Diagnosis
The doctor will take a history and perform a thorough physical examination. The disease is particularly difficult to diagnose in children. In children, IBD may be mistaken for an infection or even depression if other characteristic symptoms, such as bloody diarrhea and weight loss, are not present. Slow growth may be a key feature in making a diagnosis, particularly of Crohn's disease, in children.
Several laboratory tests may be performed:
- Blood tests are used for various purposes. An increased number of white blood cells may indicate the presence of inflammation. Blood tests are used to determine the presence of anemia and to measure liver enzymes. (They are abnormal in about 3% of ulcerative colitis patients.) New blood tests that measure certain antibodies may make it easier to differentiate Crohn's disease from ulcerative colitis in children.
- A stool sample is taken and examined for blood, infectious organisms, or both.
Procedures Used for Diagnosis
Standard Endoscopic Procedures. Flexible sigmoidoscopy and colonoscopy are procedures that involve snaking a fiberoptic tube called an endoscope through the rectum to view the lining of the colon. The doctor can also insert instruments through it to remove tissue samples.
- Sigmoidoscopy, which is used to examine only the rectum and left (sigmoid) colon, lasts about 10 minutes and is done without sedation. It may be mildly uncomfortable, but it is not painful.
- Colonoscopy allows a view of the entire colon and requires a sedative, but it is still performed on an outpatient basis. It is important in differentiating between Crohn's disease and ulcerative colitis and in screening for colon cancer.
The procedures may help the doctor to distinguish between ulcerative colitis and Crohn's disease, as well as other diseases. A variation called chromoendoscopy uses a blue stain during the process to reveal fine details on the intestinal lining. It might prove to be useful for identifying areas that may be precancerous and need to be biopsied.
Wireless Capsule Endoscopy. Wireless capsule endoscopy (WCE) is a new imaging approach that is very useful for diagnosing Crohn's disease. With WCE, the patient swallows a capsule containing a tiny camera that records and transmits images as it passes through the gastrointestinal tract. Some studies have found it to be much more accurate for evaluating small bowel disease than barium x-rays or CT scans. Patients also find it easier to tolerate than standard endoscopy.
Ultrasound. Intestinal wall ultrasound is proving to be useful for identifying the extent and severity of Crohn's disease. Although it is unclear if ultrasound is useful for an initial diagnosis, one study indicated that it is effective for identifying Crohn's disease or ulcerative colitis when used by experienced professionals.
Upper and Lower Gastrointestinal Barium X-Rays. An upper gastrointestinal barium x-ray may be used if Crohn's disease is suspected in the small intestine. Swallowed barium passes into the small intestine and shows up on an x-ray image, which may reveal inflammation, ulcers, and other abnormalities.
Click the icon to see an image of the barium enema procedure.
Computed Tomography (CT) Scans. Computed tomography (CT) scans are proving to be useful in evaluating active IBD. With Crohn's disease, CT scans may show thickened walls and complications, such as fistulas, which occur outside the intestine.
Magnetic Resonance Imaging (MRI). Magnetic resonance imaging is another advanced imaging technique that may be useful for detecting abscesses and other injuries related to Crohn's disease in the pelvis. A variant called magnetic resonance spectroscopy (MRS) may prove to be useful for differentiating between Crohn's disease and ulcerative colitis.
Using Tests to Differentiate Between Crohn's Disease and Ulcerative Colitis | |
Endoscopy | Ulcerative colitis almost always involves the lower left colon and rectum and can be diagnosed using sigmoidoscopy. Crohn's disease may require colonoscopy as well. Endoscopy often reveals ulcers, diseased regions that have a cobblestone-like appearance in Crohn's disease, but not in ulcerative colitis. |
X-Rays (Barium Enema) or Computed Tomography Scans | In ulcerative colitis, inflammation is usually evenly distributed on the surface lining of the intestine, and the bowel wall bleeds easily when touched with a swab. The pattern observed in Crohn's disease is usually one of scattered patches of ulcers that are deep, thick, and large. Crohn's disease produces pockets (fissures) or channels (fistulas). They do not occur with UC. In ulcerative colitis the ileum (the lower part of the small intestine) is often dilated while it is narrowed in Crohn's disease. |
Laboratory Tests | Tissue samples obtained from a patient with Crohn's disease may reveal granulomas, small collections of inflammatory cells. Granulomas may also be present in other conditions, however. Tissue samples should also be examined for the presence of cancerous cells. In tests for antibodies, about 70% of tests for patients with UC will show immune factors called perinuclear-staining antineutrophil cytoplasmic antibodies, and over 50% of Crohn's patients have anti-Saccharomyces cerevisiae antibodies. Each of these antibody groups shows up only occasionally in the other disorder. |
Ruling Out Diseases Resembling Inflammatory Bowel Disease
Irritable Bowel Syndrome. Irritable bowel syndrome (IBS), also known as spastic colon, functional bowel disease, and spastic colitis, causes many of the same symptoms as inflammatory bowel disease. (However, it is NOT the same as inflammatory bowel disease.) Bloating, diarrhea, constipation, and abdominal cramps are all symptoms of IBS. Irritable bowel syndrome is not caused by inflammation, however, and no fever or bleeding occurs. Behavioral therapy may be helpful in treating IBS. (No psychologic therapy improves inflammatory bowel disease.)
Microscopic Colitis. Microscopic colitis causes chronic watery diarrhea, but the colon lining shows little or no signs of inflammation. It may be genetically linked to celiac sprue. Most patients can expect to improve.
Celiac Sprue. Celiac sprue, or celiac disease, is an intolerance to gluten (found in wheat) that triggers inflammation in the small intestine and causes diarrhea, vitamin deficiencies, and stool abnormalities. It occurs in a significant number of people with IBD and is usually first noticed in children.
Click the icon to see foods to avoid if you have celiac sprue.
Interstitial Cystitis. Interstitial cystitis (IC) is an inflammation of the bladder wall that occurs almost exclusively in women. Some evidence suggests that the risk for IBD in these patients is 100 times above that in the general population and that there may be some common factor to both conditions. The average age of patients with IC is 40, but 25% of cases occur in women under 30. Symptoms are very similar to urinary tract infections, but no bacteria are present. Pain during sex is a very common complaint in these patients, and stress may intensify symptoms.
Infections. If endoscopy reveals inflammation, a doctor must always rule out possible infections before a diagnosis of inflammatory bowel disease can be confirmed.
Acute Appendicitis. Crohn's disease may cause tenderness in the right lower part of the abdomen where the appendix is located and resemble appendicitis.
Click the icon to see an image of the appendix.
Cancer. Colon or rectal cancers must always be ruled out when symptoms of IBD occur.
Intestinal Ischemia. Symptoms similar to IBD can be caused by blockage of blood flow in the intestine. This is more likely to occur in elderly people.
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