Medical disorders: anti-Ro antibodies: practice question

A OBG 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

OBG · Medical disorders: anti-Ro antibodies

Sample item

A woman with SLE who is anti-Ro positive is at 22 weeks. Fetal echocardiography shows a heart rate of 55 beats per minute with atrioventricular dissociation. What is the diagnosis and the usual mechanism?

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

The answer and the reasoning

A. Congenital complete heart block from transplacental anti-Ro (SSA) antibody damage to the conduction system

Anti-Ro and anti-La antibodies cross the placenta from about 16 weeks and injure the fetal AV node, causing congenital heart block that is usually irreversible. Surveillance with PR interval measurement between 16 and 26 weeks is done in anti-Ro positive women, and hydroxychloroquine lowers the risk. Dexamethasone is used in some centres for incomplete block.

Option by option

  • A. Congenital complete heart block from transplacental anti-Ro (SSA) antibody damage to the conduction system (correct)

    Correct. Transplacental anti-Ro antibodies cause congenital heart block.

  • B. Ebstein anomaly from lithium

    Ebstein anomaly is a structural defect associated with lithium and does not cause AV dissociation in this way.

  • C. Fetal supraventricular tachycardia

    The heart rate described is a bradycardia, not a tachycardia.

  • D. Fetal sinus bradycardia due to maternal hydroxychloroquine

    Hydroxychloroquine reduces rather than causes this risk.

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 OBG questions

Questions about this OBG question

What is the answer to this OBG question?

The best answer is A, Congenital complete heart block from transplacental anti-Ro (SSA) antibody damage to the conduction system. Anti-Ro and anti-La antibodies cross the placenta from about 16 weeks and injure the fetal AV node, causing congenital heart block that is usually irreversible.

Why is "Ebstein anomaly from lithium" not the answer?

Ebstein anomaly is a structural defect associated with lithium and does not cause AV dissociation in this way.

Why is "Fetal supraventricular tachycardia" not the answer?

The heart rate described is a bradycardia, not a tachycardia.

Why is "Fetal sinus bradycardia due to maternal hydroxychloroquine" not the answer?

Hydroxychloroquine reduces rather than causes this risk.

What concept does this question test?

It tests Medical disorders: anti-Ro antibodies in OBG. Surveillance with PR interval measurement between 16 and 26 weeks is done in anti-Ro positive women, and hydroxychloroquine lowers the risk. Dexamethasone is used in some centres for incomplete block.

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 Medical disorders: anti-Ro antibodies?

Learn management algorithms as steps: PPH, eclampsia, ectopic pregnancy. Then use the flashcards and the other OBG 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.