Tests
1st tests to order
clinical exam
Test
Viral gastroenteritis is usually a clinical diagnosis and no investigations are needed.[9]
Result
symptoms and signs consistent with viral gastroenteritis
Tests to consider
serum electrolytes, BUN, creatinine
CBC
Test
Rarely required. Ordered if an alternative cause of infection or sepsis is suspected.
Leukocyte and granulocyte counts are not sufficiently informative for the early differential diagnosis of viral and bacterial gastroenteritis.[46]
Result
usually normal; elevated WBC count and granulocytes if sepsis is present
blood cultures
Test
Rarely required. Ordered if an alternative cause of infection or sepsis is suspected.
Result
usually normal; may identify a causative organism
stool microscopy
Test
Rarely required. The test should be considered in children with bloody diarrhea because this is more typical of bacterial gastroenteritis.[9]
Result
usually normal; presence of WBCs suggests infection with an invasive cytotoxin-producing organism such as Salmonella, Shigella, or Yersinia enterocolitica
stool culture
Test
Rarely required. Stool cultures should be considered in children with bloody diarrhea to exclude bacterial causes.[41]
Result
negative
enzyme immunoassay (EIA) for detection of viral antigen
Test
Rarely required. Ordered only for epidemiologic purposes when there is a public health imperative to identify the pathogen and establish its source.
EIAs for antigen detection in stool are highly sensitive and specific and are the diagnostic methods of choice.[47]
Result
may show the offending viral pathogen (rotaviruses, noroviruses, astroviruses, adenoviruses)
stool electron microscopy
Test
Rarely required. Ordered only for epidemiologic purposes when there is a public health imperative to identify the pathogen and establish its source.[Figure caption and citation for the preceding image starts]: Transmission electron micrograph of intact rotavirus particles, double-shelled. Distinctive rim of radiating capsomeresCDC/Dr Erskine Palmer; used with permission [Citation ends].
[Figure caption and citation for the preceding image starts]: This transmission electron micrograph reveals some of the ultrastructural morphology displayed by norovirus virions, or virus particlesCDC/Charles D. Humphrey; used with permission [Citation ends].
Electron microscopy is expensive, and examination of a large number of stool specimens is time consuming.
Result
may show the characteristic viral particle
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