Inflammatory Bowel Disease: Intestinal Problems (cont.)
How do intestinal strictures form in
IBD?
When inflammation is present for a long time (chronic), it sometimes can
cause scarring (fibrosis). Scar tissue is typically not as flexible as healthy
tissue. Therefore, when fibrosis occurs in the intestines, the scarring may
narrow the width of the passageway (lumen) of the involved segments of the
bowel. These constricted areas are called strictures. The strictures may be mild
or severe, depending on how much they block the contents of the bowel from
passing through the narrowed area.
Crohn's disease is characterized by inflammation that
tends to involve the deeper layers of the intestines. Strictures, therefore, are
more commonly found in Crohn's disease than in ulcerative colitis. What is more, strictures in
Crohn's disease may be
found anywhere in the gut. Remember that the intestinal inflammation in
ulcerative colitis is
confined to the inner lining (mucosa) of the colon. Accordingly, in chronic
ulcerative colitis,
benign (meaning not malignant) strictures of the colon occur only rarely. In
fact, a narrowed segment of the colon in ulcerative colitis may well be caused by a colon cancer
rather than by a benign (non-cancerous), chronic inflammatory stricture.
What symptoms do intestinal strictures cause and how are they diagnosed?
Patients may not know that they have an intestinal stricture. The stricture may
not cause symptoms if it is not causing significant blockage (obstruction) of
the bowel. If a stricture is narrow enough to hinder the smooth passage of the
bowel contents, however, it may cause abdominal pain, cramps, and bloating
(distention). If the stricture causes an even more complete obstruction of the
bowel, patients may experience more severe pain, nausea, vomiting, and an
inability to pass stools.
An intestinal obstruction that is caused by a
stricture can also lead to perforation of the bowel. The bowel must increase the
strength of its contractions to push the intestinal contents through a narrowing
in the bowel. The contracting segment of the intestine above the stricture,
therefore, may experience an increased pressure. This pressure sometimes weakens
the bowel wall in that area, thereby causing the intestines to become abnormally
wide (dilated). If the pressure becomes too high, the bowel wall may then
rupture (perforate). This perforation can result in a severe infection of the
abdominal cavity (peritonitis), abscesses (collections of infection and pus),
and fistulas (tubular passageways originating from the bowel wall and connecting
to other organs or the skin). Strictures of the small bowel also can lead to
bacterial overgrowth, which is yet another intestinal complication of IBD.
Intestinal strictures of the small intestine may be diagnosed with a small bowel
follow-through (SBFT) x-ray. For this study, the patient swallows barium, which
outlines the inner lining of the small intestine. Thus, the x-ray can show the
width of the passageway, or lumen, of the intestine. Upper GI endoscopy (EGD)
and enteroscopy are also used for locating strictures in the small intestine.
For suspected strictures in the colon, barium can be inserted into the colon
(barium enema), followed by an x-ray to locate the strictures. Colonoscopy is
another diagnostic option.
How are intestinal strictures in IBD treated?
Intestinal strictures may be composed of a combination of scar tissue
(fibrosis) and tissue that is inflamed and, therefore, swollen. A logical and
sometimes effective treatment for these strictures, therefore, is medication to
decrease the inflammation. Some medications for IBD, such as infliximab,
however, may make some strictures worse. The reason is that these medications
may actually promote the formation of scar tissue during the healing process. If
the stricture is predominantly scar tissue and is only causing a mild narrowing,
symptoms may be controlled simply by changes in the diet. For example, the
patient should avoid high fiber foods, such as raw carrots, celery, beans,
seeds, nuts, fiber, bran, and dried fruit.
If the stricture is more severe and
can be reached and examined with an endoscope, it may be treated by stretching
(dilation) during the endoscopy. In this procedure, special instruments are used
through the endoscope to stretch open the stricture. Typically, however, this
procedure does not produce long lasting results.
Surgery sometimes is needed to
treat intestinal strictures. The operation may involve cutting out (resecting)
the entire narrowed segment of bowel, especially if it is a long stricture. More
recently, a more limited operation, called stricturoplasty, has been done. In
this procedure, the surgeon simply cuts open the strictured segment lengthwise
and then sews the tissue closed crosswise so as to enlarge the width of the
bowel's passageway (lumen). After surgery in Crohn's disease patients, medication still
should be taken to prevent inflammation from recurring, especially at the site
of the stricture. The reason for this recommendation is that after abdominal
operations, recurrent intestinal inflammation is a common problem in Crohn's
disease.
Furthermore, the risk of post-operative intestinal fistulas and abscesses is
increased in Crohn's disease patients. Therefore, only abdominal surgery that is absolutely
necessary should be done in patients with Crohn's disease.
Next: What are intestinal fistulas? »
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