Imaging modalities and physics: venous Doppler phasicity: practice question

A Radiology 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

Radiology · Imaging modalities and physics: venous Doppler phasicity

Sample item

A patient with a swollen left leg has a compressible left popliteal vein, but Doppler of the left common femoral vein shows continuous flow without respiratory variation. Which site is most likely obstructed?

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

The answer and the reasoning

D. Left iliac vein or inferior vena cava

Respiratory phasicity in the femoral vein is transmitted through a patent proximal venous channel. A continuous, damped signal implies obstruction above the groin, in the iliac vein or IVC, which compression ultrasound of the groin cannot directly show. Calf and saphenous disease do not abolish phasicity.

Option by option

  • A. Superficial femoral vein valves

    Valve incompetence produces reflux on a Valsalva manoeuvre, not a continuous non-phasic signal.

  • B. Great saphenous vein at the knee

    Saphenous disease is superficial and does not damp the deep femoral waveform.

  • C. Calf muscular veins

    Calf vein thrombosis leaves the femoral waveform phasic.

  • D. Left iliac vein or inferior vena cava (correct)

    Correct. Loss of phasicity points to proximal iliocaval outflow obstruction.

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 Radiology questions

Questions about this Radiology question

What is the answer to this Radiology question?

The best answer is D, Left iliac vein or inferior vena cava. Respiratory phasicity in the femoral vein is transmitted through a patent proximal venous channel.

Why is "Superficial femoral vein valves" not the answer?

Valve incompetence produces reflux on a Valsalva manoeuvre, not a continuous non-phasic signal.

Why is "Great saphenous vein at the knee" not the answer?

Saphenous disease is superficial and does not damp the deep femoral waveform.

Why is "Calf muscular veins" not the answer?

Calf vein thrombosis leaves the femoral waveform phasic.

What concept does this question test?

It tests Imaging modalities and physics: venous Doppler phasicity in Radiology. A continuous, damped signal implies obstruction above the groin, in the iliac vein or IVC, which compression ultrasound of the groin cannot directly show. Calf and saphenous disease do not abolish phasicity.

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 Imaging modalities and physics: venous Doppler phasicity?

Learn signs with the image, and the disease they point to. Then use the flashcards and the other Radiology 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.