Urology: post-obstructive diuresis: 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.

Try it

General Surgery · Urology: post-obstructive diuresis

Sample item

A 72-year-old man with chronic urinary retention has 2.5 litres drained after catheterisation. Next morning his urine output is 400 mL per hour, and he is thirsty, with postural hypotension. What is the most appropriate management?

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

The answer and the reasoning

D. Monitor urine output and electrolytes and replace losses with intravenous fluids

After relief of chronic high-pressure retention, some patients develop a post-obstructive diuresis from a retained solute and urea load and temporary tubular concentrating defect. It is usually self-limiting but can cause dehydration, hypokalaemia and hypotension. Management is close monitoring with intravenous replacement of fluid and electrolyte losses, avoiding over-replacement that sustains the diuresis.

Option by option

  • A. Intravenous furosemide

    A diuretic would worsen volume depletion in a patient already diuresing.

  • B. Clamp the catheter to stop the diuresis

    Clamping the catheter would re-obstruct the bladder and risk renal damage.

  • C. Desmopressin

    Desmopressin is for diabetes insipidus and is not appropriate for an osmotic diuresis.

  • D. Monitor urine output and electrolytes and replace losses with intravenous fluids (correct)

    Titrated fluid and electrolyte replacement prevents hypovolaemia while the kidney recovers.

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.

More General Surgery questions

Questions about this General Surgery question

What is the answer to this General Surgery question?

The best answer is D, Monitor urine output and electrolytes and replace losses with intravenous fluids. After relief of chronic high-pressure retention, some patients develop a post-obstructive diuresis from a retained solute and urea load and temporary tubular concentrating defect.

Why is "Intravenous furosemide" not the answer?

A diuretic would worsen volume depletion in a patient already diuresing.

Why is "Clamp the catheter to stop the diuresis" not the answer?

Clamping the catheter would re-obstruct the bladder and risk renal damage.

Why is "Desmopressin" not the answer?

Desmopressin is for diabetes insipidus and is not appropriate for an osmotic diuresis.

What concept does this question test?

It tests Urology: post-obstructive diuresis in General Surgery. It is usually self-limiting but can cause dehydration, hypokalaemia and hypotension. Management is close monitoring with intravenous replacement of fluid and electrolyte losses, avoiding over-replacement that sustains the diuresis.

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 Urology: post-obstructive diuresis?

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.