Pediatric Vomiting with Fever - Age 3 Years

Overview

Differential Diagnosis

Most Common Causes

Serious / Must-Not-Miss Causes

Other Causes to Consider

• Migraine (in young children, may present with vomiting + abdominal pain + low-grade fever without classic headache)
• Hepatitis (fever, nausea, vomiting, jaundice, abdominal pain)
• Pertussis (paroxysmal cough, post-tussive vomiting, mild fever)

Key note from Tintinalli's Emergency Medicine: In young infants and toddlers, fever may be the only sign of UTI - GU symptoms are often absent in pre-verbal or early-verbal children. Always consider UTI in a 3-year-old with fever and vomiting, even without urinary symptoms.

Clinical Assessment

History

• Onset and duration of fever and vomiting
• Character of vomit: bilious (green) = surgical emergency until proven otherwise; blood-tinged = UGI source
• Associated symptoms: diarrhea (watery vs. bloody), abdominal pain, rash, cough, ear pain, dysuria
• Fluid intake and urine output (most sensitive history for ruling out significant dehydration)
• Sick contacts, daycare exposure, recent travel
• Vaccination history (rotavirus vaccine status)

Examination - Dehydration Assessment

No single clinical variable alone is sufficient to determine severity of dehydration. A combination of findings is used - Tintinalli's Emergency Medicine, p. 887.

Investigations

• Urine dipstick/urinalysis + culture - rule out UTI (low threshold in febrile toddler without clear GI source)
• Blood glucose (rule out hypoglycemia)

• Moderate-severe dehydration requiring IV fluids
• Bicarbonate >15 mEq/L makes significant dehydration unlikely
• Electrolyte abnormalities found in ~50% of children needing IV rehydration; management changed in 10%

• 10 stools/24 hours

• Blood or mucus in stool
• Systemic involvement / fever
• Travel history to endemic areas
• Suspected E. coli O157:H7 (order separately - not on routine culture panel)

• Abdominal X-ray/ultrasound only if surgical cause (intussusception, appendicitis) is suspected
• Tintinalli's: Radiologic investigations play a very limited role in routine pediatric AGE

Management

1. Oral Rehydration Therapy (ORT) - First Line

• Mild dehydration (3-5%): 30-50 mL/kg over 2-4 hours
• Moderate dehydration (6-9%): 60-80 mL/kg over 2-4 hours
• Replace ongoing losses: 10 mL/kg per stool, 2 mL/kg per emesis

• Start with 5 mL (under 2 yrs) or 10 mL (over 2 yrs) every 5 minutes using syringe/spoon
• Increase slowly as tolerated
• Vomiting is NOT a contraindication to ORT - small volumes are usually tolerated

• WHO reduced-osmolarity ORS (Na 75 mmol/L, osmolarity 245 mOsm/L)
• Pedialyte, Enfalyte (commercial options - Na 45-60 mmol/L)
• In mild dehydration/minimal AGE: dilute apple juice followed by preferred fluids is an acceptable alternative with evidence showing fewer treatment failures vs. ORS - [Roberts and Hedges' Clinical Procedures](Roberts and Hedges'), p. 456
• Avoid: juice (undiluted), tea, sports drinks, carbonated beverages (excessive sugar, low sodium)

2. Antiemetic Therapy

• Mechanism: 5-HT3 receptor antagonist
• Dose: 0.15 mg/kg OR simplified weight-based:
  • 2 mg for children 8-15 kg
  • 4 mg for children 15-30 kg
  • Available as syrup or oral dissolving tablets (ODT)
• Start ORT 15-30 minutes after ondansetron
• NNT = 5 to decrease ED vomiting; NNT = 5 to decrease need for IV hydration
• Safe from 6 months of age; minor QT prolongation (~10-17 ms) but unlikely to cause torsades in healthy children
• FDA boxed warning against promethazine in children <2 years; strongly not recommended in older children either
• Other antiemetics (metoclopramide, domperidone) not recommended by AAP for children <5 years

3. When to Use IV Fluids

• Severe dehydration or hemodynamic compromise
• Altered mental status / inability to take oral fluids
• Persistent intractable vomiting despite ondansetron + ORT
• Bilious vomiting (surgical concern)
• Suspected surgical abdomen
• Significant electrolyte abnormality

4. Diet and Nutrition

• Do NOT restrict diet - early refeeding is recommended
• Continue breastfeeding if applicable
• Age-appropriate regular diet as tolerated after rehydration
• Avoid fatty/high-sugar foods initially

5. Antibiotics

• Not indicated for routine viral gastroenteritis
• Indicated for confirmed bacterial causes: Salmonella (if invasive/bacteremic), Shigella (azithromycin), Campylobacter (azithromycin), Giardia (metronidazole)
• If UTI confirmed: oral antibiotics based on local sensitivity (amoxicillin-clavulanate, cefalexin, trimethoprim-sulfamethoxazole)

Red Flags - Admit/Refer Immediately

• Bilious or bloody vomiting
• Signs of severe dehydration or shock
• Altered consciousness / extreme lethargy
• Suspected surgical cause (intussusception, appendicitis)
• Failure of ORT
• Signs of meningism (neck stiffness, bulging fontanelle)
• High/prolonged fever without identified source
• Immunocompromised child or underlying chronic illness
• Electrolyte abnormalities on labs

Disposition Summary

• Tintinalli's Emergency Medicine: A Comprehensive Study Guide, Ch. 131-132, pp. 887-888
• Rosen's Emergency Medicine: Concepts and Clinical Practice, Ch. 167, pp. 3541-3580
• [Roberts and Hedges' Clinical Procedures in Emergency Medicine, p. 456](Roberts and Hedges')
• Red Book 2021: Report of the Committee on Infectious Diseases (AAP)

Recent Evidence Note: A 2025 meta-analysis (PMID: 40739406) found probiotics reduce duration and severity of acute gastroenteritis in children - though this is an adjunct, not a primary treatment.