Hemophilias are bleeding disorders due to deficiency in one of
the factors present in the clotting cascade.1 The
most common factor abnormalities are of Factor VIII (hemophilia
A) or Factor IX (hemophilia B). Historically, hemophilia A was known
as “classic hemophilia” and hemophilia
B as “Christmas disease,” but
these terms are no longer in common use. von Willebrand disease (vWD)
is a related hereditary deficiency of von Willebrand factor (vWF).
These hereditary bleeding disorders typically appear early in
life, and adult patients will usually be able to relate a history
of a bleeding problem in themselves or their family. However, patients
with mild forms of inherited disease may be unaware of a bleeding
disorder until stressed by significant trauma or development of
another hemostatic problem. Because of new mutations, patients with
congenital coagulopathies may not have a family history of bleeding.
Systemic bleeding disorders should be suspected in patients with
severe bleeding related to trivial trauma or minor surgery, or spontaneous bleeding,
particularly when the bleeding occurs in joints or muscle. Unusual
bleeding or bruising at multiple areas should also raise concern about
a coagulopathy. Medications can be responsible for unmasking a mild
The pattern of bleeding can suggest a likely etiology. For example,
patients with easy bruising, gingival bleeding, epistaxis, hematuria,
GI bleeding, or heavy menses are more likely to have a deficiency
or dysfunction of the platelets. Conversely, patients with spontaneous
deep bruises, hemarthrosis, retroperitoneal bleeding, or intracranial
bleeding are more likely to have a coagulation factor deficiency.
In factor-deficient patients, bleeding associated with trauma may
be delayed. This is presumed to be due to the instability of the
initial platelet thrombus that is inadequately stabilized by fibrin
clot formation. Patients with vWD may present with features of both
platelet and clotting factor problems.
Hemophilia is a disorder of coagulation caused primarily by a
deficiency in a circulating plasma protein.1,2 Hemophilia
A is caused by a deficiency of Factor VIII and is the most common
cause of hemophilia in the U.S., affecting 1 in 10,000 males. Hemophilia
B is caused by a deficiency of Factor IX and is less common, affecting
approximately 1 in 25,000 to 35,000 males. Together, these forms
of hemophilia make up about 99% of patients with inherited
coagulation factor deficiencies. Hemophilia A and B are clinically
indistinguishable from each other, and specific factor testing must
be done to identify the specific type of hemophilia.
Both hemophilia A and B are X-linked disorders; therefore, this
is overwhelmingly a disease of men, with women typically being asymptomatic carriers.
Only rarely do women have severe disease. While these disorders
are genetic and can be inherited, a family history of bleeding may
be absent because approximately one third of new cases of hemophilia
A and one fifth of new cases of hemophilia B arise from a spontaneous