Haemophilia B Factor IX Target Surgery — FRCA Final MCQ

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ModeratePreoperative AssessmentHaemophilia B Factor IX Target SurgeryFRCA Final

A 40-year-old man with haemophilia B (Christmas disease, factor IX deficiency) requires emergency appendicectomy. The haematology team advise factor IX replacement. The target factor IX level for major surgery is:

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Correct answer: E — 80-100%

Haemophilia B (factor IX deficiency) requires factor IX replacement to 80-100% for major surgery (same as haemophilia A). Recombinant FIX or plasma-derived FIX concentrate is used. Dosing: required rise (IU/dL) × weight (kg) × 0.7 (FIX has a larger volume of distribution than FVIII). FIX has a longer half-life (~18-24 hours) than FVIII (~8-12 hours), so dosing intervals are longer. Post-operative levels should be maintained >50% for 7-14 days. Haematology team must be involved throughout.

Reference: BSH – 2020 – Haemophilia management; RCOA – 2023 – Haematological disorders