Shigellosis Workup

Updated: Aug 20, 2021
  • Author: Heba Rashid Ashraf, MD; Chief Editor: BS Anand, MD  more...
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Approach Considerations

Stool culture should be obtained in all suspected cases of shigellosis. Specimens should be processed immediately after collection. Ova and parasite stool studies should be collected to rule out other causes of infectious diarrhea such as Entamoeba histolytica and parasitic worms.

Other laboratory tests, such as a white blood cell (WBC) count, may be performed in persons with severe symptoms or to rule out other causes. Creatinine and blood urea nitrogen (BUN) should be monitored to assess the hydration status of the patient.

Laboratory studies generally reveal the following findings:

  • Fecal leukocytes and erythrocytes

  • Mildly elevated hematocrit, sodium, and urea nitrogen levels: These are indicative of volume depletion in cases of shigellosis.

  • Leukocytosis: Rare.

  • Positive findings on stool culture of a fresh fecal specimen

  • Immunocompromised patients (eg, infected with human immunodeficiency virus [HIV]): Blood cultures are rarely helpful in cases of shigellosis.




Sigmoidoscopy is not necessary in most cases of shigellosis.

Colonic biopsy

If distinguishing between dysentery and the acute presentation of idiopathic ulcerative colitis is urgently necessary, a colonic biopsy may be useful if it is performed within 4 days of the onset of symptoms.

In general, histologic findings of shigellosis include the following:

  • Intense neutrophilic and mononuclear cells infiltrating the lamina propria

  • Hemorrhage

  • Ulcers

  • Mucous depletion

  • Occasional crypt abscesses