An 8-day-old baby bleeds excessively at circumcision.
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(a) What further tests do you require?
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Correct answer:
(a) Blood count to assess platelet numbers.
(b) Coagulation studies, prothrombin time (PT) and activated partial thromboplastin time (APTT).
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(b) What results will these show if the boy has haemophilia?
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Correct answer:
Normal platelet count and PT. Prolonged APTT.
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(c) How would you distinguish haemophila A (factor 8 deficiency) from haemophilia B (factor 9 deficiency)?
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Correct answer:
Tests for correction of APTT with a mixture of patient plasma and factor 8 or 9 deficient plasma. Factor 8 deficient plasma corrects the APTT result only in factor 9 deficiency; factor 9 deficient plasma corrects the APTT only in factor 8 deficient plasma.
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(d) At what level of factor 8 would this be classified as severe haemophilia?
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Correct answer:
Less than 1% is severe, 1–5% moderate disease, >5% mild disease.
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(e) Is the mother of this boy necessarily a carrier?
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Correct answer:
She is likely to be a carrier but about 25% of cases of haemophilia A are due to new mutations of the factor 8 gene with the mother not being a carrier.
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(f) How is the bleeding to be managed?
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Correct answer:
Infusion of factor 8. Recombinant factor 8 is preferred in a child. DDAVP may be given for mild bleeding (see Chapter 42).
