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Pyloric stenosis — MCCQE Part 1 MCQ

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ModerateNausea/VomitingPyloric stenosisMCCQE Part 1

A 3-week-old term neonate has progressively forceful non-bilious vomiting after every feed. Hungry, feeds vigorously after vomiting. Weight loss. Palpable olive-shaped mass in RUQ. Which lab finding is most characteristic?

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Correct answer: A — Hypochloraemic, hypokalaemic metabolic alkalosis

Pyloric stenosis (2-6 weeks): loss of gastric HCl causes hypochloraemic hypokalaemic metabolic alkalosis. US: pyloric muscle >=3mm thick, >=15mm long. Correct electrolytes BEFORE Ramstedt pyloromyotomy.

Reference: CPS / Paediatric Surgery