Haemodynamics: paradoxical embolism: 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 · Haemodynamics: paradoxical embolism

Sample item

A 30-year-old woman with a recent calf deep vein thrombosis develops sudden right-sided weakness and aphasia. CT shows an acute left middle cerebral artery territory infarct, and a bubble-contrast echocardiogram shows a patent foramen ovale with right-to-left passage of bubbles. What is the most likely mechanism of the stroke?

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

The answer and the reasoning

D. Venous thrombus crossing the foramen ovale into the systemic arterial circulation

A paradoxical embolus is a venous thrombus that bypasses the lungs through an interatrial or interventricular defect and lodges in a systemic artery. It is suspected when a young patient has an arterial event together with venous thrombosis and a right-to-left shunt. The shunt reverses transiently when right atrial pressure rises, for example with straining or a Valsalva manoeuvre.

Option by option

  • A. Septic vegetations from infective endocarditis of the mitral valve

    Endocarditis would give fever and septic emboli, and nothing in the vignette suggests valve infection.

  • B. Fat globules released from a long bone fracture reaching the brain

    Fat embolism follows long bone trauma and produces diffuse petechial and pulmonary features, not a focal territorial infarct.

  • C. Thrombus formed in the left atrial appendage because of atrial fibrillation

    Atrial fibrillation is not described here and would not explain the demonstrated right-to-left shunt or the venous thrombosis.

  • D. Venous thrombus crossing the foramen ovale into the systemic arterial circulation (correct)

    Correct. The deep vein thrombus passes through the patent foramen ovale and occludes a cerebral artery.

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, Venous thrombus crossing the foramen ovale into the systemic arterial circulation. A paradoxical embolus is a venous thrombus that bypasses the lungs through an interatrial or interventricular defect and lodges in a systemic artery.

Why is "Septic vegetations from infective endocarditis of the mitral valve" not the answer?

Endocarditis would give fever and septic emboli, and nothing in the vignette suggests valve infection.

Why is "Fat globules released from a long bone fracture reaching the brain" not the answer?

Fat embolism follows long bone trauma and produces diffuse petechial and pulmonary features, not a focal territorial infarct.

Why is "Thrombus formed in the left atrial appendage because of atrial fibril…" not the answer?

Atrial fibrillation is not described here and would not explain the demonstrated right-to-left shunt or the venous thrombosis.

What concept does this question test?

It tests Haemodynamics: paradoxical embolism in Pathology. It is suspected when a young patient has an arterial event together with venous thrombosis and a right-to-left shunt. The shunt reverses transiently when right atrial pressure rises, for example with straining or a Valsalva manoeuvre.

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 Haemodynamics: paradoxical embolism?

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.