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Difficulty: EasyHematology and Oncology

An essential skill in hematology is interpreting coagulation panels to diagnose bleeding disorders. Match each underlying hematologic disorder with its most characteristic laboratory profile.

  • Hemophilia AProlonged aPTT with normal PT, platelet count, and bleeding time
  • von Willebrand diseaseProlonged bleeding time and aPTT with normal PT and platelet count
  • Disseminated intravascular coagulation (DIC)Prolonged PT and aPTT, thrombocytopenia, and decreased fibrinogen
  • Immune thrombocytopenic purpura (ITP)Isolated thrombocytopenia with normal PT and aPTT

Answer

Hemophilia A matches with isolated prolonged aPTT. von Willebrand disease matches with prolonged aPTT and prolonged bleeding time. DIC matches with prolonged PT, aPTT, thrombocytopenia, and decreased fibrinogen. ITP matches with isolated thrombocytopenia.
Each bleeding disorder uniquely disrupts a specific component of the hemostatic system. ITP exclusively destroys platelets (causing isolated thrombocytopenia). Hemophilia A is an isolated Factor VIII deficiency (causing isolated prolonged aPTT). vWD impairs platelet adhesion and Factor VIII stability (causing prolonged bleeding time and aPTT). DIC indiscriminately consumes all coagulation factors and platelets (causing prolonged PT/aPTT, low platelets, and low fibrinogen).

Step-by-Step Solution

1
Evaluate the platelet count and bleeding time to assess primary hemostasis.
Defects in primary hemostasis (ITP, vWD) will show either thrombocytopenia or a prolonged bleeding time.
Primary hemostasis involves the initial formation of the platelet plug at the site of endothelial injury.
2
Evaluate the PT and aPTT to assess secondary hemostasis.
Intrinsic pathway defects (Hemophilia A) prolong aPTT. Deficiencies affecting both pathways or involving massive consumption (DIC) prolong both PT and aPTT.
Secondary hemostasis relies on the coagulation cascade to generate fibrin and stabilize the clot.
3
Combine the lab findings to establish the specific diagnosis.
vWD uniquely affects both primary (platelet adhesion) and secondary (Factor VIII half-life) hemostasis. DIC is broadly consumptive. ITP is strictly limited to platelet destruction. Hemophilia A is strictly limited to Factor VIII.
Identifying the specific combination of coagulation derangements reliably isolates the underlying pathology.

Key Concept

Interpretation of basic coagulation profiles (PT, aPTT, bleeding time, platelet count) to differentiate primary hemostasis defects, secondary hemostasis defects, and consumptive coagulopathies.
Estimated Time:1m 0s
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Topics

Hematology and Oncology

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