Paediatric imaging: antenatal hydronephrosis and PUJ obstruction: practice question

A Radiology 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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Radiology · Paediatric imaging: antenatal hydronephrosis and PUJ obstruction

Sample item

A newborn with antenatally detected hydronephrosis has an ultrasound showing a dilated renal pelvis and calyces with a non-dilated ureter and a normal bladder. What is the most likely cause?

APelvi-ureteric junction obstructionBPosterior urethral valvesCVesicoureteric junction obstructionDPrune belly syndrome

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

The answer and the reasoning

A. Pelvi-ureteric junction obstruction

A dilated pelvicalyceal system with a normal ureter and bladder localises obstruction to the pelvi-ureteric junction, and a MAG3 diuretic renogram assesses drainage and function. It is the commonest cause of antenatal hydronephrosis.

Option by option

A. Pelvi-ureteric junction obstruction (correct)
Correct. Pelvicalyceal dilatation with a normal ureter points to a PUJ obstruction.
B. Posterior urethral valves
Posterior urethral valves cause bilateral dilatation, a thick bladder and a dilated ureter.
C. Vesicoureteric junction obstruction
A VUJ obstruction would dilate the ureter.
D. Prune belly syndrome
Prune belly syndrome shows a lax abdominal wall and a large bladder.

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.

Questions about this Radiology question

What is the answer to this Radiology question?

The best answer is A, Pelvi-ureteric junction obstruction. A dilated pelvicalyceal system with a normal ureter and bladder localises obstruction to the pelvi-ureteric junction, and a MAG3 diuretic renogram assesses drainage and function.

Why is "Posterior urethral valves" not the answer?

Posterior urethral valves cause bilateral dilatation, a thick bladder and a dilated ureter.

Why is "Vesicoureteric junction obstruction" not the answer?

A VUJ obstruction would dilate the ureter.

Why is "Prune belly syndrome" not the answer?

Prune belly syndrome shows a lax abdominal wall and a large bladder.

What concept does this question test?

It tests Paediatric imaging: antenatal hydronephrosis and PUJ obstruction in Radiology. It is the commonest cause of antenatal hydronephrosis.

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 Paediatric imaging: antenatal hydronephrosis and PUJ obstruction?

Learn signs with the image, and the disease they point to. Then use the flashcards and the other Radiology 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.