[Constitutional abnormalities of hemostasis: diagnostic strategy]

The most common clinical and biological expressions of constitutional abnormalities of haemostasis on which rests the diagnostic approach are influenced by the level where deficiency occurs as well as by the degree of this deficiency and its mode of transmission. Four situations encountered in practice are described: a severe form with loud and early clinical expression, a moderate form with subdued clinical expression but potential risk of haemorrhage, a genetic enquiry and the discovery of a biological abnormality. Concerning the first two situations, the stress is placed on their clinical signs, since peculiarities in a routine laboratory examination lead to a more appropriate exploration performed by a specialized laboratory.