How does the disease present and what are the laboratory findings?
The most common clinical presentation of hemophilia A is hemarthroses. Typically in infants, as ambulation begins, bleeding into joints and muscles occurs even after minor trauma. Up to 90% of patients with severe disease demonstrate evidence of bleeding by 1 year of life. Of note is the fact that although factor VIII does not cross the placenta, newborns will often not exhibit symptoms.
Bleeding associated with hemophilia A can occur virtually anywhere in the body and give rise to secondary complications. Bleeding in the neck or pharynx may cause airway obstruction. Central nervous system hemorrhages, although uncommon, may be life-threatening and are a common cause of death.
Prolonged and excessive bleeding associated with even minor surgery is common and can be present in mild disease where there may be no history of previous sponta-neous or surgical bleeding. The importance of identifying the severity of the deficient factor is therefore underscored. In fact, the diagnosis should be suspected in any male with unusual bleeding. The laboratory data consistent with the diagnosis are a prolonged activated partial thrombo-plastin time (PTT), a normal platelet count, and normal prothrombin time (PT). Specific assay for factor VIII activity confirms and quantifies the disease.