Fast Five Quiz: Do You Know Key Differences Between Irritable Bowel Syndrome and Inflammatory Bowel Disease?

Jamie Shalkow, MD; Daniel Margain, MD


July 12, 2018

Patients with IBS aged 50 years or older should have more extensive testing, including a colonoscopy. In patients with IBD, colonoscopy or sigmoidoscopy reveals that the rectum is almost always involved in UC, but it is frequently spared in CD. The disease can be limited to the rectum (proctitis); to the rectum, sigmoid, and descending colon (left-sided colitis); or to the entire colon (pancolitis). UC does not involve any other segment of the GI tract. Colectomy is curative. Colonoscopy with ileoscopy in the assessment of CD has a sensitivity of 74% and a specificity of 100%, leading to a positive predictive value of 100% as a diagnostic test.

The ESR and C-reactive protein (CRP) levels are often used as serologic markers for inflammation in patients with IBD; however, these findings are not specific. Measuring such inflammatory markers aids in monitoring disease activity and response to treatment. A small but significant number of patients with CD or UC may not have elevated ESR or CRP levels, even in the setting of significant active inflammation.

In patients with suspected IBS, a lactose-free diet for 1 week in conjunction with lactase supplements may be indicated. Improvement incriminates lactose intolerance, although the patient's clinical history and response to a trial may be unreliable. Therefore, some gastroenterologists recommend a formal hydrogen breath test. Fructose intolerance must also be considered. Breath testing may also be used to evaluate for small intestinal bacterial overgrowth, as formal jejunal aspiration is now rarely performed.

Esophagogastroduodenoscopy is used for the evaluation of upper GI tract symptoms in patients with IBD, particularly in patients with CD. In patients with IBS, esophagogastroduodenoscopy with possible biopsy is indicated in patients with persistent dyspepsia, if weight loss or symptoms suggest malabsorption, or if celiac disease is a concern.

For more on the workup of IBS, read here.


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