What is the approach for a 7-month-old infant presenting with projectile vomiting post feeds?

Approach for 7-Month-Old with Projectile Vomiting Post Feeds

Projectile vomiting in a 7-month-old infant requires urgent evaluation for hypertrophic pyloric stenosis (HPS) or other mechanical obstructions, as these represent serious conditions requiring prompt surgical intervention. 1

Initial Assessment and Red Flags

• Projectile vomiting is considered a "red flag" symptom that requires thorough evaluation, as it may indicate a serious underlying condition rather than simple gastroesophageal reflux 1
• Distinguish between regurgitation (effortless return of feeds) and projectile vomiting (forceful ejection of stomach contents) 1
• Assess for other concerning symptoms:
  • Bilious vomiting (suggests obstruction distal to the ampulla of Vater) 1
  • Blood in vomit or stool 1
  • Abdominal distension 1
  • Weight loss or poor weight gain 1
  • Lethargy, irritability, or altered mental status 2, 3

Key Differential Diagnoses

Mechanical/Surgical Causes (Priority Evaluation)

• Hypertrophic pyloric stenosis (HPS) - most common surgical cause of non-bilious projectile vomiting, though typically presents earlier (2-8 weeks of age) 1, 4
• Malrotation with or without volvulus (can present at any age) 1
• Extrinsic pyloric obstruction (rare but reported in older infants) 5
• Intussusception (though uncommon before 3 months of age) 1

Non-Surgical Causes

• Gastroesophageal reflux disease (GORD/GERD) 1
• Gastroenteritis 1, 2
• Formula intolerance 1
• Increased intracranial pressure 1, 2
• Metabolic disorders 1

Diagnostic Approach

1. Physical Examination:

   • Assess hydration status carefully 2, 3
   • Palpate for the classic "olive" mass in the right upper quadrant (pathognomonic for HPS) 1, 4
   • Examine for abdominal tenderness, distension, or masses 2, 3
   • Check fontanelle and head circumference to rule out increased intracranial pressure 1

2. Initial Imaging:

   • Ultrasound is the imaging modality of choice for suspected HPS 4, 5
   • Point-of-care ultrasound by trained emergency physicians can diagnose HPS with high accuracy 4
   • Abdominal X-ray if signs of intestinal obstruction are present 1

3. Laboratory Studies (if indicated):

   • Electrolytes to assess for dehydration and metabolic alkalosis (common in HPS) 2, 3
   • Consider additional tests based on clinical suspicion for other causes 2, 3

Management Approach

Immediate Management

• Ensure adequate hydration; IV fluids may be necessary if dehydration is present or oral intake is not tolerated 1, 2
• If bilious vomiting or signs of obstruction are present, place nasogastric tube for decompression 2, 3
• Withhold feeds temporarily if mechanical obstruction is suspected 1, 2

Definitive Management

• Surgical consultation is required if HPS or other mechanical obstruction is confirmed or strongly suspected 1, 4
• For non-obstructive causes:
  • Consider trial of smaller, more frequent feeds 1
  • Feed thickening agents may be helpful for GERD 1
  • Avoid routine use of acid-suppressing medications for simple reflux 1
  • Antiemetics (ondansetron) may be considered in select cases where vomiting impedes oral intake 2, 3

Important Considerations and Pitfalls

• While HPS typically presents between 2-8 weeks of age, atypical presentations in older infants do occur and should not be missed 5
• Do not assume projectile vomiting is simply due to GERD without ruling out mechanical causes 1
• Avoid using upper GI contrast studies as the first-line investigation for suspected GERD 1
• Regular reassessment is crucial if diagnosis is not clear initially, as symptoms may evolve 6
• Parental reassurance and education are important components of management, especially for non-surgical causes 3, 6