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How is colitis diagnosed?
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
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
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).
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
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.
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