August 28, 2015
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Colitis (cont.)

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How is colitis diagnosed?

Patient history

  • In patients with abdominal pain and diarrhea, it is important to find out when the symptoms began, how long they have lasted, whether they come and go, and what makes them better or worse.
  • Travel history is important, especially if the patient has recently visited an area with potentially contaminated water or poor food hygiene. Patients often ask if the symptoms are caused by food poisoning, but that is a difficult question to answer immediately. Usually this occurs with consumption of poorly handled and stored food in a home or a family gathering event.
  • Blood in the stool, whether it is mixed in with the bowel movement, or just drops in the toilet bowl, is not normal. While it may be due to hemorrhoids, other potential causes that are more worrisome may need to be explored. Questions might be asked about bowel habits, weight loss, weakness, or family history of bowel disorders including cancer or colon polyps. Depending on the health care professional's concerns, information may need to be obtained about other body systems, past medical history, social habits (including smoking, drinking, and occupational hazards or risks).

Physical examination

Once the history is taken, physical examination will be helpful in determining the potential causes of the symptoms.

  • Signs of more severe disease with dehydration may include orthostatic changes in blood pressure and pulse rate, where vital signs are taken both laying down and standing up. In patients who are dehydrated, have had rectal bleeding, or are anemic; blood pressure and pulse may be normal when they lie flat but may change when standing; the blood pressure falls and the pulse rate rises.
  • Temperature often is checked for fever.
  • Examination of the abdomen includes palpitating or feeling for tenderness and masses in the abdomen. Bowel sounds are often listened for with a stethescope.
  • The exam also may include a rectal examination to test the stool for blood and feel for a possible rectal mass.
  • If there is a concern for ischemic bowel as the cause of colitis, the examination may assess the heart and blood vessels, looking for signs of atherosclerosis or narrowing of arteries.
  • In patients where the clinical diagnosis is colitis secondary to a viral infection, no further testing is needed. However, this would not apply to a patient who appears ill, dehydrated, or has significant pain, fever, or blood in the stool.

Other tests

A complete blood count (CBC) measures hemoglobin and hematocrit, looking for anemia. If the red blood cell count is elevated, it may be due to dehydration, where total body water is decreased and the blood becomes concentrated.

The CBC also measures the white blood cell count, which may be elevated as the body responds to infection. However, an elevated white blood cell count does not necessarily equal infection, since elevation may be due to the body's reaction to any stress or inflammation.

Electrolytes may be measured looking for changes in the sodium, potassium, chloride and bicarbonate levels in the blood that help determine the severity of dehydration and loss of fluid.

Kidney function may be checked by measuring the BUN (blood urea nitrogen) and creatinine levels; this may be an important clue as well to the severity of dehydration.

Urinalysis may reveal dehydration if the specific gravity (urine concentration) is elevated or if there are ketones present.

Stool samples may be collected for culture, searching for bacterial and parasitic infections as the cause of colitis. Stool may also be tested for blood.

Imaging and procedures

Colonoscopy: The length of the colon can be directly viewed by colonoscopy. A gastroenterologist uses a thin, flexible tube equipped with a fiberoptic camera to view the inside lining of the colon. The appearance of the colonic lining often allows the doctor to make the diagnosis and also provides the opportunity to look for tumors and polyps. Biopsies - small bits of tissue - can be obtained from the mucosal lining during colonoscopy and evaluated under the microscope to determine the cause of colitis. Biopsy is the only way to diagnose microscopic colitis.

Computerized tomography and barium enema are tests that are performed by a radiologist to explore the potential cause of colitis. CT scan of the abdomen has become a more common test to evaluate patients with abdominal pain. However, it is important for the health care professional to balance the risk of radiation with the reward of the information that can be obtained.

Medically Reviewed by a Doctor on 2/4/2015


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