Haemophilia

Haemophilia A is inherited factor VIII deficiency and haemophilia B is factor IX deficiency. Both are X linked disorders causing impaired secondary haemostasis.

Severe disease is defined by factor activity below 1% and commonly causes spontaneous haemarthroses and muscle bleeding.

• Easy bruising
• Prolonged bleeding after procedures
• Haemarthrosis
• Deep muscle haematoma
• Intracranial haemorrhage
• Prolonged bleeding after circumcision

Petechiae are uncommon because platelet function is normal.

• aPTT is usually prolonged.

• PT is normal.

• Confirm with factor VIII and factor IX assays.

• Mixing studies help distinguish factor deficiency from an inhibitor.

Replace the deficient factor promptly when significant bleeding is suspected.

Factor VIII: approximately 1 IU/kg raises factor VIII level by about 2%.

Required dose:

Body weight × desired factor rise × 0.5

Factor IX: approximately 1 IU/kg raises activity by roughly 1%, although recovery depends on product.

Treat major bleeding immediately without waiting for imaging or laboratory confirmation.

Children with severe haemophilia should receive regular prophylactic factor replacement or non factor prophylaxis such as emicizumab in haemophilia A where available.

Avoid IM injections, aspirin and NSAIDs.

Suspected intracranial haemorrhage requires immediate factor replacement before neuroimaging.