Haematology & Oncology

Haemophilia

Haemophilia is an inherited deficiency of factor VIII (haemophilia A) or factor IX (haemophilia B), causing impaired fibrin formation and a characteristic tendency to bleed into joints, muscles and deep tissues; urgent specialist treatment is needed for significant bleeding or procedures.

In a nutshell

Haemophilia A is factor VIII deficiency and haemophilia B is factor IX deficiency, usually inherited in an X-linked pattern. The phenotype is deep bleeding into joints and muscles, with an often isolated prolonged APTT. Treat significant bleeds promptly through the haemophilia centre, prevent joint damage with specialist prophylaxis, and recognise that emicizumab changes laboratory interpretation and inhibitor-bleed management.

Classic presentation

A boy or man with recurrent painful haemarthroses, deep muscle bleeding or delayed bleeding after trauma or surgery, often with an affected maternal relative and a prolonged APTT with normal PT and platelets.

Key points

Haemophilia A is factor VIII deficiency; haemophilia B is factor IX deficiency.
Bleeding is typically deep—haemarthrosis, muscle and retroperitoneal bleeding—rather than petechiae and mucosal bleeding.
A prolonged APTT suggests intrinsic-pathway disease, but mild haemophilia may have a normal screen; confirm with factor assays and specialist testing.
Significant bleeding, head injury and urgent procedures need immediate haemophilia-centre contact and the patient's documented haemostatic plan.
Prophylaxis aims to prevent bleeds and preserve joints; the product and regimen are specialist, shared decisions.
Emicizumab is prophylaxis, not routine acute-bleed treatment; it interferes with routine APTT and FVIII assays, and aPCC can be dangerous in patients receiving it.
Desmopressin is for selected responsive mild haemophilia A, not haemophilia B; tranexamic acid is an adjunct for suitable mucosal or dental bleeding.

First-line investigation

FBC, PT, APTT and fibrinogen followed by factor VIII and IX assays, inhibitor testing and genetic or carrier assessment through a specialist haemophilia laboratory; use emicizumab-compatible assays when relevant.

Management

Recognise a significant bleed and contact the centre

For head injury, severe headache, neck or airway symptoms, deep muscle or abdominal pain, shock or a major procedure, contact the haemophilia comprehensive care centre immediately and use the documented emergency haemostatic plan; do not delay urgent treatment for imaging or complete assays.^3,5

Confirm type, severity and inhibitor status

Use FBC, PT, APTT, fibrinogen, factor VIII and IX assays, inhibitor testing and genetic or carrier assessment as appropriate; interpret the results with the haemophilia laboratory, especially after recent factor or emicizumab exposure.^1,7,6

Replace the missing haemostatic activity

Give the person's prescribed factor VIII or factor IX replacement promptly for a confirmed or strongly suspected significant bleed, with product, dose, target and repeat interval determined by the haemophilia centre according to the site and severity; avoid intramuscular injections and unnecessary invasive procedures.^3,2,10
For an acute joint bleed, use early specialist haemostatic treatment, appropriate analgesia, short-term protection and expert physiotherapy; do not aspirate routinely.⁴

Manage inhibitors and critical-site bleeding

If the response to factor is unexpectedly poor, suspect an inhibitor and seek urgent specialist advice. In a patient receiving emicizumab, never choose a bypassing agent independently; aPCC has a recognised thrombotic microangiopathy and thrombosis risk, and the patient's centre must direct treatment.^8,7,6
Admit or transfer for critical-site bleeding, ongoing haemodynamic compromise, compartment syndrome, suspected intracranial bleeding or a bleed requiring repeated haemostatic therapy; coordinate imaging, surgery, anaesthesia and the haemophilia team.^3,5

Prevent future bleeds and protect joints

Offer and review prophylaxis according to severity, bleeding phenotype and joint health. Factor replacement, emicizumab and other specialist options should be selected through shared decision-making and current NHS or NICE policy; emicizumab is prophylaxis and does not remove the need for an acute-bleed plan.^2,11,12
Use a documented desmopressin response plan for suitable mild haemophilia A and tranexamic acid for appropriate mucosal or dental bleeding; arrange dental, physiotherapy, genetic, pregnancy and procedure planning through the comprehensive care MDT.^1,13,14

Exam traps

Haemophilia causes haemarthroses and deep haematomas, whereas platelet disorders and von Willebrand disease more often cause mucocutaneous bleeding.
A normal PT does not make the condition mild; PT assesses the extrinsic pathway and is usually normal.
A normal APTT does not exclude mild haemophilia; factor assays are needed when the bleeding history is convincing.
Desmopressin can help selected mild haemophilia A but does not replace factor IX in haemophilia B.
Emicizumab can make APTT-based tests misleading; ask the laboratory for an emicizumab-compatible FVIII and inhibitor assay.
Do not give activated prothrombin complex concentrate to someone on emicizumab without urgent comprehensive-care-centre direction because of thrombotic microangiopathy and thrombosis risk.
A new bleeding disorder in an adult or after pregnancy is not automatically congenital haemophilia; consider acquired factor VIII inhibition.

Illustrations

Knee haemarthrosis on MRISagittal T2-weighted MRI showing a large suprapatellar and joint effusion with synovial hypertrophy and soft-tissue swelling in haemophilic knee bleeding.Yu C et al., Frontiers in Pediatrics 2026, CC-BY-4.0 · CC-BY-4.0

X-linked recessive inheritanceA pedigree showing X-linked recessive inheritance with affected males and carrier females, illustrating the pattern of transmission.File:Autosomal recessive, Wikimedia Commons · CC-BY-SA-4.0

Key sources

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.