Neonatology: parvovirus B19 and fetal hydrops: practice question

A Pediatrics 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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Pediatrics · Neonatology: parvovirus B19 and fetal hydrops

Sample item

A pregnant woman has a slapped-cheek illness at 20 weeks. Ultrasound later shows fetal ascites and skin oedema with a raised middle cerebral artery velocity. Which mechanism explains the fetal anaemia?

AMaternal anti-D antibodies destroying fetal red cellsBHaemolysis from maternal ABO incompatibilityCInfection of red cell precursors, arresting erythropoiesisDFetal haemorrhage into the maternal circulation

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

The answer and the reasoning

C. Infection of red cell precursors, arresting erythropoiesis

Parvovirus B19 binds the P antigen on erythroid progenitors and halts red cell production, causing severe fetal anaemia, high-output cardiac failure and non-immune hydrops. A raised middle cerebral artery velocity indicates anaemia, and intrauterine transfusion can be life-saving.

Option by option

A. Maternal anti-D antibodies destroying fetal red cells
Alloimmune haemolysis causes immune hydrops, but the mother's illness here is viral.
B. Haemolysis from maternal ABO incompatibility
ABO incompatibility causes mild haemolysis and does not follow a maternal viral rash illness.
C. Infection of red cell precursors, arresting erythropoiesis (correct)
Correct. The virus infects erythroid progenitors, causing a fetal aplastic anaemia.
D. Fetal haemorrhage into the maternal circulation
Fetomaternal haemorrhage causes anaemia without any maternal rash illness.

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 Pediatrics question

What is the answer to this Pediatrics question?

The best answer is C, Infection of red cell precursors, arresting erythropoiesis. Parvovirus B19 binds the P antigen on erythroid progenitors and halts red cell production, causing severe fetal anaemia, high-output cardiac failure and non-immune hydrops.

Why is "Maternal anti-D antibodies destroying fetal red cells" not the answer?

Alloimmune haemolysis causes immune hydrops, but the mother's illness here is viral.

Why is "Haemolysis from maternal ABO incompatibility" not the answer?

ABO incompatibility causes mild haemolysis and does not follow a maternal viral rash illness.

Why is "Fetal haemorrhage into the maternal circulation" not the answer?

Fetomaternal haemorrhage causes anaemia without any maternal rash illness.

What concept does this question test?

It tests Neonatology: parvovirus B19 and fetal hydrops in Pediatrics. A raised middle cerebral artery velocity indicates anaemia, and intrauterine transfusion can be life-saving.

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 Neonatology: parvovirus B19 and fetal hydrops?

Memorise milestones and the vaccine schedule as tables and revise them often. Then use the flashcards and the other Pediatrics 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.