Infantile hypertrophic pyloric stenosis is a thickening of the pylorus muscle that blocks the stomach outlet, usually appearing at 2 to 8 weeks of age. It is more common in firstborn boys and after early exposure to erythromycin.
Key symptoms
- Forceful, projectile, non-bilious vomiting after feeds
- Hungry and wanting to feed again right after vomiting
- Poor weight gain or weight loss
- Fewer wet diapers and constipation
What you find on exam
- Firm, olive-sized mass in the upper belly, best felt after vomiting
- Visible stomach waves moving left to right after a feed
- Signs of dehydration: sunken fontanelle, dry mouth, slow capillary refill
- Weight plotted on the growth chart
Tests
- Abdominal ultrasound: pyloric muscle 3 mm or more thick and 15 mm or more long
- Electrolytes: low chloride, low potassium, metabolic alkalosis
- Blood gas and glucose
- Kidney function
Treatment basics
- IV fluids and correction of electrolytes before surgery
- Stop feeds; nasogastric tube if needed
- Pyloromyotomy once the alkalosis is corrected
- Feeds restart within hours after surgery
Red flags
- Green (bilious) vomiting, which points to malrotation instead
- Lethargy or severe dehydration
- Apnea or a very high bicarbonate
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Sources: NCCPA PANCE Content Blueprint; NBOME COMLEX-USA clinical presentations; AAMC Core Entrustable Professional Activities (Core EPAs). Written by Making Synapses. Making Synapses is not affiliated with these organizations.