When are lab testing and diagnostic imaging necessary for diagnosis of irritable bowel syndrome (IBS)?

Updated: Dec 11, 2019
  • Author: Jenifer K Lehrer, MD; Chief Editor: BS Anand, MD  more...
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A comprehensive history, physical examination, and tailored laboratory and radiographic studies can establish a diagnosis of irritable bowel syndrome in most patients. The specificity of the Rome III criteria may be improved by including information about nocturnal stools, somatization, and affective disorders on the basis of the clinical history as well as including hemoglobin and C-reactive protein levels with other diagnostic studies. [30]  Routine serologic or genetic testing is not indicated in patients with irritable bowel syndrome (IBS) in all US populations as it appears that celiac disease is uncommon in IBS in this country. [31]

The 2009 American College of Gastroenterologists (ACG) evidence-based position statement on the management of IBS does not recommend laboratory testing or diagnostic imaging in patients younger than 50 years with typical IBS symptoms and without “alarm features”. Alarm features include the following symptoms and history [3] :

  • Weight loss

  • Iron deficiency anemia

  • Family history of certain organic GI illnesses (eg, inflammatory bowel disease, celiac sprue, colorectal cancer)

Although rectal bleeding and nocturnal symptoms have also been considered alarm features, they are not specific for organic disease. Patients with IBS-D or IBS-M should have serologic testing for celiac sprue. Patients aged 50 years and older should have more extensive testing, including a colonoscopy. [3]

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