Neonatology: neonatal alloimmune thrombocytopenia: 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.

Try it

Pediatrics · Neonatology: neonatal alloimmune thrombocytopenia

Sample item

A term baby has petechiae on day 1 with a platelet count of 15,000 per microlitre and is otherwise well. The mother has a normal platelet count and no history of ITP. What is the most likely cause?

AMaternal alloantibodies against a paternal platelet antigenBNeonatal disseminated intravascular coagulationCThrombocytopenia with absent radiiDMaternal autoimmune thrombocytopenia

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

The answer and the reasoning

A. Maternal alloantibodies against a paternal platelet antigen

In neonatal alloimmune thrombocytopenia a platelet antigen-negative mother makes IgG against a paternal antigen, commonly HPA-1a in Western series, which crosses the placenta and destroys fetal platelets. The mother's own count is normal, and intracranial haemorrhage is the main risk. Treatment is transfusion of antigen-negative platelets, with IVIG as support.

Option by option

A. Maternal alloantibodies against a paternal platelet antigen (correct)
Correct. Alloimmunisation against a paternal platelet antigen with a normal maternal count is typical.
B. Neonatal disseminated intravascular coagulation
DIC would be seen in a sick, septic baby with abnormal coagulation tests.
C. Thrombocytopenia with absent radii
TAR syndrome has absent radii on examination, which is not described.
D. Maternal autoimmune thrombocytopenia
Maternal autoimmune thrombocytopenia would show a low maternal platelet count.

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 A, Maternal alloantibodies against a paternal platelet antigen. In neonatal alloimmune thrombocytopenia a platelet antigen-negative mother makes IgG against a paternal antigen, commonly HPA-1a in Western series, which crosses the placenta and destroys fetal platelets.

Why is "Neonatal disseminated intravascular coagulation" not the answer?

DIC would be seen in a sick, septic baby with abnormal coagulation tests.

Why is "Thrombocytopenia with absent radii" not the answer?

TAR syndrome has absent radii on examination, which is not described.

Why is "Maternal autoimmune thrombocytopenia" not the answer?

Maternal autoimmune thrombocytopenia would show a low maternal platelet count.

What concept does this question test?

It tests Neonatology: neonatal alloimmune thrombocytopenia in Pediatrics. The mother's own count is normal, and intracranial haemorrhage is the main risk. Treatment is transfusion of antigen-negative platelets, with IVIG as support.

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 Neonatology: neonatal alloimmune thrombocytopenia?

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.