Obstetric imaging: Doppler for fetal anaemia: 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.

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Radiology · Obstetric imaging: Doppler for fetal anaemia

Sample item

A woman with Rh alloimmunisation has rising antibody titres. Which noninvasive Doppler measurement best detects significant fetal anaemia?

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

The answer and the reasoning

D. Peak systolic velocity of the fetal middle cerebral artery

Anaemia lowers blood viscosity and raises cardiac output, so middle cerebral artery peak systolic velocity rises above 1.5 multiples of the median in significant anaemia. This reduces the need for amniocentesis. Uterine artery indices reflect placental resistance.

Option by option

  • A. Uterine artery pulsatility index

    Uterine artery indices assess placental perfusion in growth restriction.

  • B. Umbilical vein flow

    Umbilical vein flow is not the standard test for anaemia.

  • C. Ductus venosus a-wave

    Ductus venosus waveform relates to cardiac function and acidaemia.

  • D. Peak systolic velocity of the fetal middle cerebral artery (correct)

    Correct. A raised MCA peak systolic velocity detects fetal anaemia.

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 Radiology question

What is the answer to this Radiology question?

The best answer is D, Peak systolic velocity of the fetal middle cerebral artery. Anaemia lowers blood viscosity and raises cardiac output, so middle cerebral artery peak systolic velocity rises above 1.

Why is "Uterine artery pulsatility index" not the answer?

Uterine artery indices assess placental perfusion in growth restriction.

Why is "Umbilical vein flow" not the answer?

Umbilical vein flow is not the standard test for anaemia.

Why is "Ductus venosus a-wave" not the answer?

Ductus venosus waveform relates to cardiac function and acidaemia.

What concept does this question test?

It tests Obstetric imaging: Doppler for fetal anaemia in Radiology. 5 multiples of the median in significant anaemia. This reduces the need for amniocentesis. Uterine artery indices reflect placental resistance.

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 Obstetric imaging: Doppler for fetal anaemia?

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.