What is the differential diagnosis (D/D) of projectile vomiting after food intake?

Differential Diagnosis of Projectile Vomiting After Food Intake

The differential diagnosis of projectile vomiting after food intake varies critically by age, with hypertrophic pyloric stenosis being the most common surgical cause in infants under 6 months, while food protein-induced enterocolitis syndrome (FPIES), gastroparesis, cyclic vomiting syndrome, and mechanical obstruction must be considered based on patient age and clinical context. 1

Age-Specific Differential Diagnosis

Infants (0-12 months)

Neonatal Period (First Week of Life)

• Congenital gastrointestinal abnormalities are the primary consideration when vomiting presents in the first week of life 1
• Malrotation with or without volvulus - can present with bilious or nonbilious vomiting and represents a surgical emergency 1
• Intestinal atresia (antropyloric, small bowel, or colon) 1
• Annular pancreas 1
• Hirschsprung disease causing functional obstruction 1
• Meconium ileus 1

Infants Beyond Neonatal Period (Weeks to Months)

• Hypertrophic pyloric stenosis (HPS) - the most common surgical cause of nonbilious projectile vomiting, typically presenting between 2-8 weeks of age with incidence of 2-5/1000 live births 2, 3

  • Classic presentation: forceful, projectile nonbilious vomiting with palpable "olive" mass 1
  • Gastric emptying shows complete stasis in severe cases, normalizing 8-16 days post-pyloromyotomy 2
  • Rare after 6 months of age - children presenting with projectile vomiting after this age require investigation for alternative causes 3

• Gastric volvulus - rare but important cause that can mimic HPS, particularly mesenteroaxial type associated with diaphragmatic eventration 4

• Food Protein-Induced Enterocolitis Syndrome (FPIES) 1

  • Severe acute FPIES: repetitive projectile vomiting (≥4 episodes) occurring 1-4 hours after food ingestion 1
  • Associated features: lethargy, pallor, dehydration, potential hypotension and shock 1
  • Most common triggers: cow's milk, soy (early onset <9 months), rice, oat (later onset) 1
  • Cumulative incidence: 3 per 1000 newborns for cow's milk-induced FPIES 1
  • Can present as chronic form with daily ingestion causing intermittent vomiting, chronic diarrhea, and failure to thrive 1

• Gastroesophageal reflux (GER) - most common cause of nonbilious vomiting/regurgitation in infants, typically benign and self-resolving 1

  • Infants with normal weight gain and no other symptoms typically do not have obstruction 1

• Phreno-pyloric syndrome - in-series incompetence of pyloric and lower esophageal sphincters causing duodenogastroesophageal reflux with projectile bile-stained vomiting in neonates 5

Children and Adults

Gastroparesis

• Delayed gastric emptying without mechanical obstruction causing postprandial nausea, vomiting, early satiety, and bloating 6
• Common etiologies: diabetic, idiopathic, postsurgical 6
• Diagnosis requires gastric emptying scintigraphy performed for at least 2 hours (4-hour testing preferred for higher diagnostic yield) 6
• Critical pitfall: Hyperglycemia itself can slow gastric emptying, leading to false positive results 6

Cyclic Vomiting Syndrome (CVS)

• Stereotypical episodes of acute-onset vomiting lasting <7 days with at least 3 discrete episodes per year 1
• Approximately 65% experience prodromal symptoms (median 1 hour) before vomiting onset 1
• Episodes often occur in early morning hours 1
• Triggered by stress (70-80% of patients), sleep deprivation, hormonal fluctuations, infections 1
• Strong association with personal or family history of migraines 1

Post-Bariatric Surgery Complications

• Surgical complications: band slippage, esophageal stricture, bowel obstruction, internal hernia, gastric ulcers 7
• Internal hernia presents with acute, persistent crampy/colicky epigastric pain after Roux-en-Y gastric bypass 7
• One-third of postoperative emergency room visits within 3 months relate to dehydration 7

Critical Clinical Clues

Red Flags Requiring Urgent Evaluation

• Bilious emesis suggests obstruction distal to ampulla of Vater - requires immediate evaluation for malrotation/volvulus 1
• Repeated forceful vomiting warrants evaluation for underlying obstruction 1
• Projectile vomiting in infants >6 months requires investigation beyond HPS 3

Timing Patterns

• 1-4 hours post-ingestion: FPIES (can range 30 minutes to 6 hours) 1
• Immediate to 1 hour: mechanical obstruction, HPS 1, 2
• Variable with prodrome: CVS 1

Associated Features

• Diarrhea within 24 hours: FPIES (onset typically 5-10 hours) 1
• Lethargy and pallor: severe FPIES, CVS 1
• Metabolic acidosis, methemoglobinemia: severe FPIES 1
• Abdominal pain: present in most CVS episodes (should not exclude diagnosis) 1

Diagnostic Approach Algorithm

Step 1: Age and Timing Assessment

• Neonate (<1 week): Prioritize congenital GI abnormalities, obtain abdominal radiograph as initial imaging 1
• Infant (weeks to 6 months): Consider HPS, FPIES, malrotation 1, 3
• Infant (>6 months): Investigate beyond HPS for alternative causes 3
• Older children/adults: Consider gastroparesis, CVS, functional disorders 1, 6

Step 2: Character of Vomitus

• Bilious: Upper GI series or contrast enema after initial radiograph to evaluate for malrotation/obstruction 1
• Nonbilious projectile: Ultrasound for HPS in appropriate age group, consider FPIES if food-related pattern 1

Step 3: Pattern Recognition

• Episodic with symptom-free intervals: CVS 1
• Consistently 1-4 hours after specific foods: FPIES 1
• Chronic postprandial: Gastroparesis, functional dyspepsia 6

Step 4: Definitive Testing

• Ultrasound: First-line for suspected HPS (pyloric muscle thickness, channel length) 1
• Gastric emptying scintigraphy: Gold standard for gastroparesis (minimum 2 hours, preferably 4 hours) 6
• Upper endoscopy: Rule out mechanical obstruction before diagnosing functional/motility disorder 6
• Oral food challenge: Diagnostic for FPIES when performed in controlled setting 1

Common Pitfalls to Avoid

• Assuming all infant projectile vomiting is HPS - consider gastric volvulus, extrinsic pyloric compression, and FPIES 3, 4
• Overlooking FPIES in formula-fed infants - chronic form presents with intermittent vomiting and failure to thrive, not just acute projectile episodes 1
• Performing gastric emptying studies <2 hours - inaccurate for gastroparesis diagnosis 6
• Not controlling blood glucose during gastroparesis testing - hyperglycemia causes false positive delayed emptying 6
• Failing to check thiamin levels with vomiting >2-3 weeks - prevents neurological complications 7
• Missing malrotation in older infants/children - can present at any age with decreasing frequency 1