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Key Clinical Questions

  • image What questions in the diarrhea history will guide the need for diagnostic testing?

  • image What is the yield of commonly ordered diagnostic stool tests?

  • image What is a practical algorithm to guide rational diagnostic stool testing?

  • image What are practical supportive therapies for hospitalized patients with diarrhea?

  • image What are the key measures for preventing the spread of infectious diarrhea?

CASE 82-1

A previously healthy 45-year-old man sustained a motor vehicle accident resulting in multiple bone 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, semiformed, four to six 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 8000 per cubic millimeter.

Based on the algorithm outlined in Figure 82-1, the patient’s diarrhea started in the hospital, had been present for 1 day, was occurring four to six times a day, and was brown and semiformed. His medication list included docusate, senna, and a proton-pump inhibitor, all of which can lead to diarrhea. He had recently received perioperative antibiotics for the prevention of surgical site infections, but was on no current antibiotic therapy and he was without any other infectious red flags. He had also recently been initiated on enteral feedings and had received oral contrast 2 days ago for abdominal imaging. The proton-pump inhibitor, colace, and senna were stopped, and the rate of his enteral feeds was reduced. His diarrhea resolved within 48 hours and no further diagnostic testing was performed.


The typical adult eating a Western diet excretes 100 to 200 g of fecal matter a day, consisting 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 g a day. Nosocomial diarrhea is an acute diarrheal episode not present during admission and occurring after >3 days of hospitalization.

The epidemiology of acute nosocomial and acute community-acquired diarrhea are quite disparate; this chapter will focus on the former. The usual bacterial, viral, and protozoal culprits in community-acquired diarrhea are rare in nosocomial diarrhea. They will be mentioned in this chapter as patients may acquire them prior to hospital admission, but they will be appropriately deemphasized as causes of diarrhea in ...

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