8: Bleeding Disorders

CHIEF COMPLAINT

CONSTRUCTING A DIFFERENTIAL DIAGNOSIS

The framework for bleeding distinguishes between structural causes (ie, an injury to the tissue or organ), platelet-related causes, and clotting factor–related causes. Bleeding due to platelet abnormalities, whether due to reduced number or abnormal function of platelets, is usually small vessel bleeding, and produces such findings as petechiae, bruising, gum bleeding, or nosebleeds. The bleeding occurs immediately upon the injury that induces it. Platelet-related bleeding is generally not quantitatively significant (ie, platelet-related bleeding tends not to cause serious blood loss requiring red cell transfusions). Nonetheless, platelet-related bleeding can still be clinically important if a patient bleeds a small amount into the brain (unusual unless the platelet count is < 10,000/mcL) or induces an abdominal hematoma from vigorous coughing, for example. By contrast, bleeding due to coagulation factor deficiencies or inhibitors tends to be delayed; that is, a platelet plug slows or stops the bleeding immediately after an injury, but the platelet plug is then not bolstered by the stable fibrin clot that is meant to definitively stop the bleeding. Bleeding due to coagulation factor abnormalities is more likely to be quantitatively significant, generally occurring in joints, the gastrointestinal tract, brain, retroperitoneum, or at sites of recent injury or medical or surgical intervention.

1. Structural causes

   1. Tissue injury from trauma

   2. Abnormality of the tissue such that minor trauma causes bleeding, such as a toothbrush causing gum bleeding from inflammatory gingival disease

2. Bleeding due to platelet disorders

   1. Disorders of platelet number (thrombocytopenia)

      1. Decreased production of platelets

         • (1) Medications (examples include valproic acid, linezolid, thiazide diuretics, gold compounds, antineoplastic chemotherapy drugs)

         • (2) Bone marrow replacement by malignancy, fibrosis, granulomas

         • (3) Bone marrow aplasia

         • (4) Alcohol

         • (5) B₁₂ deficiency

      2. Increased loss or consumption of platelets

         • (1) Splenic sequestration

         • (2) Autoimmune thrombocytopenia

           • (a) Idiopathic (also called idiopathic thrombocytopenic purpura [ITP])

           • (b) HIV

           • (c) Systemic lupus erythematosus (SLE)

           • (d) Lymphoproliferative disorders

           • (e) Medications (examples include heparin, phenytoin, carbamazepine, sulfonamides, quinine, antiplatelet drugs used for coronary syndromes such as abciximab or tirofiban)

         • (3) Disseminated intravascular coagulation (DIC)

         • (4) Thrombotic thrombocytopenic purpura (TTP)

         • (5) Sepsis

   2. Disorders of platelet function

      1. Congenital

         • (1) von Willebrand disease

         • (2) Other rare genetic abnormalities

      2. Acquired

         • (1) Medications, such as aspirin, nonsteroidal antiinflammatory drugs (NSAIDs)

         • (2) Myeloproliferative disorders, such as essential thrombocythemia, polycythemia vera

         • (3) Coating of platelets by abnormal proteins, such as in multiple myeloma and, occasionally, immune thrombocytopenia

         • (4) Uremia

3. Bleeding due to clotting factor abnormalities

   1. Congenital

      1. Hemophilia A (the most common)

      2. Other clotting factor deficiencies

   2. Acquired

      1. Deficiency of a factor or factors

         • (1) Liver disease

         • (2) Vitamin K deficiency (nutritional or due to warfarin therapy)

         • (3) Abnormal adsorption of a factor, eg, factor X adsorption to amyloid fibrils

         • (4) Consumption of ...