Diagnostic Evaluation
Overt, prolonged hemorrhage is readily apparent; bleeding into tissues is less apparent (BOX 26-5). The diagnosis is usually made from a history of bleeding episodes, evidence of X-linked inheritance (only one third of the cases are new mutations), and laboratory findings. The tests specific for hemophilia plasma depend on specific factors for a reaction to occur, such as the partial thromboplastin time (PTT). Specific determination of factor deficiencies requires assay procedures normally performed in specialized laboratories. Carrier detection is possible in classic hemophilia using deoxyribonucleic acid (DNA) testing and is an important consideration in families in which female offspring may have inherited the trait.