The first step most doctors take in diagnosing ulcerative colitis is to get a medical history, including a detailed inventory of symptoms. The frequency and severity of diarrhea is a good indicator of the seriousness of a patient's ulcerative colitis. Six or more bowel movements per day usually indicate severe disease. The frequency of bowel movements during an attack, compared with the number on a typical day, is more meaningful than the absolute number. Likewise, the number of nocturnal bowel movements is a crucial part of the history of the disease. These symptoms accompanied by fever, low blood pressure, or a rapid heart beat are indicators of severe UC and dictate the need for more extensive testing in a hospital setting.
A key to evaluating ulcerative colitis is ruling out other illnesses that mimic the symptoms of UC. These include a variety of food-borne infections such as campylobacter, shigella, salmonella, E. coli 0157:H7, and amebiasis and other disorders caused by intestinal parasites.
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The risk of colon cancer is elevated by ulcerative colitis. Among patients with pancolitis, UC involving the entire colon, the risk of colon cancer goes up if the disease has been active for eight years or more. In people with UC on the left or distal side of the colon, the risk of colon cancer is higher if they have had the disease for 10 to 15 years or longer. Individuals with UC in these groups should consult their doctors and plan periodic colonoscopies with biopsies to screen for cancer. In general, after a patient has had pancolitis or left-sided UC for more than eight to 10 years, cancer screening with colonoscopy is recommended every one to two years.
Blood tests for hemoglobin in the blood, the white cell count, and the levels of albumin and potassium in the blood are helpful in determining the extent of the disease and the right course of treatment. Stool studies are used to rule out parasites and infectious microbes that also cause bloody diarrhea, abdominal pain, fever, and other symptoms similar to colitis.
Abdominal X-rays: Simple X-rays can show the outlines of the transverse colon in acutely ill patients. They may also reveal the shortening of the colon or tissue changes in the colon.
Barium enema: The barium enema may be helpful in the evaluation of patients with ulcerative colitis but is not always necessary. It shows the ulcer depth, and any fistulas-abnormal ducts or passages leading from the hollow portion of the colon to the surface or to other organs.
During this test, barium, a white, chalky liquid, is administered through a rectal tube. The colon fills up and is visualized with an X-ray or fluoroscope. Air is introduced into the colon until it is fully distended and coated with barium. Spot films are taken during the filling of the colon and a series of overhead films are taken after the patient has been positioned to demonstrate the entire colon. Post-evaluation films are also taken.
Computed tomography (CT): CT scanning is a valuable tool to rule out other conditions that may mimic the symptoms of UC and to look for any possible complications in patients known to have ulcerative colitis. The CT can image the wall of the colon and show how far the disease extends. During the test, contrast liquid is administered orally and/or intravenously. The stomach, small intestine, and colon can all be visualized.
Magnetic resonance imaging (MRI): The application of MRI is limited in ulcerative colitis. It's useful in evaluating the thickness of the colon wall. In UC, inflammation of the tissue in the colon lining leads to scarring and a breakdown of tissue architecture. As a result, the colon walls can narrow and thicken. The more severe the disease, the thicker the colon wall, a condition that increases the risk of obstruction.
Endoscopy is a key diagnostic tool used at the time of initial presentation to confirm the presence of ulcerative colitis and to determine its extent and severity. During endoscopy, the doctor uses a flexible lighted tube with a camera inside that projects images from inside the colon to a video monitor, allowing him or her to view any ulcers, bleeding, or lesions. Air may be infused into the colon to enhance visibility. Patients may experience slight cramping or pressure from the air, but the discomfort resolves as soon as the test is over. During the test, a variety of instruments can be used through the biopsy channel in the endoscope to obtain tissue samples or to remove polyps. Endoscopic tests may also be used when there are subsequent attacks of UC to determine the extent of recurrence and to watch for signs of abnormal changes in cells or possible colon cancer.
There are two main types of endoscopic tests used to diagnosis the presence and severity of ulcerative colitis.
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Colonoscopy is a procedure that usually takes 30 to 60 minutes and can be done in an office or a hospital. It allows the physician to see inside the entire colon and take biopsies, to look for ulceration, bleeding, or abnormal cells or polyps, which can lead to cancer. In addition to being a diagnostic tool for evaluating the severity of ulcerative colitis, it is the key screening method for detecting colon cancer in healthy individuals as well as those with ulcerative colitis.
Sedation is administered so the patient does not experience major discomfort. The colon must be completely empty to do the exam. Generally, patients are placed on a liquid diet for a day or two and given oral laxatives or enemas to clear the colon. During the exam, the physician inserts a long, flexible lighted colonoscope into the rectum and guides it through the entire colon.
Flexible sigmoidoscopy is a simple office procedure that takes only 10 to 20 minutes. The doctor inserts the sigmoidoscope through the rectum into only the lower portion of the large intestine, the sigmoid colon. The exam shows only the lower one third of the colon, so it is the appropriate test for patients with limited ulcerative proctitis or to take a quick look inside to confirm the diagnosis of UC in someone having an acute attack.
Last reviewed on 6/4/09
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