Renal: micturition after spinal injury: practice question

A Physiology 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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Physiology · Renal: micturition after spinal injury

Sample item

A 30-year-old man had a complete T8 spinal cord transection 6 months ago. Initially his bladder was atonic with retention. Which describes his bladder now?

APersistent atonic bladder with overflow incontinenceBAutomatic bladder emptying by the sacral reflex without voluntary controlCComplete loss of the micturition reflex arcDNormal voluntary voiding through pontine control

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

The answer and the reasoning

B. Automatic bladder emptying by the sacral reflex without voluntary control

Micturition is a sacral S2-S4 reflex: stretch afferents travel in the pelvic nerve and parasympathetic efferents contract the detrusor. After spinal shock passes, the intact sacral arc returns and the bladder empties reflexly when filled, often with detrusor-sphincter dyssynergia. Voluntary control needs the pontine centre, which is disconnected.

Option by option

A. Persistent atonic bladder with overflow incontinence
Atonia is typical of spinal shock or a lesion damaging the sacral arc.
B. Automatic bladder emptying by the sacral reflex without voluntary control (correct)
Correct. A spastic reflex bladder develops once spinal shock resolves.
C. Complete loss of the micturition reflex arc
The sacral reflex arc lies below the injury and is intact.
D. Normal voluntary voiding through pontine control
The pontine centre and cortex cannot influence the sacral cord after complete transection.

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 Physiology question

What is the answer to this Physiology question?

The best answer is B, Automatic bladder emptying by the sacral reflex without voluntary control. Micturition is a sacral S2-S4 reflex: stretch afferents travel in the pelvic nerve and parasympathetic efferents contract the detrusor.

Why is "Persistent atonic bladder with overflow incontinence" not the answer?

Atonia is typical of spinal shock or a lesion damaging the sacral arc.

Why is "Complete loss of the micturition reflex arc" not the answer?

The sacral reflex arc lies below the injury and is intact.

Why is "Normal voluntary voiding through pontine control" not the answer?

The pontine centre and cortex cannot influence the sacral cord after complete transection.

What concept does this question test?

It tests Renal: micturition after spinal injury in Physiology. After spinal shock passes, the intact sacral arc returns and the bladder empties reflexly when filled, often with detrusor-sphincter dyssynergia. Voluntary control needs the pontine centre, which is disconnected.

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 Renal: micturition after spinal injury?

For each system, sketch the key graph (pressure–volume loop, oxygen dissociation curve, nephron handling) and explain it aloud. Then use the flashcards and the other Physiology 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.