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Hematology & Coagulation Flashcards

7 cards from real AACC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. Which coagulation factor is deficient in classic Hemophilia A?

    Answer: Factor VIII

    Hemophilia A is caused by a deficiency of Factor VIII, an essential cofactor in the intrinsic coagulation pathway, resulting in prolonged aPTT.

  2. The prothrombin time (PT) primarily evaluates which coagulation pathway?

    Answer: Extrinsic and common pathways

    PT measures the extrinsic and common pathways (Factors VII, X, V, II, and fibrinogen) and is initiated by tissue factor (thromboplastin) added to the sample.

  3. Which laboratory test is the standard for monitoring unfractionated heparin (UFH) therapy?

    Answer: Activated partial thromboplastin time (aPTT)

    UFH is monitored with aPTT because heparin potentiates antithrombin III inhibition of intrinsic pathway factors, prolonging the aPTT; therapeutic range is typically 1.5–2.5× control.

  4. What is the mechanism of action of warfarin as an anticoagulant?

    Answer: Inhibition of vitamin K–dependent carboxylation of Factors II, VII, IX, and X

    Warfarin inhibits vitamin K epoxide reductase, preventing the recycling of vitamin K needed for carboxylation and activation of Factors II, VII, IX, X, and proteins C and S.

  5. A patient presents with prolonged bleeding time, normal PT, and normal aPTT. Which condition is most likely?

    Answer: Von Willebrand disease or platelet dysfunction

    Isolated prolonged bleeding time with normal PT and aPTT indicates a defect in primary hemostasis, most commonly von Willebrand disease or platelet function disorders.

  6. Which coagulation pathway is initiated by the exposure of tissue factor (thromboplastin) to blood?

    Answer: Extrinsic pathway

    The extrinsic pathway is triggered when tissue factor (released from damaged subendothelial cells) binds Factor VIIa to activate Factor X, initiating coagulation.

  7. What is the role of fibrinogen (Factor I) in secondary hemostasis?

    Answer: Serving as the substrate for thrombin to generate fibrin clot

    Thrombin (Factor IIa) cleaves fibrinogen into fibrin monomers that polymerize into a mesh; Factor XIIIa then cross-links the fibrin polymers to stabilize the clot.