Obstetric anaesthesia: spinal dose requirement in pregnancy: 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 · Obstetric anaesthesia: spinal dose requirement in pregnancy

Sample item

Compared with a non-pregnant woman, how does the spinal local anaesthetic dose requirement change in pregnancy?

AIt is unchangedBIt is increased because of increased CSF volumeCIt is reduced because of epidural venous engorgement and increased neural sensitivityDIt is increased because of rapid drug metabolism

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

The answer and the reasoning

C. It is reduced because of epidural venous engorgement and increased neural sensitivity

Engorgement of epidural veins reduces the volume of CSF and the epidural space, and raised progesterone levels increase the sensitivity of nerves to local anaesthetic. The same dose therefore spreads higher and acts more intensely. Doses for neuraxial blocks are reduced accordingly.

Option by option

A. It is unchanged
A change does occur and needs dose adjustment.
B. It is increased because of increased CSF volume
CSF volume is reduced and not increased.
C. It is reduced because of epidural venous engorgement and increased neural sensitivity (correct)
Correct. Reduced CSF volume and increased sensitivity lower the dose required.
D. It is increased because of rapid drug metabolism
Metabolism is not the reason for a dose change in spinal anaesthesia.

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 C, It is reduced because of epidural venous engorgement and increased neural sensitivity. Engorgement of epidural veins reduces the volume of CSF and the epidural space, and raised progesterone levels increase the sensitivity of nerves to local anaesthetic.

Why is "It is unchanged" not the answer?

A change does occur and needs dose adjustment.

Why is "It is increased because of increased CSF volume" not the answer?

CSF volume is reduced and not increased.

Why is "It is increased because of rapid drug metabolism" not the answer?

Metabolism is not the reason for a dose change in spinal anaesthesia.

What concept does this question test?

It tests Obstetric anaesthesia: spinal dose requirement in pregnancy in Anaesthesia. The same dose therefore spreads higher and acts more intensely. Doses for neuraxial blocks are reduced accordingly.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. 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 Obstetric anaesthesia: spinal dose requirement in pregnancy?

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.