British Society of Gastroenterology
Recommend a careful detailed history to plan investigations.
Recommend screening blood tests for the exclusion of anemia, celiac disease, etc, as well as stool tests for inflammation.
Recommend making a positive diagnosis of irritable bowel syndrome (IBS) following basic blood and stool screening tests.
Cancer or inflammation
Recommend excluding colorectal cancer by colonoscopy in those with altered bowel habit ± rectal bleeding.
Suggest use of testing for fecal blood loss by fecal immunochemical testing in primary or secondary care, either as an exclusion test or to guide priority of investigations in those with lower gastrointestinal symptoms (chronic diarrhea) but without rectal bleeding.
Fecal calprotectin is recommended to exclude colonic inflammation in those suspected with IBS and under the age of 40.
Secondary clinical assessment
If symptoms persist despite normal first-line investigations and treatment, then referral for further investigations is recommended.
We recommend blood and stool tests to exclude malabsorption and common infections (especially in the immunocompromised or elderly).
In those with functional bowel or IBS-diarrhea, a positive diagnosis of bile acid diarrhea should be made either by 75SeHCAT testing or serum bile acid precursor 7α-hydroxy-4-cholesten-3-one (depending on local availability).
Recommend colonoscopy with biopsies of right and left colon (not rectal) to exclude microscopic colitis.
If lactose maldigestion is suspected, suggest hydrogen breath testing (if available) or withdrawal of dietary lactose/carbohydrates from the diet.
MR enterography is recommended for evaluation of small bowel abnormalities, depending on availability.
Video capsule endoscopy (VCE) is recommended for assessing small bowel abnormalities, depending on local availability.
We do not recommend small bowel barium follow-through or barium enteroclysis for the evaluation of small bowel abnormalities because of its poor sensitivity and specificity.
Recommend enteroscopy only for targeted lesions identified by MR enterography or VCE and not for diagnosis of chronic diarrhea.
Recommend fecal elastase testing when fat malabsorption is suspected. We do not recommend para-aminobenzoic acid (PABA) testing.
MRI (rather than CT) is recommended for assessing structural anomalies of the pancreas in suspected chronic pancreatitis.
If small bowel bacterial overgrowth is suspected, recommend an empirical trial of antibiotics, as there is insufficient evidence to recommend routine hydrogen or methane breath testing.
Surgical and structural disorders
Recommend use of anorectal manometry and endoanal ultrasound only when other local pathology has been excluded and conservative measures exhausted.
Recommend radiologic modalities for the investigation of fistulae—MRI or CT with contrast follow-through.
Diarrhea due to hormone-secreting tumors is rare; hence, we recommend testing only when other causes of diarrhea have been excluded.
Arasaradnam RP, Brown S, Forbes A, et al. Guidelines for the investigation of chronic diarrhoea in adults: British Society of Gastroenterology, 3rd edition. Gut. 2018 Apr 13. https://gut.bmj.com/content/early/2018/04/13/gutjnl-2017-315909
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Any views expressed above are the author's own and do not necessarily reflect the views of WebMD or Medscape.
Cite this: John Anello, Brian Feinberg, John Heinegg, et. al. International Clinical Practice Guidelines: 2018 Midyear Review - Medscape - Jul 10, 2018.