Crohn's Disease Tests
By Mary-Ann Williams |
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Determining whether a patient has Crohn’s disease or not involves a series of tests that lead down a specific path. Initially, the physician will order the least invasive tests to decide whether to go forward into the more invasive – and costly – tests needed to identify Crohn’s disease.
Blood Tests
A complete blood count (CBC) will be done to identify any problems in order to determine the body’s condition as a whole. The CBC consists of taking a blood sample, usually through the arm at the bend in the elbow. The test is done to determine two different things:
- Red blood cell count (RBC) – to look for anemia, or low RBC.
- White blood cell count (WBC) – to look for an infection or inflammation
A blood test is usually ordered after the initial physical exam. It’s the first step toward understanding what’s going on in the body, and the results are used to help decide where to go next.
Fecal Occult Blood Test
Fecal occult blood test may be one of the earliest tests done. During this test, fecal matter is either gathered at home and brought in for analysis, or collected during an endoscopic exam.
The intent is to look for blood, signs of bacterial infection, malabsorption, parasites, or the presence of white blood cells. The presence of any of these will indicate that the symptoms are not a result of Irritable Bowel Syndrome, though it does not definitively diagnose Crohn’s.
Radioscopic Exams
These tests involve the use of radioactive substances to get a clearer picture of what’s happening inside the body. Any of the following tests may be done in any order – or none maybe ordered – depending on the doctor and where the discomfort appears to be.
- Barium enema – A white, radioactive liquid, barium, is inserted into the colon through the rectum. The barium allows the doctor to see the colon clearly on an x-ray, where he or she will be looking for inflammation, fistulas, or strictures (narrowing of the colon).
- Upper GI scan – Like the barium enema, an upper GI scan (UGI) uses barium to track the flow of the intestinal tract, except that in this case, the barium is swallowed. It allows the physician to see the upper part of the gastrointestinal tract from the mouth to the middle portion of the small intestines using continuous x-rays taken while the barium moves through the system.
- Computerized Axial Topography (CAT) scan – An intense x-ray machine that looks at organs of the body through numerous snapshots of the body, a CAT scan (sometimes called just a CT scan) can give a much more complete look at the bowels. Sometimes an iodine solution is injected through an IV or swallowed to give a better contrast to the x-rays.
- Magnetic resonance imaging (MRI) – This test uses a magnetic field and pulses of radio wave energy to scan the organs inside the body. Like a CAT scan, a solution may be used for a contrast image. If this is the case, an IV will be inserted and the solution will be injected through that.
- Enteroclysis – A small tube is fed through the nose and down through the upper gastrointestinal tract to the small intestines. Barium is then injected through the tube and x-rays are taken.
Endoscopic exams
Endoscopic exams involve the use of a small flexible tube with a camera attached to the end. This tube is inserted through either the mouth or the anus and threaded through the body. The camera allows the physician to actually see the lining of the intestines and determine if there is inflammation, and how much.
In order to get prepared for these tests, most often there is a period of fasting to clear the intestines of waste material. This allows the doctor to get a clearer picture of the lining without having to worry about fighting the waste material. The fasting takes place over the course of four to six days and entails a liquid-only diet during that time. The day before the exam, the doctor may request that a strong laxative be taken, or an enema be done to be sure that there is nothing in the system.
There are three types of endoscopic exams, each looking at a different part of the GI tract:
- Sigmoidoscopy – looks at the rectum and lower colon for signs of Crohn’s disease. This is the most common test for Crohn’s, and is often the first of the endoscopic tests ordered.
- Colonoscopy – examines the entire colon and the lower part of the large intestines. This test may be requested if the sigmoidoscopy doesn’t show anything, or if the concern is believed to be higher up the system after an x-ray.
- Upper endoscopy – scans the upper GI tract by being inserted through the patient’s mouth. Since Crohn’s can exist anywhere in the intestinal tract, this test may be used if determined to be necessary. However, most cases of Crohn’s involve only the lower portion of the bowels, so this is the least used endoscopic exam to diagnose Crohn’s.
During the endoscopic exams, a small portion of the intestines may be taken for further study. This is referred to as a biopsy. The tissue may be able to offer additional information, such as if there is an infection, parasite, or other type of problem that can only be seen under a microscope.
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