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Neonatal Lupus CHB — RACP Adult Medicine MCQ

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HardRheumatologyNeonatal Lupus CHBRACP Adult Medicine

A 30-year-old woman with anti-Ro (SSA) positive SLE is at 20 weeks gestation. She is on azathioprine and hydroxychloroquine. Fetal echo shows a fetal heart rate of 55 bpm with complete heart block. What is the most likely cause?

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Correct answer: A — Neonatal lupus with congenital heart block

Congenital heart block in a fetus of an anti-Ro/anti-La positive mother is neonatal lupus. Maternal anti-Ro antibodies cross the placenta and damage the fetal cardiac conduction system (typically at 18–24 weeks). Complete heart block is usually irreversible and may require postnatal pacemaker. Dexamethasone (crosses the placenta) may be trialled for incomplete heart block. Hydroxychloroquine reduces recurrence risk in subsequent pregnancies.

Reference: EULAR – 2024 – SLE in Pregnancy; eTG Rheumatology 2024