in a temporary ileostomy. Stool is diverted through the ileostomy, giving the part of the intestine with the fistula time to heal. This type of surgery is most often done on rectovaginal or enterovesicular fistulas.

Prognosis

The location and severity of the fistula play a major role in determining treatment. With proper care, a fistula can be treated and healed and should not re-occur.