EM@3AM – Diarrhea

Author: Erica Simon, DO, MHA (@E_M_Simon, EMS Fellow, SAUSHEC, USAF) // Edited by: Alex Koyfman, MD (@EMHighAK, EM Attending Physician, UTSW / Parkland Memorial Hospital) and Brit Long, MD (@long_brit, EM Attending Physician, SAUSHEC, USAF)

Welcome to EM@3AM, an emdocs series designed to foster your working knowledge by providing an expedited review of clinical basics. We’ll keep it short, while you keep that EM brain sharp.

A 36-year-old male presents to the emergency department for six days of profuse, watery diarrhea (> 10 episodes daily) associated with abdominal cramping and nausea. The man reports the onset of his symptoms following his return from a business trip to the Dominican Republic. He denies fevers, bloody stools, recent antibiotic therapy, and ill contacts. He is able to tolerate oral intake, but states that home treatment with loperamide (one day duration) provided no relief.

Triage VS: BP 121/78, HR 110, T 99.1 Oral, RR 14, SpO2 99% on room air.

Pertinent physical examination findings:
HEENT: Topographic tongue
CV: Tachycardia, regular rhythm. Capillary refill 2 seconds.
Abdomen: Soft, non-tender, non-distended; absent guarding and rebound.

What’s the next step in your evaluation and treatment?

Answer: Diarrhea1-4

  • Definition: A change in normal bowel movements with the passage of ≥ 3 stools daily or ≥ 200 g of stool:2
    • Acute diarrhea: duration ≤ 14 days
    • Persistent diarrhea: duration 15-29 days
    • Chronic diarrhea: lasting ≥ 30 days
  • Epidemiology: According to the World Health Organization, more than 1.7 billion cases of diarrhea occur annually worldwide.1 Diarrhea remains a significant cause of child mortality in the developing world (responsible for > 760,000 deaths annually).1 In the U.S., acute diarrheal illnesses result in over 900,000 hospitalizations each year; the majority occurring in patients > age 65.2
  • Clinical Presentation and Etiologies: (Lists offered as examples, not all encompassing):1-3
    • Clinical Presentation: Variable according etiology: Patients frequently report abdominal pain and cramping associated with profuse stools +/- fever. Individuals may present with signs and symptoms ranging from mild volume depletion to hypovolemic shock.
      • Detailed below: * = Invasive diarrheal illness: Associated with fever and bloody stools (red blood cells and/or fecal leukocytes on laboratory examination).
    • Etiologies:
      • Infectious: 3
        • Viral (70% of U.S. cases): Noroviruses (most common), norwalk virus, coronavirus, rotavirus, pararotavirus, picornavirus, HIV enteropathy, enteric adenovirus, *cytomegalovirus, etc.
        • Bacterial (24% of U.S. cases):
          • * = Aeromonas species, Campylobacter species, Enterohemorrhagic Escherichia coli (O157:H7), Mycobacterium species, Salmonella species, Shigella species, Vibrio parahaemolyticus, Vibrio vulnificus, Yersinia entercolitica, Clostridium dificile.
          • Enterotoxigenic Escherichia coli, Vibrio cholerae, Bacillus cereus, Clostridium botulinum, Staphylococcus aureus, etc.
        • Parasitic (6% of U.S. cases):
          • Cryptosporidium, Cyclospora, Giardia lamblia, Isospora belli, Ascaris lumbricoides, Diphyllobothrium latum, Enterobius vermicularis, Taenia species, Trichnella spiralis, Strongyloides stercoralis, etc.
      •  Non-Infectious:
        • Medications: ACE inhibitors, antidepressants, chemotherapy agents, colchicine, digitalis, non-steroidal anti-inflammatories, thyroid hormone, valproic acid, procainamide, etc.
        • Foods: Mannitol, sorbitol, xylitol, fish-associated toxins (ciguatera, scombroid, etc.), and plant-associated toxins (organophosphates, Amanita species muschrooms, Pokeweed, rhubarb), etc.
        • Toxins: Heavy metals, cholinergic agents, etc.
  •  Evaluation:
    • Assess ABCs and obtain vital signs.
    • Perform a thorough history. Question the individual specifically regarding:
      • Duration of symptoms, stool frequency and consistency, the presence of blood in the stool, ability to tolerate oral intake, recent travel, medications, recent antibiotic use or hospitalizations, sick contacts, occupation (Clostridium dificile).
        • Acute diarrhea: Commonly infectious and self-limited => likely viral or bacterial pathogen.
        • Persistent diarrhea => associated with enteric bacterial or protozoal pathogens.
        • Chronic diarrhea => frequently non-infectious.
    •  Perform a focused physical examination. Evaluate for signs of hypovolemia and hypoperfusion:
      • Dry mucosa, cool extremities, diaphoresis, decreased skin turgor, decreased urine output, mental status changes.
      • If bloody diarrhea: evaluate for signs of anemia, i.e. – pale conjunctive, pallor, and delayed capillary refill.
    •  Utilize the H&P to direct laboratory/imaging evaluation:
      • CBC, CMP (electrolytes, renal function), lactate, coags (gastrointestinal bleed), fecal microscopy (leukocytes, fat), fecal ova and parasites, stool culture, C. difficile stool antigen, E. coli O157:H7 toxin assay, Giardia antigen assay, etc.
      • Abdominal plain film (peritoneal signs, concern for perforation) vs. CT of the abdomen with IV contrast vs. US (biliary pathology) as applicable.
  •  Treatment:1,4
    • Resuscitation as appropriate (oral or IV fluids, electrolyte repletion, etc.)
    • Uncomplicated, acute diarrhea => Viral and non-invasive bacterial gastroenteritis are frequently self-limited.
      • Consider an anti-motility agent in the non-toxic appearing adult patient (avoid in elderly patients, pediatric patients, and in individuals reporting recent antibiotic use/hospitalization=> may predispose to toxic megacolon or hemolytic-uremic syndrome (HUS)).
    • Empiric therapy for suspected invasive diarrhea:
      • Ciprofloxacin (500 mg orally twice daily) or levofloxacin (500 mg orally once daily) for 3-5 days (avoid in pregnant patients).4
      • C. difficile treatment: Metronidazole (500 mg orally three times daily) for 10-14 days or oral vancomycin (125 mg four times daily) for 10-14 days.4
    • Pediatric patients => antibiotic treatment has been associated with the development of HUS and thrombotic thrombocytopenic purpura:
      • If possible, antibiotic therapy should be tailored to stool culture results.
  • Disposition:1
    • Uncomplicated, acute diarrhea => home with supportive care and follow-up.
    • Patients with persistent dehydration or hemodynamic instability following initial resuscitation => admit for continued monitoring and care.
  • Pearls:1
    • The differential diagnosis for a patient presenting with a diarrheal illness is broad:
      • Consider: mesenteric ischemia, appendicitis, bowel obstruction, diverticular disease, fecal impaction, fecal incontinence, gastrointestinal cancers, gastrointestinal bleed, inflammatory bowel disease, volvulus, toxic megacolon, hyperthyroidism, pancreatic insufficiency, lactose intolerance, etc.



  1. Lazarciuc N. Diarrhea. In Rosen’s Emergency Medicine: Concepts and Clinical Practice. 9th ed. Philadelphia, Elsevier. 2018; 28:249-256.e2.
  2. Dupont H. Acute infectious diarrhea in immunocompetent adults. N Engl J Med. 2014; 370:1532-1540.
  3. Sabol V, and Carlson K. Diarrhea: applying research to bedside practice. AACN Adv Crit Care 2007; 18:32-34.
  4. Gilbert D, et al. The Sanford guide to antimicrobial therapy. Sperryville, VA: Antimicrobial Therapy, 2014.


 For Additional Reading:

Gastroenteritis Mimics: What should the emergency physician consider?

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