Diagnosis of Irritable Bowel Syndrome (IBS)
The diagnosis of IBS is one of exclusion. This means that a firm diagnosis cannot be made until all other causes of your symptoms have been ruled out. This can require a rather extensive evaluation.
Your doctor will begin with questions about your symptoms and medical history, and then perform a physical and rectal exam. Several tests will be done to look for signs of other conditions such as:
Most experts currently make the diagnosis of IBS based on the “Rome Criteria”. These criteria are largely based on the symptoms that you report. According to the Rome III Criteria, IBS can be diagnosed when you have two or more of the following symptoms at least three days a month during the preceding three months:
- Pain relieved by defecation (having a stool)
- Onset of symptoms with a change in stool frequency
- Onset of symptoms with a change in stool appearance
Other symptoms such as straining, mucous, or bloating can be used to further support the diagnosis. Tests are often used to “rule out” conditions that may have similar symptoms but with more serious consequences or different treatments.
Tests may include:
Stool Cultures —This involves examining a stool sample in the laboratory to look for infectious agents.
Blood and Urine Tests —These tests check for signs of more serious intestinal disease.
X-ray of the Bowel
Other Tests —These may include:
- Biopsy of the colon: the removal of a piece of colon tissue for testing
- Absorption tests: to help determine if food is being digested and absorbed or just passing through the intestines without being properly digested or absorbed
- X-rays of the stomach or gall bladder
- Blood tests, such as those to check liver, thyroid, or adrenal function. Blood work can also be used to look for celiac disease (wheat allergy).
- Hydrogen breath testing: to help determine whether “bacterial overgrowth” is present
American Gastroenterological Association website. Available at: http://www.gastro.org/ . Accessed March 3, 2006.
Fauci AS, Braunwald E, Isselbacher KJ, et al. Harrison's Principles of Internal Medicine . 14th ed. New York, NY: The McGraw-Hill Companies; 2000.
Irritable Bowel Syndrome Self-help and Support Group website. Available at: http://www.ibsgroup.org . Accessed March 3, 2006.
Pimentel M, Park S, Mirocha J, et al: The effect of a nonabsorbed oral antibiotic (rifaximin) on the symptoms of the irritable bowel syndrome: a randomized trial. Ann Intern Med . 2006;145(8):557-563
Rome Foundation. Guidelines—Rome III Diagnostic Criteria for Functional Gastrointestinal Disorders. J Gastrointestin Liver Dis. 2006;(3):307-312.
Last reviewed June 2008 by
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
Copyright © 2007 EBSCO Publishing All rights reserved.