What is the management for an infant with projectile vomiting after feeding?

Management of Infantile Hypertrophic Pyloric Stenosis

Immediate Diagnostic Priority

This 3-year-old (likely 3-week-old) neonate with progressively forceful vomiting after feeding and intermittent epigastric swelling requires urgent pyloric ultrasound to diagnose hypertrophic pyloric stenosis (HPS), which is the most common surgical cause of non-bilious projectile vomiting in infants. 1, 2

Clinical Recognition

• Classic presentation: Non-bilious projectile vomiting beginning within the first 2-8 weeks of life, with progressively increasing force over several days 1, 3
• Pathognomonic physical finding: Palpable "olive" mass in the right upper quadrant, though this is absent in 11-51% of confirmed cases 2
• Intermittent epigastric swelling: Represents visible gastric peristaltic waves attempting to overcome the pyloric obstruction 2, 4
• Timing pattern: Vomiting occurs immediately after feeding as the stomach cannot empty through the hypertrophied pylorus 3, 4

Diagnostic Approach

Ultrasound is the imaging modality of choice and should be performed immediately 5, 1, 2:

• Diagnostic ultrasound criteria for HPS:

  • Pyloric muscle thickness >3 mm 3
  • Pyloric channel length >15-18 mm 3
  • Target sign appearance 3
  • Lack of gastric emptying during observation 3

• Critical caveat: If initial ultrasound is negative but symptoms persist, repeat ultrasound in 48 hours, as HPS can evolve and early imaging may be falsely negative 3

• Upper GI series is reserved only for equivocal ultrasound results, not as first-line imaging 5

Pre-Operative Management

Stabilization must precede surgery 4:

1. Fluid resuscitation: Correct dehydration and electrolyte abnormalities (typically hypochloremic, hypokalemic metabolic alkalosis) with intravenous normal saline and potassium supplementation 4

2. NPO status: Stop all oral feeds immediately 6

3. Nasogastric decompression: Insert NG tube to decompress the stomach and prevent aspiration 6

4. Surgery is NOT emergent: HPS is an urgent but not emergent condition—adequate resuscitation takes priority over rushing to the operating room 4

Definitive Treatment

Pyloromyotomy is the definitive treatment 4:

• Surgical consultation should be obtained once diagnosis is confirmed 1, 7
• Surgery should proceed only after complete correction of dehydration and electrolyte abnormalities 4
• The procedure involves longitudinal incision of the hypertrophied pyloric muscle 4

Critical Differential Diagnoses to Exclude

While HPS is most likely, bilious vomiting would indicate a surgical emergency requiring different management 8, 1, 7:

• Malrotation with volvulus: Can present at any age and requires immediate surgical evaluation if vomiting becomes bilious 1, 7
• Intussusception: Presents with crampy pain, "currant jelly" stools, and progression to bilious vomiting 7
• The absence of bilious vomiting and presence of regular bowel movements with gas passage argues strongly against mechanical obstruction 1

Common Pitfalls

• Do not delay ultrasound waiting for the "olive" to become palpable—many confirmed cases never have a palpable mass 2
• Do not rush to surgery before correcting metabolic derangements—this increases perioperative complications 4
• Do not dismiss persistent symptoms if initial ultrasound is negative—repeat imaging in 48 hours if clinical suspicion remains high 3
• Do not confuse with gastroesophageal reflux disease (GERD)—GERD causes regurgitation, not forceful projectile vomiting with progressive worsening 1

Post-Operative Feeding

• Feeding can typically resume within 6-24 hours post-operatively 4
• Small, frequent feeds are advanced as tolerated 4
• Some post-operative vomiting is expected but should progressively improve 4