What are the differential diagnoses and initial management for nausea and vomiting in a child?

Differential Diagnosis for Nausea and Vomiting in Children

Immediate Life-Threatening Conditions to Exclude First

Any bilious (green) vomiting constitutes a surgical emergency until proven otherwise and mandates immediate imaging and surgical consultation. 1

Critical Red Flags Requiring Emergency Evaluation

• Bilious vomiting indicates obstruction distal to the ampulla of Vater; in neonates within 72 hours of life, 20% represent midgut volvulus, which can cause intestinal necrosis within hours 1, 2
• Abdominal distension with decreased/absent bowel sounds suggests intestinal obstruction or necrotizing enterocolitis (NEC) 3
• Blood in stool or vomit signals mucosal injury and raises suspicion for NEC or intussusception 3
• Fever, hypothermia, lethargy, poor perfusion, increased oxygen requirements indicate late-onset sepsis 3
• Temperature instability, lethargy, altered mental status may indicate sepsis or inborn error of metabolism 3

Age-Specific Differential Diagnoses

Neonates and Young Infants (<3 months)

Gastroesophageal reflux disease (GERD) is the most frequent cause of recurrent non-bilious vomiting in infants, especially preterm infants with immature lower esophageal sphincter function. 4, 3

• GERD: Non-forceful regurgitation with maintained weight gain; occurs daily in 50% of healthy infants 4, 3
• Hypertrophic pyloric stenosis (HPS): Non-bilious projectile vomiting in infants 2-12 weeks old; palpable epigastric "olive" mass in 60-80% of cases; metabolic alkalosis on labs 3, 2
• Intestinal atresia (duodenal, jejunal, ileal): Bilious vomiting in first days of life 1
• Malrotation with midgut volvulus: Can present with intermittent non-bilious vomiting that progresses to bilious emesis; surgical emergency 3, 1
• Hirschsprung disease: Bilious vomiting with failure to pass meconium 1
• Necrotizing enterocolitis: Abdominal distension, feeding intolerance, bloody stools, temperature instability 3
• Sepsis/meningitis: Fever or hypothermia, lethargy, poor perfusion 3, 1

Older Infants (3-12 months)

• Acute viral gastroenteritis: Most common cause of acute vomiting; viral pathogens (especially rotavirus and norovirus) identified in 51.7% of children with isolated vomiting 5, 6
• Intussusception: Intermittent crampy abdominal pain (inconsolable crying, drawing up legs), "currant jelly" stools, progression from non-bilious to bilious vomiting 2
• Bacterial gastroenteritis: Vomiting most associated with Vibrio cholerae (90.9%) and Shigella (64.6%); fever common with Yersinia, Salmonella 7
• Food allergy: Chronic regurgitation and GERD may be presenting symptom 5

Children >1 Year

• Viral gastroenteritis: Norovirus detected in 29.8% of children with vomiting 6
• Bacterial gastroenteritis: Campylobacter, Salmonella, Shigella 4, 8
• Intussusception: Peak incidence 5-9 months but can occur in older children 2
• Increased intracranial pressure: From meningitis, encephalitis, mass lesions 1
• Metabolic disorders: Lethargy, poor feeding, abnormal neurologic exam 3
• Gastroparesis: Chronic nausea, vomiting, postprandial fullness; can occur in diabetic children 4

Initial Diagnostic Approach

History and Physical Examination

Differentiate vomiting from regurgitation, rumination, and bulimia; assess duration, frequency, severity, and associated symptoms. 4

• Vomiting characteristics: Forceful vs. effortless; bilious (green) vs. non-bilious; bloody vs. non-bloody 4, 3
• Hydration status: Capillary refill, urine output ≥4 wet diapers/24 hours, mucous membrane moisture 3
• Weight trajectory: Poor weight gain or weight loss differentiates pathologic GERD from benign reflux 4, 3
• Abdominal examination: Palpate for "olive" mass (HPS), assess for distension, bowel sounds 3, 2
• Stool characteristics: Bloody, watery, frequency 4, 7

Laboratory Evaluation

• Electrolyte panel: Metabolic alkalosis suggests HPS; metabolic acidosis seen in NEC or sepsis 3
• Stool testing: Consider in children with diarrhea; test for Campylobacter, E. coli O157/STEC, Salmonella, Shigella, Vibrio, Yersinia, norovirus, rotavirus 9
• Blood cultures: If sepsis suspected 3

Imaging Studies

For bilious vomiting: Obtain abdominal radiograph immediately, followed by upper GI contrast series if obstruction confirmed. 1, 2

• Plain abdominal radiographs (supine and cross-table lateral): Identify dilated bowel loops, pneumatosis intestinalis (NEC), obstruction patterns, "double bubble" sign 3, 1
• Upper GI contrast series: Definitive study for malrotation (96% sensitivity); identifies abnormal duodenojejunal junction position 1, 2
• Abdominal ultrasound: For suspected HPS (pyloric muscle thickness >3-4 mm, channel length >15-17 mm) or intussusception 3, 2

Initial Management

Acute Gastroenteritis (No Red Flags)

Oral rehydration therapy is the cornerstone of management; administer small, frequent volumes (≈5 mL every minute) if dehydration present. 4, 3

• Ondansetron may be given to children >4 years with acute gastroenteritis and vomiting to facilitate oral rehydration (reduces immediate need for hospitalization/IV rehydration) 4
• Antimotility drugs (loperamide) should NOT be given to children <18 years with acute diarrhea (deaths reported in 0.54% of children, all <3 years old) 4
• Early refeeding with full-strength formula or breast milk; lactose-free diet reduces diarrhea duration by 18 hours 4
• Antibiotics rarely indicated: Only for Shigella (azithromycin), severe Campylobacter (azithromycin), Vibrio cholerae, or severe Salmonella (ceftriaxone or ciprofloxacin) 8

Benign GERD (No Red Flags)

A 2-4 week trial of smaller, more frequent feeds combined with upright positioning after feeds is recommended for infants with benign-appearing examinations. 3

• Continue full-strength formula or breast milk; dilution not advised 3
• Reassess weight gain and symptom progression 4, 3

Surgical Emergencies

Place infant nil per os (NPO) and initiate nasogastric/orogastric decompression when NEC, obstruction, or any surgical pathology suspected. 3

• Immediate surgical consultation for bilious vomiting, suspected malrotation/volvulus, intussusception, or NEC 3, 1, 2

Common Pitfalls

• Normal abdominal radiographs do not exclude malrotation or volvulus; clinical suspicion based on bilious vomiting alone mandates upper GI study 1
• Viral gastroenteritis should only be diagnosed after careful consideration of other causes, particularly surgical emergencies 5
• Antiemetics are generally contraindicated in preterm infants because they may mask clinical deterioration 3
• Do not delay imaging based on normal initial radiographs in children with bilious vomiting 1