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  1. What questions in the diarrhea history will guide the need for diagnostic testing?

  2. What is the yield of commonly ordered diagnostic stool tests?

  3. What is a practical algorithm to guide rational diagnostic stool testing?

  4. What are practical supportive therapies for hospitalized patients with diarrhea?

  5. What are the key preventative measures for preventing the spread of infectious diarrhea?

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Case 80-1

A previously healthy 45-year-old man sustained a motor vehicle accident resulting in multiple bony fractures and a traumatic brain injury. As such, he was admitted to the intensive care unit, intubated, sedated, and later taken to the operating room for repair of multiple fractures. On hospital day 3, the surgical team requested a medicine consultation for assessment and management of diarrhea. The patient had no history of diarrhea prior to admission, and his symptoms began on hospital day 2. The diarrhea was loose, semi-formed, 4–6 times a day, without blood, mucus, or pus. The patient remained intubated and sedated. His vital signs were stable, he was afebrile, and his abdominal exam was benign. He received feedings via a nasogastric tube, reaching nutritional goals. His medications included subcutaneous heparin prophylaxis, a proton-pump inhibitor, docusate, senna, intravenous propofol, and intravenous morphine. He had normal laboratory tests, including a white cell count of 8,000 per cubic millimeter.


The typical adult eating a western diet excretes 100–200 grams of fecal matter a day, which consists of water, electrolytes, indigestible matter, unabsorbed food, intestinal secretions, epithelial cells, and enteric bacteria. Diarrhea is defined as an abnormal increase in excretion of fecal matter to >200 grams a day. Although no official definition for nosocomial diarrhea exists, if surmised from the definition of acute diarrhea, it is diarrhea of <2 weeks duration that first presents during an inpatient stay.

The epidemiology of acute nosocomial and acute community-acquired diarrhea are quite disparate, and this chapter will focus on the former. The usual bacterial, viral, and protozoal suspects in community-acquired diarrhea are rare culprits in nosocomial diarrhea. They will be mentioned in this chapter, to sufficiently discuss the differential diagnosis of acute diarrhea, but will be appropriately deemphasized as likely causes of diarrhea in hospitalized patients.


Diarrhea is 1 of the most common afflictions in hospitalized patients, occurring in 33%-50% of inpatients. Patients who acquire diarrhea while in the hospital have longer lengths of stay and higher mortality than those who do not. Diarrhea also is associated with more diagnostic testing (stool studies, imaging exams, electrolyte monitoring), and interventions (intravenous fluids, electrolyte supplementation, and medication adjustments). It also creates issues for sanitation and quality of life, especially in patients that are not independent in mobility and self-care.

The differential diagnosis for diarrhea in hospitalized patients is extensive, but is most conveniently dichotomized into infectious and noninfectious etiologies.

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