Differentiation Of Bleeding Disorders

Differences Between Platelet And Coagulation Disorders

Bleeding Patterns And Clinical Presentation

Pathophysiology Of Hemostasis

Cellular Phase

• Involves platelets and vascular wall.
• Culminates in generation of hemostatic plug.
• Requires von Willebrand factor to tether platelets to injured subendothelium.
• Defects cause immediate mucocutaneous bleeding.

Fluid Phase

• Involves plasma proteins.
• Multiple-step zymogen pathway leads to thrombin generation.
• Extrinsic pathway serves as primary initiating pathway.
• Intrinsic system functions as regulatory amplification loop.
• Thrombin induces formation of insoluble fibrin clot.
• Fibrinolytic mechanisms limit clot propagation.
• Defects prevent stabilization of platelet plug, causing delayed deep bleeding.

Etiological Classification

Platelet Disorders

• Immune Destruction: Immune thrombocytopenic purpura (ITP) features autoantibodies against platelet glycoproteins.
• Microangiopathic Consumption: Hemolytic uremic syndrome, thrombotic thrombocytopenic purpura, disseminated intravascular coagulation.
• Production Defects: Congenital amegakaryocytic thrombocytopenia, aplastic anemia, Fanconi anemia.
• Qualitative Inherited Defects: Glanzmann thrombasthenia (abnormal glycoprotein IIb/IIIa), Bernard-Soulier syndrome (abnormal glycoprotein Ib).
• Medications: Aspirin, valproate, penicillins.

Coagulation Disorders

• Inherited Deficiencies: Hemophilia A (factor VIII), Hemophilia B (factor IX), von Willebrand disease.
• Acquired Deficiencies: Liver disease impairs synthesis of procoagulant factors.
• Vitamin K Deficiency: Impairs carboxylation of factors II, VII, IX, X.
• Consumption: Disseminated intravascular coagulation depletes multiple clotting factors simultaneously.
• Acquired Inhibitors: Autoantibodies target specific coagulation factors.

Diagnostic Evaluation

Primary Screening Tests

• Complete Hemogram: Evaluates platelet count, assesses red cell morphology for microangiopathy.
• Bleeding Time: Prolonged if platelet count falls below 100,000/μL or in functional defects; lacks reproducibility.
• Prothrombin Time (PT): Evaluates extrinsic and common pathways.
• Activated Partial Thromboplastin Time (aPTT): Evaluates intrinsic and common pathways.
• Thrombin Time (TT): Detects hypofibrinogenemia or dysfibrinogenemia.

Advanced Coagulation And Platelet Assays

• Mixing Studies: Differentiate factor deficiency (corrects) from acquired inhibitors (fails to correct).
• Platelet Aggregation Studies: Replace bleeding time; identify specific functional defects (e.g., absent ristocetin response in Bernard-Soulier).
• Specific Factor Assays: Quantify functional activity of individual coagulation proteins.
• Von Willebrand Panel: Includes von Willebrand antigen, ristocetin cofactor activity, factor VIII assay.

Management Strategies

Platelet Disorder Interventions

• Immune Thrombocytopenia: Corticosteroids, intravenous immunoglobulin (IVIG).
• Chronic Refractory Disease: Thrombopoietin receptor agonists (eltrombopag, romiplostim).
• Severe Hemorrhage: Platelet transfusions reserved for life-threatening bleeds.
• Functional Defects: Desmopressin (DDAVP) enhances hemostasis in certain storage pool deficiencies.

Coagulation Disorder Interventions

• Factor Replacement: Specific recombinant or plasma-derived concentrates (Factor VIII, Factor IX) for hemophilia.
• Fresh Frozen Plasma (FFP): Replaces multiple factors; treats liver disease coagulopathy or rare factor deficiencies (e.g., Factor V).
• Cryoprecipitate: Concentrated source of fibrinogen, factor VIII, factor XIII, von Willebrand factor.
• Antifibrinolytic Agents: Aminocaproic acid or tranexamic acid controls mucosal hemorrhage.
• Vitamin K: Corrects deficiency-associated coagulopathy.