What is acute gastroenteritis in pediatric patients?

Acute Gastroenteritis in Pediatrics

Definition and Clinical Presentation

Acute gastroenteritis in pediatric patients is a diarrheal disease of rapid onset characterized by inflammation of the gastrointestinal mucous membranes, presenting with diarrhea (with or without nausea, vomiting, fever, or abdominal pain), typically caused by viral pathogens in 90% of cases. 1, 2, 3

Core Clinical Features

• Diarrhea is the defining symptom—increased frequency and decreased consistency of stools 1, 3
• Vomiting frequently accompanies diarrhea, particularly in viral gastroenteritis 4, 1
• Fever may be present but is not universal 1, 3
• Abdominal pain occurs variably depending on the pathogen and severity 1

Epidemiologic Context

• Acute gastroenteritis accounts for 1.5 million office visits, 200,000 hospitalizations, and 300 deaths annually in U.S. children 1
• It represents the second most common non-traumatic cause of emergency hospitalization in children aged 1-5 years (9% of cases) 5
• Viral pathogens predominate: 47% rotavirus, 29% norovirus, and 14% adenovirus 5
• Bacterial, protozoal, and helminthic causes occur but are less common, particularly in developed countries 3

Pathophysiology

• Gastroenteritis involves inflammation of the gastrointestinal mucous membranes leading to increased secretion and decreased absorption of fluids and electrolytes 3
• The resulting fluid losses through vomiting and diarrhea create the primary clinical concern: dehydration 3

Assessment of Dehydration Severity

Clinical Evaluation Framework

The physical examination is the best method to evaluate hydration status, with dehydration categorized as mild (3-5% fluid deficit), moderate (6-9% fluid deficit), or severe (≥10% fluid deficit). 6, 1

Most Reliable Clinical Predictors

• Abnormal capillary refill time correlates well with fluid deficit (though affected by fever, ambient temperature, and age) 6, 4
• Prolonged skin turgor with skin retraction time >2 seconds when pinched 6, 4
• Abnormal respiratory pattern (rapid, deep breathing indicating metabolic acidosis) 6, 4
• Acute weight change provides the most accurate assessment when premorbid weight is known 6, 7

Additional Assessment Parameters

• Evaluate mucous membrane moisture, mental status, and vital signs 6, 7
• Significant dehydration is unlikely if parents report no decrease in oral intake or urine output and no vomiting 1
• The four-item Clinical Dehydration Scale can be used to determine severity based on physical examination findings 1

Laboratory Testing

• Laboratory tests are not routinely recommended for assessing dehydration, as no single laboratory value accurately predicts the degree of dehydration 4
• Low serum bicarbonate combined with certain clinical parameters may predict dehydration 4
• Blood urea nitrogen (BUN) or BUN/creatinine ratio shows conflicting correlation with dehydration 4
• Complete blood counts and acute phase reactants are indicated only in patients with signs of severe disease 2

Diagnostic Approach

When to Test for Pathogens

• Stool microbiological tests are not routinely needed when viral gastroenteritis is the likely diagnosis in children with mild illness 1
• Microbiological testing is reserved for prolonged or complicated cases and patients with specific risk factors 2
• Consider testing in: bloody diarrhea, recent antibiotic use, exposure to certain pathogens, recent foreign travel, immunodeficiency, or institutionalized settings 6

Red Flags Requiring Immediate Attention

• Severe dehydration signs: severe lethargy or altered consciousness, prolonged skin tenting (>2 seconds), cool and poorly perfused extremities, decreased capillary refill, rapid deep breathing 6
• Bloody stools with fever and systemic toxicity may indicate bacterial infection (Salmonella, Shigella, enterohemorrhagic E. coli) 6
• Persistent vomiting despite small-volume oral rehydration solution (ORS) administration 6
• Absent bowel sounds on auscultation is an absolute contraindication to oral rehydration 6

Management Principles

Primary Treatment: Oral Rehydration Therapy

Oral rehydration solution (ORS) is the first-line treatment for mild to moderate dehydration in children, successfully rehydrating >90% of children with vomiting and diarrhea without antiemetic medication. 6, 1, 5

• Use low-osmolarity ORS formulations rather than sports drinks or juices 6
• Administer small, frequent volumes (5-10 mL every 1-2 minutes) via spoon or syringe to prevent triggering vomiting 6, 7
• Gradually increase volume as tolerated 6, 7
• For moderate dehydration (6-9% deficit): administer 100 mL/kg ORS over 2-4 hours 6, 7
• Replace ongoing losses: 10 mL/kg ORS for each watery stool and 2 mL/kg for each vomiting episode 6

Alternative Routes When Oral Fails

• Nasogastric administration of ORS is equally effective as intravenous rehydration and is the treatment of first choice for children who cannot tolerate oral intake or refuse to drink adequately 6, 5
• Continuous nasogastric application should be considered before resorting to intravenous therapy 5

Intravenous Rehydration

• Reserve IV rehydration for: severe dehydration (≥10% deficit), shock, altered mental status, failure of oral rehydration therapy, or ileus 6, 7
• Use isotonic fluids (lactated Ringer's or normal saline) 6
• Administer 20 mL/kg over 30 minutes for severe dehydration 7
• Transition to ORS once pulse, perfusion, and mental status normalize 6

Nutritional Management

• Continue breastfeeding throughout the diarrheal episode 6
• Resume age-appropriate diet immediately during or after rehydration 6, 7
• Early refeeding reduces severity and duration of illness 6, 7
• Avoid foods high in simple sugars (soft drinks, undiluted apple juice), high-fat foods, and caffeinated beverages 6

Pharmacological Considerations

Antiemetics

• Ondansetron may be given to children >4 years to facilitate oral rehydration when vomiting is significant 6
• Ondansetron (0.15 mg/kg orally dissolving tablet) decreases vomiting rate, improves oral intake success, reduces need for IV rehydration, and shortens emergency department stay 7, 4
• Very few serious side effects have been reported 4

What NOT to Use

• Loperamide is absolutely contraindicated in children <18 years with acute diarrhea due to serious adverse events including ileus, drowsiness, potentially fatal abdominal distention, and deaths 6, 7
• Antimotility agents, adsorbents, antisecretory drugs, and toxin binders should not be used as they do not reduce diarrhea volume or duration 6
• Metoclopramide should never be used in gastroenteritis management (it accelerates transit, which is counterproductive) 6

Antimicrobial Therapy

• Empirical antibiotherapy should not be initiated except in specific situations: infants <3-6 months with suspected bacterial AGE, patients with underlying disease, signs of sepsis, institutionalized patients, or settings with risk of dissemination 2
• Antimicrobial agents have limited usefulness since viral agents are the predominant cause 6

Adjunctive Therapies

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

Hospitalization Criteria

Admit children with severe dehydration (≥10% fluid deficit), signs of shock, failure of oral rehydration therapy after ondansetron trial, altered mental status, ileus, or intractable vomiting preventing adequate oral intake. 6, 7

• Infants <3 months warrant careful consideration for admission due to higher risk of severe dehydration and complications 6
• Lower thresholds for admission apply to immunocompromised patients 6

Infection Control

• Practice proper hand hygiene after toilet use, diaper changes, before food preparation and eating, and after handling soiled items 6
• Use gloves and gowns when caring for children with diarrhea 6
• Clean and disinfect contaminated surfaces promptly 6
• Separate ill children from well children until at least 2 days after symptom resolution 6

Prevention

• Handwashing, breastfeeding, and rotavirus vaccination reduce the incidence of acute gastroenteritis in young children 1
• Families should keep ORS at home at all times and begin administration when diarrhea first occurs, before seeking medical care 6

Common Pitfalls to Avoid

• Do not delay rehydration therapy while awaiting diagnostic testing 6
• Do not use inappropriate fluids like apple juice or sports drinks as primary rehydration solutions for moderate to severe dehydration 6
• Do not unnecessarily restrict diet during or after rehydration 6
• Do not underestimate dehydration in infants, who are more prone to dehydration due to higher body surface-to-weight ratio and higher metabolic rate 6
• Do not routinely hospitalize children with mild or moderate dehydration for IV rehydration when oral rehydration is appropriate 5