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B12 Deficiency Post-Bypass Neuraxial Risk — FRCA Final MCQ

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ModeratePreoperative AssessmentB12 Deficiency Post-Bypass Neuraxial RiskFRCA Final

A 40-year-old woman (ASA II) with a history of gastric bypass surgery 3 years ago presents for laparoscopic cholecystectomy. She takes vitamin B12 injections and iron supplements. What specific nutritional deficiency may affect anaesthesia?

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Correct answer: E — Vitamin B12 deficiency causing subacute combined degeneration – increased risk of neurological complications from neuraxial anaesthesia

Post-gastric bypass patients commonly develop vitamin B12 deficiency (due to reduced intrinsic factor production from the bypassed stomach). Severe B12 deficiency causes subacute combined degeneration of the spinal cord (demyelination of the posterior and lateral columns). This is theoretically relevant to neuraxial anaesthesia as local anaesthetics may exacerbate damage to already demyelinated nerves (similar to the concerns with multiple sclerosis). B12 levels should be checked and deficiency corrected before elective neuraxial procedures. Other deficiencies: iron, folate, calcium, and vitamin D are also common post-bypass.

Reference: RCOA – 2023 – Bariatric anaesthesia: nutritional considerations; AAGBI – 2015 – Obesity guidelines