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Haemophilia and von Willebrand disease
In haemophilia (factor VIII or IX deficiency, X-linked) bleeding goes into joints and muscles and only the aPTT is prolonged; in von Willebrand disease (the commonest inherited bleeding disorder) bleeding comes from skin and mucosa — nose, gums and heavy periods — and desmopressin helps in type 1.
Why it matters in the exam
Two questions recur. In the first, an 18-month-old who has started walking arrives with a swollen painful knee without significant trauma, or an infant bleeds heavily after circumcision; a prolonged aPTT with normal PT and platelets — haemophilia. In the second, a girl with heavy periods from menarche, nosebleeds and prolonged bleeding after a tooth extraction — von Willebrand disease, and the work-up is VWF antigen, VWF activity and factor VIII.
Haemophilia severity is set by factor level: severe below 1%, moderate 1–5% and mild 5–40%. In severe haemophilia regular prophylaxis is given — factor replacement or emicizumab (a subcutaneous antibody that mimics factor VIII in haemophilia A). In life-threatening bleeding (intracranial) factor is given at once, before imaging. Intramuscular injections, aspirin and NSAIDs are avoided. Antibodies against the factor (inhibitors) complicate treatment and need bypassing agents.
In von Willebrand disease, type 1 (partial quantitative deficiency) is the commonest and responds to desmopressin; type 2 is a qualitative defect; type 3 is an almost complete deficiency with severe bleeding. Tranexamic acid is effective for mucosal bleeding and heavy periods. Desmopressin requires fluid restriction because of hyponatraemia, and is usually avoided under 2 years. A prolonged aPTT that corrects on a mixing study — factor deficiency; one that does not correct — an inhibitor.
Key points
- Haemophilia: X-linked, isolated prolonged aPTT, joint bleeding.
- Severity: severe below 1% factor.
- Severe haemophilia: prophylaxis; emicizumab in haemophilia A.
- von Willebrand: the commonest inherited bleeding disorder; mucosal bleeding.
- Type 1 responds to desmopressin; tranexamic acid for mucosal bleeding.
Summary table
| Disease | Inheritance and laboratory | Typical bleeding | Treatment |
|---|---|---|---|
| Haemophilia A | X-linked, low factor VIII, prolonged aPTT, normal PT and platelets | Joints, muscles, after circumcision, intracranial | Factor VIII, emicizumab for prophylaxis; desmopressin in mild disease |
| Haemophilia B | X-linked, low factor IX | As in A | Factor IX |
| von Willebrand type 1 | Autosomal dominant, partially low VWF | Nose, gums, heavy periods, after extraction | Desmopressin, tranexamic acid |
| von Willebrand type 2 | Qualitative defect, low activity-to-antigen ratio | Mucosal | VWF concentrate; desmopressin not in every subtype |
| von Willebrand type 3 | Almost absent VWF, low factor VIII | Severe bleeding, including joints | VWF concentrate |
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Sources
- WFH Guidelines for the Management of Hemophilia, 3rd edition (2020) — Factor replacement, prophylaxis and inhibitors
- ASH ISTH NHF WFH Guidelines on the Diagnosis and Management of von Willebrand Disease, 2021 — Diagnostic thresholds and treatment
- Nelson Textbook of Pediatrics, 22nd edition (2024) — Hemophilia; von Willebrand Disease
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.