Bleeding disorders

Bleeding disorders

Bleeding disorders can be due to qualitative or quantitative abnormalities in either platelets or coagulation factors. Clinical manifestations often point to the underlying cause of excessive bleeding. The general rule is:

Bleeding into the skin and mucous membranes: ecchymoses, epistaxis, petechiae, gastrointestinal or genitourinary bleeding are suggestive of platelet disorders.
Bleeding into the joints or the retroperitoneum suggest coagulation factor abnormalities or warfarin toxicity.
Bleeding into both joints and mucocutaneous tissue can suggest disseminated intravascular coagulation (DIC).

The most common reason for bleeding is thrombocytopenia. Thrombocytopenia refers to a lower than usual number of platelets. Decreased platelet production or increased platelet destruction can result in thrombocytopenia. Bone marrow disease, side effects from drugs such as antineoplastics, and some infectious diseases can result in a decreased platelet count.

Idiopathic thrombocytopenic purpura (ITP) is a condition in which antibodies form against platelets. Patients with bleeding disorders due to platelet problems often experience immediate bleeding after trauma. The bleeding usually affects the skin, mucous membranes, nose, and urinary and gastrointestinal tracts. Bleeding may range from small petechiae to large ecchymotic areas.

Von Willebrand's disease is the most common hereditary coagulation disorder. It occurs in about 1% of the general population. Many cases go undiagnosed due to the mild nature of the bleeding which is often masked by an acute trauma. Deficiency or molecular defects in vWF result in problems with platelet adhesion. Adhesion is necessary for the activation of platelets.

Hemophilia is a X chromosome linked recessive trait that is the result of deficiency in the production of factors VIII or IX. Factor VIII deficiency (hemophilia A) can also be acquired as a result of the development of VIII inhibitors. Liver transplant corrects factor VIII deficiency in inherited hemophilia.

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The most common hereditary disorder causing excessive bleeding is Hemophilia A.

Disseminated intravascular coagulation or DIC occurs as a result of obstetric complications such as abruptio placenta, saline abortion, retained products of conception, amniotic fluid embolism or severe pre-eclampsia/eclampsia. Other causes of DIC are septicemia, malignancies, cirrhosis of the liver, sickle cell disease, trauma or crushing injuries, snake bite, extracorporeal bypass, and incompatible blood transfusions. DIC, also known as consumption coagulopathy, is the result of continuous production of thrombin. The abnormal production of thrombin consumes the other clotting factors, leading to uncontrolled bleeding. DIC is always secondary to some other disease process, and begins when widespread tissue injury triggers blood clotting.

DIC produces multiple coagulation test abnormalities, including:

Prolonged PT and PTT times
Prolonged bleeding time
Decreased fibrinogen and platelet count
Increased fibrinolysin
Positive fibrin split products
Prolonged thrombin time
Decreased clotting factors II, V, VII, and X

To reverse DIC, the underlying problem stimulating coagulation must always be treated. Paradoxically, in some situations, the treatment for uncontrolled bleeding in DIC is heparin administration. Heparin blocks thrombin formation, which then blocks consumption of the other clotting factors and results in hemostasis.

The Virtual Hospital website has a great deal of information on bleeding disorders and coagulation tests. Please explore, and be prepared to answer the following question:

In addition to PT (INR), PTT, platelet count, bleeding time, and fibrin split products, what other test can be performed to test for byproducts of clot breakdown?