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Inflammatory Bowel Disease: Intestinal Problems (cont.)

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What are intestinal fistulas?

Intestinal fistulas are tubular connections between the bowel and other organs or the skin. Fistulas form when inflammation extends through all of the layers of the bowel and then proceeds to tunnel through the layers of other tissues. Accordingly, fistulas are much more common in Crohn's disease than in ulcerative colitis. (In the latter, as you recall, the inflammation is confined to the inner lining of the large intestine.) Fistulas often are multiple. They may connect the bowel to other loops of the bowel (enteroenteric fistulas), to the abdominal wall (enterocutaneous), to the skin around the anus (perianal), and to other internal locations such as the urinary bladder (enterovesical), vagina (enterovaginal), muscles, and scrotum.

In Crohn's disease patients, fistulas may form in conjunction with intestinal strictures. One reason for this association is that both fistulas and strictures can begin with inflammation of the entire thickness of the bowel wall (transmural inflammation). Subsequent scarring (fibrosis) causes strictures while continuing inflammation and tissue destruction leads to the fistulas. A stricture can also help create a fistula. As already mentioned, a perforation of the intestine can occur above an obstructing stricture. The perforation can create a tract outside of the bowel wall. A fistula then may develop in this tract.

What symptoms do fistulas cause and how are they diagnosed and treated?

Intestinal fistula symptoms

Some fistulas, especially those that connect adjacent loops of bowel, may not cause significant symptoms. Other fistulas, however, can cause significant abdominal pain and external drainage, or create a bypass of a large segment of intestine. Such a bypass can occur when a fistula connects one part of the bowel to another part that is further down the intestinal tract. The fistula thereby creates a new route for the intestinal contents. This new route bypasses the segment of intestine between the fistula's upper and lower connections to the intestine. Sometimes, fistulas can open and close sporadically and unevenly. Thus, for example, the outside of a fistula might heal before the inside of the fistula. Should this occur, the bowel contents can accumulate in the fistulous tract and result in a pocket of infection and pus (abscess). An abscess may be quite painful and can be dangerous, especially if the infection spreads to the bloodstream.

Intestinal fistula diagnosis

Fistulas sometimes are difficult to detect. Although the outside opening of a fistula may be simple to see, the inside opening that is connected to the bowel may not be easy to locate. The reason for this difficulty is that fistulas from the bowel can have long, winding tunnels that finally lead to the skin or an internal organ. Endoscopy might detect the internal opening of a fistula, but it can easily be missed. Sometimes, a small bowel barium X-ray will locate a fistula. Often, however, an exam under general anesthesia may be required to fully examine areas that have fistulas, especially around the anus and vagina.

Intestinal fistula treatment

Intestinal fistulas that do not cause symptoms often require no treatment. Fistulas that cause significant symptoms, however, usually require treatment, although they are frequently difficult to heal.

Fistulas located around the anus (perianal) sometimes can be improved by treatment with the antibiotics, metronidazole (Flagyl) or ciprofloxacin (Cipro). In response to the antibiotics, some of these fistulas even close completely. Also, treatment with the immunosuppressive medications, azathioprine or 6MP, improves fistulas located around the anus (perianal) in almost two thirds of patients, including complete healing in one third. More recently, the new drug infliximab (Remicade), which is an antibody to one of the body's inflammation-inducing chemicals, has been shown to produce very similar results. Remember, however, that infliximab might worsen strictures, which, as mentioned, can sometimes be associated with fistulas.

When medications for the treatment of fistulas are discontinued, they usually re-open within 6 months to a year. Steroids do not heal fistulas and should not be used for this purpose. Other medications that suppress the immune system, such as cyclosporine or tacrolimus (FK506 or Prograf), are currently being studied for the treatment of fistulas. Sometimes, resting the bowel by feeding the patient solely with total parenteral (intravenous) nutrition (TPN), and thus nothing by mouth, is required to treat fistulas. Even if these fistulas heal in response to the TPN, they commonly recur when eating is resumed.

Fistulas sometimes require surgery. For example, when fistulas around the anus become very severe, they can interfere with the patient's ability to control bowel movements (continence). In this situation, the surgeon might make an opening (ostomy) to the skin from the bowel above the fistulas. The intestinal contents are thereby diverted away from the fistulas. Occasionally, when absolutely necessary, intestinal fistulas are surgically removed, usually along with the involved segment of the bowel. Fistulas from the intestine to the bladder or vagina are frequently very difficult to close with medical treatment alone and often require surgery.

Medically Reviewed by a Doctor on 8/5/2016


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