Haemophilia B — MFDS Part 1 MCQ

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EasyHuman DiseaseHaemophilia BMFDS Part 1

A patient with haemophilia B is planned for a dental extraction. The haemophilia team decides that clotting-factor replacement is required for peri-operative haemostatic cover. Which clotting factor should be replaced?

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Correct answer: E — Factor IX

Haemophilia B, also called Christmas disease, is caused by congenital factor IX deficiency; therefore, when factor replacement is indicated for dental extraction, factor IX is replaced. The required product, dose and timing must be determined with the haemophilia team according to disease severity, measured factor activity, bleeding phenotype and procedure. Factor VIII deficiency causes haemophilia A. Factor XI deficiency is a separate inherited bleeding disorder, while factor VII deficiency affects the extrinsic coagulation pathway. Von Willebrand factor replacement is used for selected patients with von Willebrand disease rather than uncomplicated haemophilia B. The original key was correct, but the teaching statement that factor IX is invariably required before invasive dental procedures was too categorical.

Reference: Takeda UK Ltd. RIXUBIS Summary of Product Characteristics, sections 4.1, 4.2 and 5.1; text revised 18 December 2025. https://www.medicines.org.uk/emc/product/11038/smpc