Crohn's Disease (cont.)
Adam Schoenfeld, MD
George Y. Wu, MD, PhD
In this Article
How is Crohn's disease diagnosed?
The diagnosis of Crohn's disease is suspected in patients with fever, abdominal pain and tenderness, diarrhea with or without bleeding, and anal diseases. Laboratory blood tests may show elevated white blood cell counts and sedimentation rates, both of which suggest infection or inflammation. Other blood tests may show low red blood cell counts (anemia), low blood proteins, and low body minerals, reflecting loss of these minerals due to chronic diarrhea.
Barium X-ray studies can be used to define the distribution, nature, and severity of the disease. Barium is a chalky material that is visible by X-ray and appears white on X-ray films. When barium is ingested orally (upper GI series) it fills the intestine, and pictures (X-rays) can be taken of the stomach and the small intestines. When barium is administered through the rectum (barium enema), pictures of the colon and the terminal ileum can be obtained. Barium X-rays can show ulcerations, narrowing, and, sometimes, fistulae of the bowel.
Direct visualization of the rectum and the large intestine can be accomplished with flexible viewing tubes (colonoscopes). Colonoscopy is more accurate than barium X-rays in detecting small ulcers or small areas of inflammation of the colon and terminal ileum. Colonoscopy also allows for small tissue samples (biopsies) to be taken and sent for examination under the microscope to confirm the diagnosis of Crohn's disease. Colonoscopy also is more accurate than barium X-rays in assessing the degree (activity) of inflammation.
Computerized axial tomography (CAT or CT) scanning is a computerized X-ray technique that allows imaging of the entire abdomen and pelvis. It can be especially helpful in detecting abscesses. Recently, CT and MRI enterography, imaging techniques which use oral contrast agents consisting of watery solutions with or without low concentrations of barium to provide more adequate luminal distension, have been reported to be superior in the evaluation of small bowel pathology in patients with Crohn's disease3.
Most recently, video capsule endoscopy (VCE) has also been added to the list of tests for diagnosing Crohn's disease. For video capsule endoscopy, a capsule containing a miniature video camera is swallowed. As the capsule travels through the small intestine, it sends video images of the lining of the small intestine to a receiver carried on a belt at the waist. The images are downloaded and then reviewed on a computer. The value of video capsule endoscopy is that it can identify the early, mild abnormalities of Crohn's disease. Video capsule endoscopy may be particularly useful when there is a strong suspicion of Crohn's disease but the barium X-rays are normal. (Barium X-rays are not as good at identifying early, mild Crohn's disease.) In a prospective blinded evaluation, video capsule endoscopy was demonstrated to be superior in its ability to detect small bowel pathology missed on small bowel radiographic studies and CT exams3.
Video capsule endoscopy should not be performed in patients who have obstruction of the small intestine. The capsule may get stuck behind the obstruction and make the obstruction worse. Doctors usually also are reluctant to perform video-capsule endoscopy for the same reason in patients who they suspect of having small intestinal strictures (narrowed segments of small intestine that can result from prior surgery, prior radiation, or chronic ulceration, for example, from Crohn's disease). There is also a theoretical concern for electrical interference between the capsule and implanted cardiac pacemakers and defibrillators; however, so far in a small-moderate number of patients with pacemakers or defibrillators who have undergone video capsule endoscopy there have been no problems.
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