Lithium Teratogenicity — MRCPsych Paper B MCQ

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ModeratePerinatal PsychiatryLithium TeratogenicityMRCPsych Paper B

A woman with bipolar disorder has continued lithium treatment during early pregnancy and is now 8 weeks pregnant. Which congenital cardiac malformation is classically associated with first-trimester lithium exposure?

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Correct answer: B — Ebstein anomaly

The correct answer is **B, Ebstein anomaly**, a congenital malformation involving apical displacement of the tricuspid valve and abnormal development of the right ventricle. It is the cardiac defect especially associated with lithium exposure during early pregnancy in traditional teaching and the current lithium SmPC. Contemporary evidence indicates that lithium produces a smaller increase in absolute cardiac-malformation risk than early reports suggested, so counselling should avoid exaggerating the risk. NICE describes the magnitude of the first-trimester fetal cardiac risk as uncertain. Atrial and ventricular septal defects are common congenital abnormalities without the same characteristic lithium association. Tetralogy of Fallot and coarctation of the aorta are also not the classically recognised lithium-associated lesion.

Reference: Electronic Medicines Compendium, Lithium Carbonate Essential Pharma 250 mg film-coated tablets, Summary of Product Characteristics, section 4.6 Fertility, pregnancy and lactation, updated 21 January 2025. https://www.medicines.org.uk/emc/product/10828/smpc