Try 5 free practice questions with instant feedback. See how ready you are.
Question 1
What is the correct order of draw for venipuncture using evacuated tubes?
Answer: Blood cultures, light blue (sodium citrate), red/gold (SST), green (heparin), lavender (EDTA), gray (sodium fluoride/potassium oxalate).
Question 2
Which additive is found in a lavender/purple-top tube, and what is its primary use?
Answer: EDTA (ethylenediaminetetraacetic acid); it is used for complete blood count (CBC) and hematology studies by preventing clotting through calcium chelation.
Question 3
What does a gray-top tube contain, and why is it used for glucose testing?
Answer: It contains sodium fluoride (a glycolytic inhibitor) and potassium oxalate (anticoagulant); sodium fluoride prevents cells from consuming glucose, preserving accurate glucose levels.
Question 4
What is the maximum angle at which a needle should be inserted during venipuncture?
Answer: 15 to 30 degrees, bevel up, in the direction of blood flow.
Question 5
What is hemoconcentration, and what causes it during venipuncture?
Answer: Hemoconcentration is an increased concentration of larger molecules in the blood; it is caused by leaving the tourniquet on for more than one minute, which increases falsely elevated results.