Haematology: antiphospholipid syndrome: 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: antiphospholipid syndrome

Sample item

A 29-year-old woman has had three first-trimester miscarriages and an earlier deep vein thrombosis. Her aPTT is prolonged and does not correct when mixed 1:1 with normal plasma. She has no bleeding. What is the most likely explanation?

AFactor VIII deficiencyBVon Willebrand diseaseCLupus anticoagulant, an antiphospholipid antibodyDContamination of the sample with heparin only

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

The answer and the reasoning

C. Lupus anticoagulant, an antiphospholipid antibody

Lupus anticoagulant antibodies bind phospholipid-protein complexes and prolong phospholipid-dependent tests such as aPTT in vitro. Mixing with normal plasma does not correct the result, because an inhibitor is present. In vivo they cause thrombosis and recurrent pregnancy loss, so this is a prothrombotic condition. Confirmation uses dRVVT, anticardiolipin and anti-beta-2-glycoprotein I antibodies, and treatment is anticoagulation.

Option by option

A. Factor VIII deficiency
Factor VIII deficiency corrects on mixing and causes bleeding, which she does not have.
B. Von Willebrand disease
Von Willebrand disease also corrects on mixing and causes mucosal bleeding.
C. Lupus anticoagulant, an antiphospholipid antibody (correct)
Correct. A non-correcting aPTT with thrombosis and fetal loss indicates antiphospholipid antibody syndrome.
D. Contamination of the sample with heparin only
Heparin contamination would not explain the history of thrombosis and recurrent miscarriage.

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 Pathology question

What is the answer to this Pathology question?

The best answer is C, Lupus anticoagulant, an antiphospholipid antibody. Lupus anticoagulant antibodies bind phospholipid-protein complexes and prolong phospholipid-dependent tests such as aPTT in vitro.

Why is "Factor VIII deficiency" not the answer?

Factor VIII deficiency corrects on mixing and causes bleeding, which she does not have.

Why is "Von Willebrand disease" not the answer?

Von Willebrand disease also corrects on mixing and causes mucosal bleeding.

Why is "Contamination of the sample with heparin only" not the answer?

Heparin contamination would not explain the history of thrombosis and recurrent miscarriage.

What concept does this question test?

It tests Haematology: antiphospholipid syndrome in Pathology. Mixing with normal plasma does not correct the result, because an inhibitor is present. In vivo they cause thrombosis and recurrent pregnancy loss, so this is a prothrombotic condition. Confirmation uses dRVVT, anticardiolipin and anti-beta-2-glycoprotein I antibodies, and treatment is anticoagulation.

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: antiphospholipid syndrome?

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.