Perioperative care: neuraxial block after low molecular weight heparin: 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.

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General Surgery · Perioperative care: neuraxial block after low molecular weight heparin

Sample item

A patient received enoxaparin 40 mg subcutaneously for thromboprophylaxis at 8 pm. The anaesthetist plans to insert an epidural catheter the next day. What is the minimum safe interval after the prophylactic dose?

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

The answer and the reasoning

B. 12 hours

To limit the risk of spinal haematoma, needle placement or catheter insertion should wait at least 12 hours after a prophylactic dose of low molecular weight heparin. A longer interval of 24 hours is needed after therapeutic dosing.

Option by option

  • A. 4 hours

    Four hours falls around the peak of anti-Xa activity and carries a risk of spinal haematoma.

  • B. 12 hours (correct)

    Correct. A 12-hour gap after a prophylactic dose allows anticoagulant activity to fall before neuraxial puncture.

  • C. 2 hours

    Two hours is too short, and peak anticoagulant effect occurs a few hours after injection.

  • D. 6 hours

    Six hours is still before the recommended interval for neuraxial puncture.

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.

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Questions about this General Surgery question

What is the answer to this General Surgery question?

The best answer is B, 12 hours. To limit the risk of spinal haematoma, needle placement or catheter insertion should wait at least 12 hours after a prophylactic dose of low molecular weight heparin.

Why is "4 hours" not the answer?

Four hours falls around the peak of anti-Xa activity and carries a risk of spinal haematoma.

Why is "2 hours" not the answer?

Two hours is too short, and peak anticoagulant effect occurs a few hours after injection.

Why is "6 hours" not the answer?

Six hours is still before the recommended interval for neuraxial puncture.

What concept does this question test?

It tests Perioperative care: neuraxial block after low molecular weight heparin in General Surgery. A longer interval of 24 hours is needed after therapeutic dosing.

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 Perioperative care: neuraxial block after low molecular weight heparin?

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.