Infection with G lamblia has been shown to lead to an increased prevalence of IBS as well as chronic fatigue syndrome. In a historic cohort study of patients with G lamblia infection as detected by stool cysts, the prevalence of IBS was 46.1% as long as 3 years after exposure, compared with 14% in controls.

For more on the etiology of IBS, read here.

Postprandial urgency is common, as is alternation between constipation and diarrhea. Symptoms not consistent with IBS should alert the clinician to the possibility of an organic pathology. Inconsistent symptoms include the following:

• Onset in middle or older age

• Acute symptoms (IBS is defined by chronicity)

• Progressive symptoms

• Nocturnal symptoms

• Anorexia or weight loss

• Fever

• Rectal bleeding

• Painless diarrhea

• Steatorrhea

• Gluten intolerance

For more on the presentation of IBS, read here.

A consensus panel created and then updated the Rome criteria to provide a standardized diagnosis for research and clinical practice. The Rome III criteria for the diagnosis of IBS require that patients have had recurrent abdominal pain or discomfort at least 3 days per month during the previous 3 months that is associated with two or more of the following:

• Relieved by defecation

• Onset associated with a change in stool frequency

• Onset associated with a change in stool form or appearance

Supporting symptoms include the following:

• Altered stool frequency

• Altered stool form

• Altered stool passage (straining and/or urgency)

• Mucorrhea

• Abdominal bloating or subjective distention

For more on the criteria for diagnosis of IBS, read here.

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:

• 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.

For more about the workup of IBS, read here.

The selection of pharmacologic treatment remains symptom directed. Agents used for management of symptoms in IBS include anticholinergics, antidiarrheals, tricyclic antidepressants, prokinetics, bulk-forming laxatives, serotonin receptor antagonists, chloride channel activators, and guanylate cyclase C (GC-C) agonists.

A Cochrane systematic review found that several antispasmodics, including peppermint oil, pinaverium, trimebutine, and cimetropium/dicyclomine, significantly outperformed placebo in improving IBS symptom and global assessment scores.

The American College of Gastroenterology's Task Force on the Management of Functional Bowel Disorders noted that the antidiarrheal agent loperamide effectively reduced stool frequency and improved stool consistency, but it did not relieve pain, bloating, or other global IBS symptoms.

For more on the treatment of IBS, read here.

Related Resources Irritable Bowel Syndrome Pediatric Irritable Bowel Syndrome

 

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Cite this article: Jenifer K. Lehrer. Quiz: How Much Do You Know About Irritable Bowel Syndrome? Medscape. Apr 27, 2015.