﻿ Clostridium Difficile Colitis (Antibiotic-Associated Colitis, C. difficile colitis) Symptoms, Causes, Treatment - How is Clostridium difficile colitis diagnosed? - MedicineNet

Clostridium Difficile Colitis (cont.)

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How is Clostridium difficile colitis diagnosed?


A history of antibiotic use is important in the diagnosis of C. difficile colitis. Patients taking antibiotics (or recently having taken antibiotics) who develop abdominal pain, cramps and diarrhea are usually tested for C. difficile infection. However, doctors do not always wait for the appearance of diarrhea to start testing for C. difficile since in rare instances C. difficile can cause abdominal pain and tenderness without diarrhea.

Laboratory tests

Patients with C. difficile colitis often have elevated white blood cell counts in the blood, and, in severe colitis, the white blood cell counts can be very high (20,000 to 40,000). Patients with C. difficile colitis also often have white blood cells in their stool when a sample of stool is examined under a microscope. Elevated white blood cell counts and white blood cells in the stool, however, only demonstrate that there is colitis and not that the cause of the colitis is C. difficile. More specific tests are necessary to determine whether C. difficile is the cause of the colitis.

The most widely used test for diagnosing C. difficile colitis is a test that detects toxins produced by C. difficile in a sample of stool. There are two different toxins, toxin A and toxin B, both capable of causing colitis. Accurate tests for both toxins are available commercially for use in all laboratories. Unfortunately, like most tests in medicine, these tests for toxins are not perfect; both false positive tests (finding toxins when there is no C. difficile) and false negative tests (not finding toxins when C. difficile is present) can occur. Therefore, other tests such as flexible sigmoidoscopy and colonoscopy often are necessary to look for pseudomembranes that are characteristic of C. difficile colitis.

Flexible sigmoidoscopy and colonoscopy

Flexible sigmoidoscopy is an examination in which a doctor inserts a flexible fiberoptic tube with a light and a camera on its end into the rectum and sigmoid colon. (The sigmoid colon is the segment of the colon that is closest to the rectum.) In most patients with C. difficile colitis, the doctor will find pseudomembranes in the rectum and the sigmoid colon. However, some patients with C. difficile colitis will have pseudomembranes only in the right colon (the segment of the colon farthest from the rectum). Patients with pseudomembranes confined to the right colon require colonoscopy in order to see the pseudomembranes. (A colonoscope is a longer version of the flexible sigmoidoscope that is long enough to reach the right colon.)


X-ray examinations and computerized tomography (CT) examinations of the abdomen will occasionally demonstrate thickening of the wall of the colon due to inflammation, but these X-ray findings also are non-specific and only demonstrate that colitis is present. They do not demonstrate the cause of the colitis, for example, C. difficile.

Medically Reviewed by a Doctor on 5/13/2015

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