Anaesthetic Teratogenicity — FRCA Final MCQ

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ModerateObstetric AnaesthesiaAnaesthetic TeratogenicityFRCA Final

A 38-year-old woman at 16 weeks' gestation requires an emergency appendicectomy under general anaesthesia. During consent, she asks about the risk of birth defects from inhalational anaesthetic agents. Which of the following has been proven to cause structural congenital malformations in humans when used at usual clinical anaesthetic concentrations?

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Correct answer: E — None of these agents

The correct answer is E. No commonly used inhalational anaesthetic agent has been proven to cause structural congenital malformations in humans at usual clinical concentrations. Nitrous oxide is the most plausible distractor: it oxidises cobalamin and inhibits methionine synthase, impairing folate-dependent nucleotide synthesis. Prolonged, high-concentration exposure is teratogenic in animal models, and high occupational exposure has been associated with adverse reproductive outcomes, but this does not establish human teratogenicity after routine anaesthesia. Sevoflurane, isoflurane and desflurane likewise have no proven human teratogenic effect. Necessary emergency surgery should therefore proceed, with emphasis on maintaining maternal oxygenation, normocapnia, blood pressure and uteroplacental perfusion rather than selecting an agent on the basis of an unproven difference in teratogenicity.

Reference: Reitman E, Flood P. Anaesthetic considerations for non-obstetric surgery during pregnancy. British Journal of Anaesthesia. 2011;107(Suppl 1):i72-i78. https://pubmed.ncbi.nlm.nih.gov/22156272/