Phlebotomy Test Blood Collection Equipment and Supplies 1 — Questions and Answers
Question 1: What is the standard needle gauge most commonly used for routine adult venipuncture?
- 18 gauge
- 21 gauge (Correct answer)
- 25 gauge
- 23 gauge
Correct answer: 21 gauge
The 21-gauge needle is the standard for routine adult venipuncture, providing adequate blood flow without causing excessive hemolysis.
Question 2: Which evacuated tube color contains EDTA as its anticoagulant and is most commonly used for CBC testing?
- Light blue
- Green
- Lavender/purple (Correct answer)
- Red
Correct answer: Lavender/purple
Lavender/purple top tubes contain EDTA, which chelates calcium to prevent clotting and is the additive of choice for hematology tests like CBCs.
Question 3: What is the primary purpose of applying a tourniquet during venipuncture?
- To sterilize the puncture site
- To distend veins by restricting venous blood flow (Correct answer)
- To prevent arterial blood from entering the tube
- To reduce patient movement
Correct answer: To distend veins by restricting venous blood flow
A tourniquet restricts venous return, causing veins to distend and become more visible and palpable for easier needle access.
Question 4: What is the maximum recommended time a tourniquet should remain applied during venipuncture?
- 30 seconds
- 2 minutes
- 1 minute (Correct answer)
- 5 minutes
Correct answer: 1 minute
A tourniquet should not remain applied for more than 1 minute because prolonged application causes hemoconcentration, which can falsely elevate cell counts and large-molecule analytes.
Question 5: Which antiseptic is most commonly used to cleanse the venipuncture site for routine blood collection?
- Betadine (povidone-iodine)
- Hydrogen peroxide
- 70% isopropyl alcohol (Correct answer)
- Chlorhexidine gluconate
Correct answer: 70% isopropyl alcohol
70% isopropyl alcohol is the standard antiseptic for routine venipuncture; it must be allowed to air dry completely before needle insertion to prevent hemolysis and inaccurate results.
Question 6: What gauge needle is most commonly used with a butterfly (winged infusion) set for small or fragile hand veins?
- 18 gauge
- 19 gauge
- 21 gauge
- 23 gauge (Correct answer)
Correct answer: 23 gauge
A 23-gauge butterfly needle is preferred for small, fragile, or difficult veins such as hand veins because its smaller diameter causes less trauma to delicate vessels.
Question 7: What is the primary advantage of the evacuated tube (Vacutainer) system over a syringe for routine venipuncture?
- It eliminates the need for a tourniquet
- It allows multiple tube collection from one venipuncture using pre-vacuumed tubes (Correct answer)
- It only requires a 25-gauge needle
- It does not require antiseptic site preparation
Correct answer: It allows multiple tube collection from one venipuncture using pre-vacuumed tubes
The evacuated tube system uses pre-vacuumed tubes that automatically draw the correct blood volume, enabling multiple samples from a single venipuncture by simply changing tubes.
Phlebotomy Test Blood Collection Equipment and Supplies 1
What is the standard needle gauge most commonly used for routine adult venipuncture?