patient history diagnosis of colitis and its causes always begins with the taking of the patient's history. the information the patient provides helps the physician guide the direction for diagnosis and treatment. 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. questions may be asked about travel because infections may arise while traveling particularly in undeveloped countries. patients often ask if the cause of symptoms is food poisoning but that is often a difficult question to answer immediately. if the patient has blood with bowel movements (which in general is not normal) further questions may be explored to screen for colon cancer or polyps. food poisoning not due to bacterial infections usually does not cause blood in the stool. evaluation of the body's other systems (cardiovascular neurological) may be necesseary. physical examination once the history is taken physical examination will be helpful in determining potential causes of the symptoms. signs of more severe disease with dehydration may include orthostatic changes in blood pressure and pulse rate (decreases in the former and increases in the latter upon standing). in patients who are low on fluid or blood blood pressure and pulse may be normal when they lie flat but may change with standing; the blood pressure falls and the pulse rate rises. temperature often is checked for fever. examination of the abdomen will disclose areas of tenderness and potentially abnormal masses if tumors or crohn's disease are present. the exam also may include a rectal examination to test the stool for blood and to feel for abnormal rectal masses. in patients where ischemic colitis is a consideration the health care practitioner may examine the heart and listen for sounds of abnormal restricted blood flow (bruits) in arteries located in the neck groin and abdomen as signs of coexisting vascular disease. in patients where there is clinical suspicion of viral infection no further testing may be needed. however in a patient who appears ill dehydrated or has significant pain fever or blood in the stool more evaluation may be required. other tests blood tests may be useful to explore the possibility of anemia or low red blood cell count due to bleeding. an elevated white blood cell count may be present as the body's response to infection. however an elevated white blood cell count does not necessarily mean infection since the white cell count may be elevated as part of the body's general response to any type of inflammation. blood chemistries may be measured looking for changes in electrolyte concentrations in the body especially abnormal sodium and potassium levels that would suggest serious diarrhea or loss of fluid. kidney function may be checked by measuring the bun (blood urea nitrogen) and creatinine levels; this may be an important clue that patients are dehydrated. as well certain bacterial causes of diarrhea may also cause kidney failure. stool samples will likely be collected for culture searching for bacterial and parasitic infections as the cause of colitis. imaging colonoscopy is a test in which a gastroenterologist uses a thin flexible tube with a fiberoptic camera attached to it to look at the inside of the colon searching for the cause of the symptoms. 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 removed from the mucosal lining during colonoscopy and then evaluated under the microscope to make or confirm a diagnosis of the presence or cause of colitis. computerized tomography and barium enemas are tests that are performed by a radiologist to explore the cause of colitis but often are ordered as part of the evaluation of abdominal pain or diarrhea.
how is colitis diagnosed?