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Pyloric stenosis — USMLE Step 3 MCQ

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EasyPediatrics (well-child, chronic management)Pyloric stenosisUSMLE Step 3

A 5-week-old boy has progressively worsening nonbilious projectile vomiting after feeds. He remains hungry after vomiting. Examination shows mild dehydration and a palpable olive-shaped epigastric mass. Labs show hypochloremic metabolic alkalosis. Which of the following is the most likely diagnosis?

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Reveal the answer and explanation

Correct answer: B — Hypertrophic pyloric stenosis

Projectile nonbilious vomiting, hunger after feeds, palpable olive, and hypochloremic metabolic alkalosis indicate pyloric stenosis.

Reference: AAP pediatric surgery guidance: https://www.aap.org/