Haematology: delayed haemolytic transfusion reaction: 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.

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Pathology · Haematology: delayed haemolytic transfusion reaction

Sample item

A multiparous 60-year-old woman receives two units of red cells. Her pretransfusion antibody screen was negative. Eight days later she has fever, jaundice and a fall in haemoglobin. The direct antiglobulin test is now positive and an antibody against a Kidd antigen is found. What is the mechanism?

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

The answer and the reasoning

D. Anamnestic antibody response against a minor red cell antigen, causing extravascular haemolysis

Prior sensitisation by pregnancy leaves antibody levels too low to detect before transfusion. Re-exposure triggers a memory response within days, and coated cells are cleared in the spleen and liver, so haemolysis is delayed and mainly extravascular.

Option by option

  • A. Preformed IgM against A or B antigens, causing complement-mediated intravascular haemolysis

    This describes an acute ABO-incompatible reaction, which occurs within minutes to hours rather than days.

  • B. Recipient antibodies against donor leucocytes, causing cytokine-mediated fever

    This describes a febrile non-haemolytic reaction, in which there is no haemolysis and the direct antiglobulin test is negative.

  • C. Donor T lymphocytes attacking recipient marrow and skin

    This describes transfusion-associated graft-versus-host disease, which is not an antibody-mediated haemolysis.

  • D. Anamnestic antibody response against a minor red cell antigen, causing extravascular haemolysis (correct)

    Correct. A memory response to a low-frequency antigen such as Kidd produces IgG that coats cells and causes delayed extravascular haemolysis.

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 Pathology question

What is the answer to this Pathology question?

The best answer is D, Anamnestic antibody response against a minor red cell antigen, causing extravascular haemolysis. Prior sensitisation by pregnancy leaves antibody levels too low to detect before transfusion.

Why is "Preformed IgM against A or B antigens, causing complement-mediated in…" not the answer?

This describes an acute ABO-incompatible reaction, which occurs within minutes to hours rather than days.

Why is "Recipient antibodies against donor leucocytes, causing cytokine-media…" not the answer?

This describes a febrile non-haemolytic reaction, in which there is no haemolysis and the direct antiglobulin test is negative.

Why is "Donor T lymphocytes attacking recipient marrow and skin" not the answer?

This describes transfusion-associated graft-versus-host disease, which is not an antibody-mediated haemolysis.

What concept does this question test?

It tests Haematology: delayed haemolytic transfusion reaction in Pathology. Re-exposure triggers a memory response within days, and coated cells are cleared in the spleen and liver, so haemolysis is delayed and mainly extravascular.

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 Haematology: delayed haemolytic transfusion reaction?

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.