The Laboratory Diagnosis of Haemophilia.

Haemophilia is the only recognized haemorrhagic diathesis which is inherited as a sex linked recessive character. It is a disease of males which is transmitted through apparently unaffected females. The classical case can be recognized with certainty since the laboratory manifestations are specific. The association of a prolonged coagulation time with a normal bleeding time and platelet count, if combined with a family history of a bleeding tendency, can hardly ever lead to any other diagnosis. During an investigation of the nature of the defect in haemophilia it was possible to examine a large number of cases of haemorrhagic disease. It soon became apparent that the laboratory diagnosis of the haemophilic state was not as simple as had at first been assumed. Of the cases which had a familial and clinical history resembling haemophilia, many had typical laboratory findings, yet in other apparently similar cases it was difficult to obtain laboratory confirmation of the disease. Accordingly, it seemed worth while to review the pathological findings in haemophilia in an attempt to assess their significance and value in diagnosis. It is these observations which form the basis of this paper.