Pediatric surgery: pyloric stenosis: practice question

A General Surgery question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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General Surgery · Pediatric surgery: pyloric stenosis

Sample item

A 5-week-old infant has progressively forceful nonbilious vomiting after feeds, remains hungry, and has a palpable epigastric olive. Which acid-base disturbance is most likely?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

D. Hypochloremic hypokalemic metabolic alkalosis

Hypertrophic pyloric stenosis causes loss of gastric hydrochloric acid through persistent vomiting, leading to hypochloremic metabolic alkalosis; potassium depletion often develops. Fluid and electrolyte correction precede surgery.

Option by option

  • A. Respiratory acidosis

    Respiratory acidosis reflects hypoventilation, not vomiting.

  • B. Hyperkalemic metabolic acidosis

    Hyperkalemic acidosis is the opposite of the typical electrolyte trend.

  • C. High-anion-gap metabolic acidosis

    High-anion-gap acidosis is not caused by repetitive gastric acid loss.

  • D. Hypochloremic hypokalemic metabolic alkalosis (correct)

    Correct. Gastric acid loss creates the characteristic alkalosis and chloride depletion.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this General Surgery question

What is the answer to this General Surgery question?

The best answer is D, Hypochloremic hypokalemic metabolic alkalosis. Hypertrophic pyloric stenosis causes loss of gastric hydrochloric acid through persistent vomiting, leading to hypochloremic metabolic alkalosis; potassium depletion often develops.

Why is "Respiratory acidosis" not the answer?

Respiratory acidosis reflects hypoventilation, not vomiting.

Why is "Hyperkalemic metabolic acidosis" not the answer?

Hyperkalemic acidosis is the opposite of the typical electrolyte trend.

Why is "High-anion-gap metabolic acidosis" not the answer?

High-anion-gap acidosis is not caused by repetitive gastric acid loss.

What concept does this question test?

It tests Pediatric surgery: pyloric stenosis in General Surgery. Fluid and electrolyte correction precede surgery.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Pediatric surgery: pyloric stenosis?

Learn classic signs and eponyms alongside what they diagnose. Then use the flashcards and the other General Surgery questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.