Certified Phlebotomy Technician Exam General 4 — Questions and Answers
Question 1: A gray-top tube contains sodium fluoride. Its PRIMARY purpose is to:
- Prevent platelet aggregation
- Preserve glucose by inhibiting glycolysis (Correct answer)
- Accelerate clot formation
- Bind calcium for coagulation testing
Correct answer: Preserve glucose by inhibiting glycolysis
Sodium fluoride inhibits the enzyme enolase, halting glycolysis and stabilizing glucose levels in the specimen.
Question 2: Which standard precaution applies to ALL patients regardless of known infection status?
- Wearing a full face shield for every draw
- Treating all blood and body fluids as potentially infectious (Correct answer)
- Double-gloving on every venipuncture
- Using contact precautions in every room
Correct answer: Treating all blood and body fluids as potentially infectious
Standard precautions require treating every patient's blood and body fluids as infectious to protect both patient and healthcare worker.
Question 3: A 2:1 blood-to-additive ratio error in a sodium citrate tube most commonly causes:
- Falsely prolonged PT/aPTT results (Correct answer)
- Hemolysis of red cells
- Falsely elevated potassium
- Clot formation in the tube
Correct answer: Falsely prolonged PT/aPTT results
Underfilling a citrate tube leaves excess anticoagulant, which falsely prolongs clotting times by over-chelating calcium.
Question 4: The antecubital fossa is located:
- On the back of the hand
- In the inner bend of the elbow (Correct answer)
- On the inner surface of the wrist
- On the lateral forearm near the thumb
Correct answer: In the inner bend of the elbow
The antecubital fossa is the triangular depression at the front of the elbow, where the major veins used for venipuncture are found.
Question 5: Which organization publishes the H3 and H4 guidelines used for phlebotomy procedures?
- CDC
- OSHA
- CLSI (Correct answer)
- CAP
Correct answer: CLSI
The Clinical and Laboratory Standards Institute (CLSI) publishes procedure standards including H3 for venipuncture and H4 for skin puncture.
Question 6: When performing a heel stick on a newborn, the puncture should be made on the:
- Posterior curvature of the heel
- Plantar surface of the great toe
- Medial or lateral plantar surface of the heel (Correct answer)
- Dorsal surface of the foot
Correct answer: Medial or lateral plantar surface of the heel
CLSI guidelines specify the medial or lateral plantar surface of the heel to avoid the calcaneus bone and posterior curved area.
Question 7: A patient has a mastectomy on her left side. Where should the phlebotomist draw blood?
- Left arm antecubital only
- Either arm with double tourniquet
- Right arm or non-affected extremity (Correct answer)
- Hand veins on the left side only
Correct answer: Right arm or non-affected extremity
Drawing from the same side as a mastectomy risks lymphedema and unreliable results due to compromised lymphatic drainage.
Certified Phlebotomy Technician Exam General 4
A gray-top tube contains sodium fluoride.
Its PRIMARY purpose is to: