Chronic Diarrhea: Diagnosis and Management

Lawrence R. Schiller; Darrell S. Pardi; Joseph H. Sellin


Clin Gastroenterol Hepatol. 2017;15(2):182-193. 

In This Article

How Can Clinicians Distinguish Irritable Bowel Syndrome From Other Causes of Chronic Diarrhea?


4. The Rome criteria provide a framework for the diagnosis of IBS and emphasize pain. Other etiologies should be sought when these criteria are not met. (1a)

5. Patients without alarm features who meet criteria for IBS should be treated without further testing. Those who do not respond should be evaluated further. (2b)

Criteria have been proposed to distinguish IBS from organic diseases; however, the utility of these criteria is only partially understood at present.[3] The Rome criteria emphasize chronic abdominal pain that is relieved by defecation, associated with a change in stool frequency or consistency.[3] IBS with diarrhea is diagnosed in patients who meet these criteria and have loose stools more than 25% of the time and hard stools less than 25% of the time. The specificity of symptom-based criteria for the diagnosis of IBS versus other colonic pathology is only moderate (~75%),[7–9] but the incorporation of alarm features can improve specificity to ~90%.[9] However, the predictive value of symptoms in identifying organic disease is less than 10%.[10] The performance of symptom-based criteria was highly variable and might not be able to reliably distinguish IBS from other diseases.[8] Thus, symptoms may be more useful in identifying patients requiring additional evaluation than in identifying patients with organic illnesses.[11]

Because functional diarrheal problems are so common, the pretest probability of organic disease is low, suggesting that an extensive diagnostic evaluation is not needed in most patients.[8,12]

Diagnostic tests such as radiography, serology, and biochemistries are generally not helpful in patients who meet criteria for IBS.[13,14] One area of uncertainty is testing for celiac disease (CD). One meta-analysis suggested that the prevalence of CD in patients meeting criteria for IBS was more than 4-fold that of controls without IBS,[15] whereas a more recent study showed no increased prevalence of CD in patients presenting with IBS.[16] Likewise, microscopic colitis may be present in 1.5%–10% of patients meeting criteria for IBS[17,18] and even higher in older patients. The yield of tests for small intestinal bacterial overgrowth (SIBO) is quite variable.[19]