Ulcerative Colitis Diagnosis

The process of diagnosing ulcerative colitis usually begins with a discussion of symptoms with the primary care physician. Other conditions can have symptoms similar to ulcerative colitis. A differential diagnosisthe ruling out of other diseasesoccurs by conducting as many tests as are necessary to confirm a diagnosis of ulcerative colitis.

Flexible Sigmoidoscopy

A procedure called flexible sigmoidoscopy is used to determine the cause of symptoms. Through a scope inserted into the patient’s rectum, the rectum and sigmoid colon are examined visually to determine the extent of the colitis, and whether or not cancer or an ulcer is present.

In ulcerative colitis, early stages reveal bleeding pinpoint lesions within the colon. The flexible sigmoidoscopy also shows whether the patient has larger areas of ulceration within the colon. In the latter stages of ulcerative colitis, the colonic mucosa (lining) becomes affected, and the musculature is compromised. Sigmoidoscopies reveal abnormalities even if the disease is in remission.

The Colon Biopsy

If a questionable ulcer is visualized by the flexible sigmoidoscopy, a biopsy to rule out possible cancerous lesions may be recommended. Another purpose of a biopsy is to distinguish ulcerative colitis from Crohn’s disease, an inflammatory bowel disease that is treated much differently. Biopsies do not always give definitive diagnostic answers, however.

Ruling out Bacterial Colitis

Another procedure used in diagnosing ulcerative colitis is the stool culture. Organisms such as Salmonella, Shigella and Campylobacter can be identified by the cultures if they are present in the stool. These organisms are responsible for bacterial colitis.

People who have been on long-term antibiotics for the treatment of infection should be tested for the bacterium Clostridium difficile. This organism is one of the most common causes of bacterial colitis in the US, affecting millions each year. The prolonged use of antibiotics kills “good” intestinal bacteria allowing C. difficile to take hold. C. difficile can cause abdominal pain, fever, diarrhea and colitis, among other symptoms.

Parasites can also cause diarrhea and should be ruled out by fecal examination before a definitive diagnosis of ulcerative colitis is made.

The Differential Diagnosis

Some of the conditions that can cause symptoms similar to those caused by ulcerative colitis include:

  • Crohn’s disease
  • bacterial infection of the colon with Salmonella, Shigella or Campylobacter
  • infection with intestinal parasites
  • opportunistic infection by Clostridium difficile after prolonged antibiotic use.


Baughman, D.C.