National Certified Phlebotomy Technician MCQ Flashcards

A complete blood count (CBC) specimen must be collected in which tube?

Answer: Lavender/purple (EDTA)

CBC specimens are collected in lavender/purple EDTA tubes because EDTA best preserves blood cell morphology and prevents platelet clumping.

Which of the following is an example of a timed specimen that must be drawn at a specific time?

Answer: Peak drug level (e.g., vancomycin)

Peak drug levels must be drawn at a specific time after medication administration to measure the highest concentration.

What is the purpose of the buffy coat layer visible after blood centrifugation?

Answer: It is a thin layer of white blood cells and platelets between plasma and red blood cells

The buffy coat is a thin whitish layer between the plasma/serum and the packed red blood cells, consisting of white blood cells and platelets.

Which anticoagulant prevents clotting by inhibiting thrombin through activation of antithrombin III?

Answer: Heparin

Heparin prevents clotting by binding to and activating antithrombin III, which in turn inhibits thrombin and several other coagulation factors.

A specimen for erythrocyte sedimentation rate (ESR) should be collected in which tube?

Answer: Lavender (EDTA) or black (sodium citrate for ESR)

ESR can be performed on blood collected in a lavender EDTA tube or a specialized black-top tube containing sodium citrate specifically formulated for sedimentation rate testing.

Which laboratory department performs blood typing, crossmatching, and antibody screening?

Answer: Blood bank (immunohematology/transfusion services)

The blood bank (immunohematology or transfusion services) department performs ABO/Rh typing, antibody screening, crossmatching, and manages blood product inventory.