Local and regional anaesthesia: urinary retention after neuraxial block: practice question

A Anaesthesia 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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Anaesthesia · Local and regional anaesthesia: urinary retention after neuraxial block

Sample item

Eight hours after spinal anaesthesia for hernia repair, a young man cannot pass urine despite a full bladder. Blockade of which outflow explains the retention?

ACervical outflow (C3 to C5) to the diaphragmBLumbar plexus (L1 to L3) motor supply to the abdominal wallCThoracolumbar sympathetic outflow (T10 to L2) to the bladder neckDSacral parasympathetic outflow (S2 to S4) controlling detrusor contraction

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

The answer and the reasoning

D. Sacral parasympathetic outflow (S2 to S4) controlling detrusor contraction

The sacral segments are among the last to recover after a neuraxial block. Loss of detrusor contraction and sensation of bladder filling leads to retention, which is more frequent with long-acting agents, intrathecal opioids and anticholinergic drugs. Bladder scanning or catheterisation is needed.

Option by option

A. Cervical outflow (C3 to C5) to the diaphragm
The phrenic roots are unrelated to bladder function.
B. Lumbar plexus (L1 to L3) motor supply to the abdominal wall
The lumbar plexus does not control the detrusor.
C. Thoracolumbar sympathetic outflow (T10 to L2) to the bladder neck
Sympathetic blockade does not prevent micturition.
D. Sacral parasympathetic outflow (S2 to S4) controlling detrusor contraction (correct)
Correct. S2 to S4 parasympathetic block abolishes bladder emptying.

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 Anaesthesia question

What is the answer to this Anaesthesia question?

The best answer is D, Sacral parasympathetic outflow (S2 to S4) controlling detrusor contraction. The sacral segments are among the last to recover after a neuraxial block.

Why is "Cervical outflow (C3 to C5) to the diaphragm" not the answer?

The phrenic roots are unrelated to bladder function.

Why is "Lumbar plexus (L1 to L3) motor supply to the abdominal wall" not the answer?

The lumbar plexus does not control the detrusor.

Why is "Thoracolumbar sympathetic outflow (T10 to L2) to the bladder neck" not the answer?

Sympathetic blockade does not prevent micturition.

What concept does this question test?

It tests Local and regional anaesthesia: urinary retention after neuraxial block in Anaesthesia. Loss of detrusor contraction and sensation of bladder filling leads to retention, which is more frequent with long-acting agents, intrathecal opioids and anticholinergic drugs. Bladder scanning or catheterisation is needed.

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 Local and regional anaesthesia: urinary retention after neuraxial block?

Make a table of each agent, its key advantage and its main side effect. Then use the flashcards and the other Anaesthesia 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.