What are the emergency department (ED) criteria for evaluating and treating gastroenteritis?

Emergency Department Criteria for Gastroenteritis

In the ED, gastroenteritis should be diagnosed based on sudden onset of vomiting and/or diarrhea with assessment focused on dehydration severity using physical examination findings, while excluding surgical emergencies through targeted history and exam rather than routine laboratory or imaging studies. 1, 2, 3

Clinical Diagnostic Criteria

Cardinal Features Supporting Viral Gastroenteritis

• Sudden onset of vomiting that begins abruptly rather than gradually worsening 2
• Diarrhea developing 24-48 hours after vomiting starts, which should be watery and never bloody 1, 2
• Low-grade fever only, with high fever >39°C occurring in only one-third of viral cases 2
• Duration of 12-60 hours for Norovirus or 3-8 days for rotavirus with expected complete resolution 2
• Cluster or epidemic pattern with other family members or contacts having similar symptoms 2
• Nausea and abdominal cramping occurring in 79% and 71% of cases respectively 2

Red Flags Requiring Alternative Diagnosis Consideration

• Bilious vomiting requires immediate imaging to rule out malrotation with volvulus 1, 2
• Bloody diarrhea with fever warrants stool cultures for bacterial pathogens 2
• Localized right lower quadrant pain necessitates evaluation for appendicitis even without classic findings 1
• Prominent epigastric pain is atypical for viral gastroenteritis, which usually causes diffuse cramping 1
• Constipation with no bowel movement combined with pain could indicate early bowel obstruction 1

Assessment of Dehydration Severity

Physical Examination Findings (Most Reliable)

The physical examination is the best method to evaluate hydration status rather than laboratory testing 3, 4. The three most useful predictors of ≥5% dehydration are:

• Abnormal capillary refill time 4
• Abnormal skin turgor 4
• Abnormal respiratory pattern 4

Additional assessment should include skin turgor, mucous membrane moisture, mental status, and vital signs to categorize dehydration as mild, moderate, or severe 2.

Dehydration Classification

• Mild dehydration: No decrease in oral intake or urine output reported by parents, normal physical examination 3
• Moderate dehydration: Clinical signs present but no shock 3
• Severe dehydration: Signs of shock or >10% dehydration 3

Laboratory and Imaging Criteria

When Laboratory Testing is NOT Needed

• Stool microbiological tests are not routinely needed when viral gastroenteritis is the likely diagnosis based on clinical presentation and mild illness 2, 3
• No single laboratory value accurately predicts degree of dehydration and routine testing is not recommended 4
• Mild leukocytosis can occur with viral gastroenteritis and does not necessarily indicate bacterial infection 2

When Laboratory Testing IS Indicated

• Bloody diarrhea or white blood cells on stool examination warrant stool cultures to rule out bacterial pathogens 2
• Low serum bicarbonate combined with certain clinical parameters may help predict dehydration in select cases 4
• Studies are conflicting on whether BUN or BUN/creatinine ratio correlates with dehydration 4

ED Management Criteria

Mild Dehydration (Can Be Managed at Home)

• Oral rehydration therapy is the mainstay of treatment and is as effective as IV rehydration for preventing hospitalization 3, 4
• Half-strength apple juice followed by preferred liquids can be used 3
• Begin oral rehydration immediately without delaying for diagnostic testing 2

Moderate Dehydration

• Oral rehydration solutions are recommended as first-line therapy 3
• Ondansetron may be prescribed to prevent vomiting and improve tolerance of oral rehydration 1, 3, 4
• Children receiving ondansetron are less likely to vomit, have greater oral intake, and are less likely to require IV rehydration 4
• Monitor QTc interval if using ondansetron, particularly with other QT-prolonging medications 1

Severe Dehydration (Requires Hospitalization)

• IV fluids are indicated for severe dehydration, shock, altered mental status, or failure of oral rehydration 1, 3
• Hospitalization is recommended for children who do not respond to oral rehydration therapy plus antiemetic 3

Admission Criteria from ED

Hospitalization is indicated for: 5

• Infants <3 months of age
• Severe dehydration or signs of shock
• Severe malnutrition
• Toxic appearance
• Persistent vomiting despite antiemetic therapy
• Suspected surgical abdomen

Critical Pitfalls to Avoid

• Do not assume viral gastroenteritis without considering bilious vomiting, which requires immediate imaging 2
• Do not prescribe antibiotics for presumed viral gastroenteritis, as they provide no benefit and may cause harm 2
• Do not delay rehydration while pursuing diagnostic testing if viral gastroenteritis is suspected 2
• Do not rely solely on laboratory values to assess dehydration; physical examination is more reliable 3, 4
• The initial episodes can be misdiagnosed as acute viral gastroenteritis when actually representing food protein-induced enterocolitis syndrome (FPIES), especially if presenting with profound lethargy, hypotension, and increased white blood cell counts 6