Diarrhea is a common condition that can stem from many causes. Fortunately, the care of the ED patient with diarrhea is usually straightforward— a targeted history and physical examination, followed by symptomatic remedies. However, the temptation to dismiss a case as “just diarrhea” can be quite dangerous, as serious disease processes can present with diarrhea as the chief complaint. Some patients require more systematic investigation or even hospitalization. Clinical judgment based on the current evidence can help guide a cost-effective work-up of patients with diarrhea that will identify patients with more severe etiologies or at risk for complications.
Given that diarrhea is such a ubiquitous part of the human condition, it's not surprising that the literature on the subject is truly voluminous. Thousands of studies address the epidemiology, etiology, pathophysiology, evaluation, treatment, differential diagnosis, and other features of patients with diarrhea. Thankfully, a number of well-done reviews, meta-analyses, and position statements from expert medical organizations condense the findings, making the job of the practicing emergency physician caring for patients with diarrhea much easier.1-19
In general, the preponderance of evidence tends to support the following practices in patients with diarrhea:
Diarrhea is a change in normal bowel movements characterized by an increase in the water content, volume, or frequency of stools. Fluid secretion into the gut and increased gut motility together produce both the increased stooling frequency and the increased stool liquidity.16,20 The passage of more than 200 grams of stool per day is considered to be diarrhea; two to three bowel movements per day is the upper limit of normal.
An episode of diarrhea lasting 14 days or less is generally defined as "acute diarrhea," while "persistent diarrhea" refers to episodes lasting longer than 14 days. "Chronic" diarrhea is generally defined as diarrhea that lasts more than 30 days.
Evidence-based medicine requires a critical appraisal of the literature based upon study methodology and number of subjects. Not all references are equally robust. The findings of a large, prospective, randomized, and blinded trial should carry more weight than a case report. To help the reader judge the strength of each reference, pertinent information about the study, such as the type of study and the number of patients in the study, will be included in bold type following the reference, where available. In addition, the most informative references cited in the paper, as determined by the authors, will be noted by an asterisk (*) next to the number of the reference.