What is the appropriate assessment and management approach for vomiting in a child?

Approach to Vomiting in Children

Immediate Priority: Identify Life-Threatening Causes

Bilious vomiting at any age is a surgical emergency requiring immediate evaluation for intestinal obstruction, particularly midgut volvulus, which can cause complete intestinal necrosis within hours. 1, 2

Critical Red Flags Requiring Urgent Action

• Bilious (green) vomiting indicates obstruction distal to the ampulla of Vater and mandates stopping oral intake, placing a nasogastric tube for gastric decompression, obtaining immediate surgical consultation, and proceeding to upper GI contrast study 1, 2
• Bloody vomitus or "currant jelly" stools suggest intussusception or serious mucosal damage requiring urgent imaging 1, 2
• Toxic appearance with fever may indicate sepsis, meningitis, bacterial sepsis, pneumonia, or urinary tract infection—all requiring immediate recognition and treatment 3, 4
• Altered mental status or severe lethargy suggests increased intracranial pressure, metabolic disorder, or severe systemic illness 2, 4
• Severe dehydration (≥10% fluid deficit) with prolonged skin tenting >2 seconds, cool extremities, decreased capillary refill, and lethargy requires immediate IV rehydration 3, 1

Age-Specific Diagnostic Approach

Newborns (First 2 Days of Life)

• Obtain abdominal radiograph as initial imaging for vomiting with poor feeding or no meconium passage 3
• "Double bubble" sign indicates duodenal atresia; "triple bubble" with absent distal gas indicates jejunoileal atresia 3, 1
• Fluoroscopy contrast enema is indicated for distal bowel obstruction pattern 3
• Upper GI series is indicated for bilious vomiting with nonclassic findings or few distended loops 3

Infants 2 Weeks to 3 Months

• Ultrasound abdomen is the initial imaging for nonbilious projectile vomiting to diagnose hypertrophic pyloric stenosis (HPS), which typically presents between 3-6 weeks of age 3, 1
• Upper GI series is mandatory for any bilious vomiting to evaluate for malrotation with volvulus, regardless of normal plain radiograph, as X-rays have up to 7% false-negative rate 3, 2

Infants and Toddlers (3 Months to 2 Years)

• Watery diarrhea with vomiting in a child <2 years most likely represents viral gastroenteritis and does not require antimicrobial therapy or imaging if the child appears well 3, 1
• Intussusception presents with crampy abdominal pain, "currant jelly" stools, and progression to bilious vomiting; ultrasound is the recommended initial imaging 1, 2
• Do not assume viral gastroenteritis without excluding serious bacterial infections (meningitis, sepsis, UTI, pneumonia) in febrile infants 4

Clinical Assessment Framework

History Must Include

• Vomitus characteristics: bilious (green), bloody, projectile, or nonbilious 1, 2
• Stool pattern: bloody, "currant jelly," watery diarrhea, or absent 3, 1
• Fluid intake and urine output: significant dehydration unlikely if no decrease reported 5
• Associated symptoms: fever, abdominal pain, altered mental status, toxic appearance 3, 4
• Recent exposures: antibiotic use (C. difficile), daycare (Giardia, Shigella), foreign travel 3

Physical Examination Priorities

• Vital signs including blood pressure to assess for shock 2
• Hydration status using clinical signs: mild dehydration (3-5% deficit) shows increased thirst and slightly dry mucous membranes; moderate (6-9% deficit) shows loss of skin turgor and dry mucous membranes; severe (≥10% deficit) shows lethargy, prolonged skin tenting >2 seconds, cool extremities, and decreased capillary refill 3, 1
• Abdominal examination for distension, tenderness, masses, and adequate bowel sounds before initiating oral therapy 3, 2
• Hernial orifices and genitalia to exclude incarcerated hernia 6
• Fundoscopic examination if altered mental status present 6

Laboratory and Imaging Decisions

• No routine laboratory or imaging for well-appearing children with clear viral gastroenteritis pattern 7, 5
• Obtain serum electrolytes, blood gases, renal and liver functions in any child with dehydration or red flag signs 7
• Low serum bicarbonate combined with clinical parameters predicts dehydration 8
• Stool cultures indicated for bloody diarrhea, white blood cells on methylene blue stain, recent antibiotic use, daycare exposure, recent foreign travel, or immunodeficiency 3

Treatment Algorithm

For Viral Gastroenteritis (Most Common Cause)

Oral rehydration therapy is the cornerstone of treatment, with early refeeding using age-appropriate diet once rehydrated. 3, 1

• Mild dehydration: manage at home with half-strength apple juice followed by preferred liquids or oral rehydration solutions 5
• Moderate dehydration: use oral rehydration solutions; ondansetron (0.2 mg/kg oral, maximum 4 mg) may be given if persistent vomiting impedes oral intake 7, 8, 5
• Severe dehydration: hospitalization with IV fluid resuscitation is required 1, 5
• Early refeeding with age-appropriate diet once rehydrated; do not delay nutrition 3

Medications: What to Use and Avoid

• Ondansetron (0.2 mg/kg oral; 0.15 mg/kg parenteral; maximum 4 mg) decreases vomiting, improves oral intake success, reduces need for IV hydration, and shortens ED stay with minimal side effects 7, 8, 5
• Antimicrobials are NOT indicated for watery diarrhea and vomiting in children <2 years, as this represents viral gastroenteritis 3, 1
• Antidiarrheal agents (loperamide, kaolin-pectin) are contraindicated: they do not reduce diarrhea volume or duration, can cause severe abdominal distention and ileus (including deaths reported), and shift focus away from appropriate fluid and electrolyte therapy 3

Common Pitfalls to Avoid

• Never dismiss bilious vomiting as "just gastroenteritis": midgut volvulus accounts for 20% of bilious vomiting cases in the first 72 hours and requires immediate surgical evaluation 1, 2
• Do not rely on abdominal X-ray alone for suspected malrotation: proceed directly to upper GI series if clinical suspicion remains high, as radiographs miss up to 7% of cases 2
• Infants are at higher risk for dehydration due to higher body surface-to-weight ratio, higher metabolic rate, and dependence on others for fluid 3, 4
• Benign gastroesophageal reflux (GER) with normal weight gain does not require imaging, but poor weight gain, blood in vomit/stool, or bilious vomiting elevates concern to GERD or surgical pathology requiring aggressive intervention 1, 2
• Fever, vomiting, and loose stools can indicate non-GI illnesses: meningitis, bacterial sepsis, pneumonia, otitis media, urinary tract infection, metabolic disorders, congestive heart failure, toxic ingestions, or trauma must be excluded with detailed history and physical examination 3, 4