AGA releases guideline on the evaluation of chronic diarrhea

September 23, 2019

Bethesda, MD (Sept. 23, 2019)-- Diagnosing patients with chronic watery diarrhea can be difficult for health care providers, since several causes with specific therapies, such as inflammatory bowel disease (IBD), microscopic colitis and chronic infection, need to be ruled out. A new clinical guideline1 (superscript 1) from the American Gastroenterological Association (AGA) published in Gastroenterology, the official journal of the AGA Institute, provides recommendations on the appropriate laboratory tests based on current evidence to exclude other diagnoses in the setting of suspected functional diarrhea or irritable bowel syndrome with diarrhea (IBS-D).

"When managing patients with chronic watery diarrhea, it is important for health care providers to determine whether it is being caused by organic disease or a functional disorder, such as functional diarrhea or irritable bowel syndrome with diarrhea," said Walter Smalley, MD, MPH, first author, Veterans Affairs Tennessee Valley Healthcare System and Vanderbilt University School of Medicine, Nashville, Tennessee. "Both functional diarrhea and IBS-D are clinical diagnoses with no defining laboratory tests. A workup to exclude all organic disease is impractical, expensive and potentially dangerous to patients if false-positive tests result in further invasive testing. The AGA guideline on evaluation of chronic diarrhea is intended to reduce practice variation and promote high-quality and high-value care for this patient population."

The AGA guideline applies to patients with properly working immune systems who have "watery" diarrhea of at least four weeks duration. It excludes patients with bloody diarrhea; diarrhea with signs of poor fat absorption; features of alarm symptoms, such as weight loss, anemia and hypoalbuminemia; a family history of IBD, colon cancer or celiac disease; and those with a travel history to regions where diarrhea-related diseases are common.

The guideline recommends considering the use of the following laboratory tests for the evaluation of functional diarrhea and IBS-D in adults:Read the AGA Clinical Practice Guidelines on the Laboratory Evaluation of Functional Diarrhea and Diarrhea-Predominant Irritable Bowel Syndrome in Adults (IBS-D) to review the complete recommendations.

What is diarrhea and IBS-D?

Diarrhea happens when a patient has loose, watery stools three or more times a day. When diarrhea lasts four weeks or more, it is considered chronic, or long-term, diarrhea. While diarrhea is a common health problem, impacting 179 million people in the US a year, it can also be associated with a health condition called irritable bowel syndrome (IBS), a common disorder of the large intestine.

There are different types of IBS -- IBS-D: IBS with diarrhea; IBS-C: IBS with constipation; IBS-M: IBS mixed. General symptoms for all types can include belly pain, cramping in the stomach area, gas, bloating and changes in the stool, such as diarrhea, constipation or an urgent need to go. IBS impacts about 35 million Americans, physically, emotionally and socially.

Resources for health care providersReferences

1 Smalley, W., Falck-Ytter, C., Carrasco-Labra, A., Wani, S., Lytvyn, L., Falck-Ytter, Y. AGA Clinical Practice Guidelines on the Laboratory Evaluation of Functional Diarrhea and Diarrhea-Predominant Irritable Bowel Syndrome in Adults (IBS-D) (2019). DOI:

2 Carrasco-Labra, A., Lytvyn, L., Falck-Ytter, Y., Surawicz, C.M., Chey, W.D. AGA Technical Review on the Evaluation of Functional Diarrhea and Diarrhea-Predominant Irritable Bowel Syndrome in Adults (IBS-D) (2019). DOI:
Media contact: Lucia Allen,, 301-272-1608

About the AGA Institute

The American Gastroenterological Association is the trusted voice of the GI community. Founded in 1897, the AGA has grown to include more than 16,000 members from around the globe who are involved in all aspects of the science, practice and advancement of gastroenterology. The AGA Institute administers the practice, research and educational programs of the organization.

About Gastroenterology

Gastroenterology, the official journal of the AGA Institute, is the most prominent scientific journal in the specialty and is in the top 1 percent of indexed medical journals internationally. The journal publishes clinical and basic science studies of all aspects of the digestive system, including the liver and pancreas, as well as nutrition. The journal is abstracted and indexed in Biological Abstracts, Current Awareness in Biological Sciences, Chemical Abstracts, Current Contents, Excerpta Medica, Index Medicus, Nutrition Abstracts and Science Citation Index. For more information, visit

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