What is the initial management for a patient presenting with gastroenteritis?

Initial Management of Gastroenteritis

The cornerstone of initial management for gastroenteritis is prompt oral rehydration therapy (ORT) using low-osmolarity oral rehydration solution (ORS), with early resumption of normal diet once rehydration is achieved. 1

Immediate Assessment and Rehydration

Assess Hydration Status

Evaluate the patient clinically for signs of dehydration by examining:

• Skin turgor and capillary refill 2
• Mental status and mucous membrane moisture 2
• Vital signs (heart rate, blood pressure) 2
• Categorize dehydration severity: mild (3-5%), moderate (6-9%), or severe (≥10%) 2

Initiate Oral Rehydration Therapy

For mild to moderate dehydration, begin ORT immediately as first-line treatment 3, 1:

Children:

• Administer 50-100 mL/kg of ORS over 3-4 hours 1, 4
• For a 20 kg child, this equals approximately 1000-2000 mL total 4
• If vomiting is present, give small frequent volumes (5-10 mL) every 1-2 minutes, gradually increasing as tolerated 1, 4

Adults:

• Use similar weight-based principles as children 1
• WHO-recommended ORS can be prepared with 3.5 g NaCl, 2.5 g NaHCO3, 1.5 g KCl, and 20 g glucose per liter of clean water 3
• Maintenance of good hydration is particularly important in elderly patients and those on diuretics 3

Alternative Routes if Oral Fails

• Consider nasogastric administration of ORS at 15 mL/kg/hour for patients who cannot tolerate oral intake but have normal mental status 1, 4
• Reserve intravenous rehydration only for severe dehydration, shock, altered mental status, or failure of oral rehydration 2, 5

Dietary Management

Resume normal, age-appropriate diet during or immediately after rehydration is complete 1, 2:

• Continue breastfeeding throughout the illness in infants 1, 2
• Early refeeding is superior to fasting or restrictive diets 1, 2
• Avoid foods high in simple sugars (soft drinks, undiluted apple juice) as they worsen diarrhea through osmotic effects 2

Diagnostic Testing Considerations

Stool testing is NOT needed for mild symptoms resolving within one week 6. However, obtain stool studies if:

• Bloody diarrhea is present 1, 6
• Fever, tenesmus, or signs of inflammatory diarrhea occur 3
• Symptoms persist beyond one week 6
• Recent antibiotic exposure (test for Clostridioides difficile) 6
• Recent foreign travel or immunocompromised status 2

When testing is indicated, fecal lactoferrin or leukocyte testing can identify inflammatory causes that warrant bacterial culture 3.

Pharmacological Considerations

Antiemetics

Ondansetron may be given to children >4 years and adults to facilitate oral rehydration when vomiting is significant 2, 7. This can decrease hospitalization rates and improve ORT compliance 7.

Antimotility Agents

Loperamide is CONTRAINDICATED in children under 18 years with acute diarrhea 1, 2, 8:

• May be used in immunocompetent adults with watery diarrhea once adequately hydrated 1, 2
• Adult dosing: 4 mg initially, then 2 mg after each unformed stool (maximum 16 mg/day) 8
• Avoid in inflammatory diarrhea, bloody stools, fever, or suspected toxic megacolon 1, 2

Antimicrobials

Antibiotics are NOT routinely indicated since viruses cause approximately 70% of gastroenteritis cases 2, 7. Consider antimicrobials only for:

• C. difficile infection 6
• Bloody diarrhea with suspected bacterial pathogen 1
• Severe symptoms with confirmed bacterial etiology 6
• Travel-related diarrhea 6

Adjunctive Therapies

• Probiotics may reduce symptom severity and duration 1, 2
• Zinc supplementation reduces diarrhea duration in malnourished children 6 months to 5 years in areas with high zinc deficiency 2

Infection Control

Implement strict hygiene measures to prevent transmission 2:

• Hand hygiene after toilet use, diaper changes, before food preparation and eating 2
• Use gloves and gowns when caring for affected patients 2
• Clean and disinfect contaminated surfaces promptly (note: many germicides are ineffective against rotavirus, but detergents work) 3
• Isolate ill persons until at least 2 days after symptom resolution 2

Critical Pitfalls to Avoid

• Do not delay rehydration while awaiting diagnostic tests—begin ORT immediately 2
• Do not use sports drinks, apple juice, or soft drinks as primary rehydration fluids for moderate to severe dehydration 4, 2
• Do not give antimotility drugs to children or patients with bloody diarrhea 1, 2
• Do not unnecessarily restrict diet during or after rehydration 1, 2
• Do not assume IV therapy is faster than ORT—studies show IV hydration for gastroenteritis averages 5.4 hours in the ED, exceeding the 4-hour ORT recommendation 5

When to Escalate Care

Hospitalize and provide intensive management for patients with 3, 2:

• Severe dehydration or shock
• Inability to tolerate oral fluids despite antiemetics
• Altered mental status
• Sepsis, neutropenia, or significant bleeding
• Worsening clinical status despite appropriate outpatient management