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Educational draft · awaiting clinical reviewUse Rapid for revision, not patient-care decisions. Check current national and local guidance and the BNF or BNFC before acting.

Haemophilia A and B

Haematology and transfusion · UK scope · Sources checked 27 Aug 2026 · Clinical review pending

RapidFull
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Suspected critical-site haemophilia bleed

Head injury, neurological symptoms, neck or airway swelling, severe abdominal or back pain, haemodynamic instability, iliopsoas symptoms or a tense painful limb or joint requires treatment before imaging confirmation.

Action: Contact the haemophilia comprehensive care centre immediately, give the patient's prescribed factor VIII or IX concentrate or bypassing plan without waiting for laboratory or imaging results, use ABCDE and anatomical source control, avoid intramuscular injections and neuraxial procedures, and obtain urgent imaging after haemostatic treatment has begun.

Synopsis

Diagnose factor VIII or IX deficiency, recognise life- and joint-threatening bleeding, and coordinate factor replacement, prophylaxis, inhibitor surveillance, surgery and reproductive care through a haemophilia centre.

  • Haemophilia A is factor VIII deficiency and haemophilia B is factor IX deficiency; both usually show an isolated prolonged APTT, but mild disease can have a normal screening APTT.
  • Confirm with one-stage or chromogenic factor assays and repeat or use alternate methods when phenotype and result disagree; measure VWF to distinguish low FVIII caused by VWD.
  • Severe haemophilia is a baseline factor level below 1 IU/dL, moderate 1–5 IU/dL and mild above 5 to below 40 IU/dL; bleeding history remains essential.
  • Treat suspected intracranial, neck, gastrointestinal, iliopsoas or major traumatic bleeding immediately with the person's haemophilia-centre factor or bypassing plan before diagnostic imaging.
  • Factor VIII dosing is guided by the principle that approximately 1 IU/kg raises plasma FVIII by about 2 IU/dL; factor IX recovery is product-specific and must follow the named concentrate protocol.
  • Prophylaxis is standard for severe disease and recurrent bleeding; recombinant factor, extended-half-life products, emicizumab in haemophilia A and selected gene therapy are specialist choices.
  • An inadequate factor rise, shortened half-life or breakthrough bleeding should trigger an inhibitor assay; do not keep escalating ordinary factor without checking recovery and contacting the centre.
  • Avoid aspirin, most NSAIDs, intramuscular injections and unplanned neuraxial procedures; coordinate dental work, surgery, vaccination route, sports, fertility, pregnancy and newborn testing with the haemophilia team.

Key red flags

Any significant head injury, new headache, vomiting, confusion, weakness or seizure is an intracranial bleed until urgently treated and imaged, even if examination is initially normal.

Neck, tongue or pharyngeal swelling, voice change, stridor or dysphagia threatens the airway and requires immediate factor cover with anaesthetic and ENT support.

Groin pain, hip flexion, femoral neuropathy, falling haemoglobin or unexplained shock suggests iliopsoas or retroperitoneal bleeding requiring urgent factor treatment and imaging.

Inhibitor clue

Bleeding despite appropriately timed concentrate, low measured recovery or a rapidly falling factor level requires urgent inhibitor assessment.

Investigation priorities

01
First-line: PT, APTT, fibrinogen and FBCFirst stepFirst line

Identify an intrinsic-pathway pattern and alternative causes of bleeding or anaemia.

Management branches

New suspected haemophiliaConfirm factor deficiency

A male or female has deep, delayed or procedure-related bleeding with a compatible pedigree or isolated APTT abnormality.

  1. Record lifelong bleeding and haemostatic challenges, construct a pedigree and check FBC, PT, APTT and fibrinogen.
  2. Measure factor VIII, factor IX and VWF antigen and activity, using mixing and alternative assays when results are discordant.
  3. Refer to a haemophilia centre for confirmation, genetic testing, family screening, emergency card and a preventive treatment plan.

Key medicines

Recombinant factor VIII concentrateUse the patient's named product and pharmacokinetic plan; for standard factor VIII, required IU is approximately body weight in kg × desired FVIII rise in IU/dL × 0.5, repeated according to measured recovery, half-life, bleed site and healing duration.Treat critical bleeding before assays, but check recovery afterwards. Products and extended-half-life intervals are not interchangeable; monitor inhibitor development, thrombosis in high target states, hypersensitivity and central-access complications.
Recombinant factor IX concentrateUse the exact named product SmPC and individual recovery; calculate units from body weight and desired FIX rise, then repeat by measured level because standard- and extended-half-life concentrates have materially different incremental recovery and intervals.Avoid a generic one-size conversion between products. Monitor factor levels, inhibitor or anaphylaxis risk, thrombosis at high exposure and renal or hepatic comorbidity that changes procedural risk.
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Sources and review status5 sources · checked 27 Aug 2026 · clinical review pending+
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.

  • UK Haemophilia Centre Doctors' Organisation guidelinesUK haemophilia diagnosis, factor, prophylaxis, inhibitor and comprehensive-care guidance collection.
  • NHS: treatment for haemophiliaNational patient pathway for preventive and on-demand haemophilia treatment.
  • Hemlibra 30 mg/mL Summary of Product CharacteristicsLicensed emicizumab loading, maintenance schedules and bypassing-agent safety.
  • BSH: prophylactic factor replacement for children and adults with haemophilia A and BUK individualised factor prophylaxis, pharmacokinetic and bleed-prevention guidance.
  • BNF desmopressin monographUK desmopressin dosing and fluid and sodium precautions.

Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes

Authoring stateRapid draftClinical stateAwaiting reviewJurisdictionUnited Kingdom