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Chapter 2. Hematology

What is the first step in hemostasis?

A. Platelet aggregation

B. Vascular vasodilation

C. Vascular vasoconstriction

D. Fibrin formation

Answer: C. When there is disruption at the endothelium causing bleeding, the first step in hemostasis is vasoconstriction followed by the adherence of platelets to the injured site by the link of glycoprotein receptor 1b (platelet surface) to the vessel wall by circulation vWF. This expresses the surface receptor glycoprotein IIb/IIIa on the platelet. Platelets aggregate, forming a platelet plug, and this is followed ultimately by fibrin formation.

What is the most common congenital hypercoagulability disorder?

A. Prothrombin gene defect G20210 A

B. Protein C deficiency

C. Protein S deficiency

D. Factor V Leiden

Answer: D. Factor V Leiden (resistance to activated protein C) is reportedly present in 20% to 60% of cases of venous thrombosis. It is present in 1% to 2% of the population. Compared to other hypercoagulable disorders, it is of lower risk in forming thrombus and more likely the thrombus will be venous rather than arterial.

What blood product listed does not carry the risk of HIV and hepatitis B or C?

A. Whole blood

B. Albumin

C. Platelets

D. Fresh frozen plasma

Answer: B. Albumin carries the theoretical risk of Creutzfeldt-Jakob disease.

What drug can be used to treat bleeding with transurethral prostate resection?

A. Hirudin

B. Ancrod

C. Aminocaproic acid

D. Urokinase

Answer: C. Aminocaproic acid is a lysine analogue that inhibits fibrinolysis. It competitively binds to the lysine-binding sites of a fibrin clot, blocking the binding of plasminogen.

A 45-year-old male with the diagnosis of antithrombin III deficiency develops a DVT. What do you have to administer to the patient prior to starting heparin?

A. Cryoprecipitate

B. Platelets

C. Fresh frozen plasma



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