Certified Phlebotomy Technician Exam Trivia 4 — Questions and Answers
Question 1: What is the purpose of inverting a blood collection tube after draw?
- To remove air bubbles
- To mix the blood with the additive (Correct answer)
- To prevent hemolysis
- To label the tube properly
Correct answer: To mix the blood with the additive
Inverting the tube mixes the blood with the additive (anticoagulant or clot activator) to ensure proper specimen integrity.
Question 2: Which artery is most commonly used for arterial blood gas (ABG) collection?
- Brachial artery
- Femoral artery
- Radial artery (Correct answer)
- Ulnar artery
Correct answer: Radial artery
The radial artery at the wrist is preferred for ABG collection because it is accessible, has good collateral circulation, and is easy to compress after the draw.
Question 3: What does a positive Allen test result indicate before radial artery puncture?
- The radial artery is blocked
- Adequate collateral circulation exists from the ulnar artery (Correct answer)
- The patient has poor venous access
- Anticoagulant therapy is present
Correct answer: Adequate collateral circulation exists from the ulnar artery
A positive Allen test confirms adequate ulnar artery collateral flow, meaning the hand will remain perfused even if the radial artery is damaged.
Question 4: Which tube is used to collect a specimen for a fasting blood glucose test?
- Light blue top
- Gray top (sodium fluoride) (Correct answer)
- Green top
- Red top
Correct answer: Gray top (sodium fluoride)
The gray top tube contains sodium fluoride, a glycolytic inhibitor that prevents red blood cells from consuming glucose and preserves the sample accurately.
Question 5: What is the recommended angle of needle insertion for a routine venipuncture?
- 5–10 degrees
- 15–30 degrees (Correct answer)
- 45–60 degrees
- 90 degrees
Correct answer: 15–30 degrees
A 15–30 degree angle optimizes vein entry while minimizing the risk of passing through the vein or causing excessive trauma.
Question 6: Which of the following is a contraindication for drawing blood from a specific arm site?
- The patient is right-handed
- The site has an AV fistula for dialysis (Correct answer)
- The patient has tattoos on the arm
- The vein is visible without palpation
Correct answer: The site has an AV fistula for dialysis
Drawing from an arm with an AV fistula risks damaging the fistula, introducing infection, and producing inaccurate results due to altered hemodynamics.
Question 7: What is 'reflux' in phlebotomy and why is it dangerous?
- Blood flowing backward into the patient's vein from a tube additive (Correct answer)
- Overflow of blood from a puncture site
- Hemolysis caused by rapid draw speed
- Air entering the vein through the needle
Correct answer: Blood flowing backward into the patient's vein from a tube additive
Reflux occurs when additive-contaminated blood flows back from the tube into the patient's vein, which can cause adverse reactions including cardiac events from potassium additives.
Certified Phlebotomy Technician Exam Trivia 4
What is the purpose of inverting a blood collection tube after draw?