ASCP Coagulation 3

Question 1

Which anticoagulant mechanism does antithrombin (AT) primarily use?

Accepted Answer

Serine protease inhibition potentiated by heparin

Answer

Vitamin K antagonism

Answer

Phospholipid binding competition

Answer

Plasminogen activation

Question 2

A mixing study showing 'no correction' (aPTT remains prolonged after mixing with normal plasma) is consistent with:

Accepted Answer

Factor VIII inhibitor

Answer

Factor VIII deficiency

Answer

Factor IX deficiency

Answer

Factor X deficiency

Question 3

Platelet function analyzer (PFA-100) closure time is prolonged in all of the following EXCEPT:

Accepted Answer

Hemophilia A (Factor VIII deficiency)

Answer

von Willebrand disease

Answer

Aspirin therapy

Answer

Thrombocytopenia below 50,000/µL

Question 4

Rivaroxaban (Xarelto) is a direct oral anticoagulant (DOAC) that specifically targets:

Accepted Answer

Factor Xa

Answer

Thrombin (Factor IIa)

Answer

Factor VIIa

Answer

Factor XIa

Question 5

A neonate presents with purpura fulminans and severely low protein C levels. This presentation is caused by:

Accepted Answer

Homozygous or compound heterozygous protein C deficiency

Answer

Heterozygous protein C deficiency

Answer

Factor V Leiden homozygosity

Answer

Acquired protein C deficiency from warfarin

Question 6

In platelet aggregation testing, which reagent tests the thromboxane A2 pathway and is abnormal in aspirin-treated patients?

Accepted Answer

Arachidonic acid

Answer

ADP

Answer

Ristocetin

Answer

Collagen