Haematology: aspirin and platelet function: practice question

A Pathology 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

Pathology · Haematology: aspirin and platelet function

Sample item

A 50-year-old woman on daily low-dose aspirin has frequent nosebleeds and easy bruising. Platelet count, PT and aPTT are normal, but bleeding time is prolonged. Which mechanism accounts for this?

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

The answer and the reasoning

B. Irreversible acetylation of platelet cyclooxygenase-1

Aspirin irreversibly acetylates COX-1 in platelets. Platelets cannot make new enzyme, so thromboxane A2 production is lost for the life of the platelet, impairing aggregation and prolonging bleeding time.

Option by option

  • A. Blockade of the platelet ADP receptor by a thienopyridine

    ADP receptor blockade is the action of clopidogrel and related drugs, not aspirin.

  • B. Irreversible acetylation of platelet cyclooxygenase-1 (correct)

    Correct. Platelet COX-1 acetylation abolishes thromboxane A2 synthesis for the platelet's lifespan.

  • C. Inhibition of vitamin K epoxide reductase

    Vitamin K epoxide reductase inhibition is the action of warfarin, which prolongs the PT.

  • D. Neutralisation of thrombin by antithrombin

    Neutralising thrombin through antithrombin is the action of heparin, which prolongs the aPTT.

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 Pathology questions

Questions about this Pathology question

What is the answer to this Pathology question?

The best answer is B, Irreversible acetylation of platelet cyclooxygenase-1. Aspirin irreversibly acetylates COX-1 in platelets.

Why is "Blockade of the platelet ADP receptor by a thienopyridine" not the answer?

ADP receptor blockade is the action of clopidogrel and related drugs, not aspirin.

Why is "Inhibition of vitamin K epoxide reductase" not the answer?

Vitamin K epoxide reductase inhibition is the action of warfarin, which prolongs the PT.

Why is "Neutralisation of thrombin by antithrombin" not the answer?

Neutralising thrombin through antithrombin is the action of heparin, which prolongs the aPTT.

What concept does this question test?

It tests Haematology: aspirin and platelet function in Pathology. Platelets cannot make new enzyme, so thromboxane A2 production is lost for the life of the platelet, impairing aggregation and prolonging bleeding time.

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 Haematology: aspirin and platelet function?

Learn each disease as a bundle: cause, key histology, markers, and the clinical hallmark. Then use the flashcards and the other Pathology 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.