VERIFIED ANSWERS AND DETAILED RATIONALE
1. Lavender-topped tube contains which additive?
A. No additive
B. SPS
C. Sodium citrate
D. EDTA
Correct Answer: D. EDTA
EDTA (ethylenediaminetetraacetic acid) is the anticoagulant found in
lavender-topped tubes. It works by binding calcium ions, preventing
blood from clotting. These tubes are used primarily for hematology
studies, including complete blood counts (CBC).
2. Which additive is found in a gray-topped tube?
A. Sodium citrate
B. EDTA
C. Potassium oxalate
D. Heparin
Correct Answer: C. Potassium oxalate
Gray-topped tubes contain potassium oxalate as an anticoagulant and
sodium fluoride as a preservative. The potassium oxalate prevents
,clotting by removing calcium, while sodium fluoride inhibits glycolysis,
preserving glucose levels for up to 24 hours.
3. Which needle has the largest gauge?
A. 25 gauge
B. 21 gauge
C. 20 gauge
D. 16 gauge
Correct Answer: D. 16 gauge
Needle gauge numbers work inversely - the smaller the number, the
larger the diameter. A 16-gauge needle has the largest lumen, making it
suitable for rapid blood collection or transfusion procedures where high
flow rates are needed.
4. What gauge needle is typically used for routine adult venipuncture?
A. 23 gauge
B. 25 gauge
C. 16 gauge
D. 21 gauge
Correct Answer: D. 21 gauge
The 21-gauge needle is the standard choice for adult venipuncture. It
provides an optimal balance between patient comfort and adequate
blood flow. It allows for efficient collection while minimizing hemolysis
and patient discomfort.
,5. Which venipuncture equipment consists of a needle attached to
plastic tubing?
A. Syringe
B. Micro-collection container
C. Evacuated tube system
D. Winged infusion set
Correct Answer: D. Winged infusion set
A winged infusion set (commonly called a butterfly) features a short
needle with plastic "wings" for stability, attached to flexible tubing. This
design provides greater maneuverability and is ideal for accessing small
or fragile veins.
6. Which statement about winged infusion sets is NOT true?
A. Commonly referred to as butterfly
B. Comes in needle sizes of 16g and 18g
C. Used on fragile veins
D. Preferred over a syringe
Correct Answer: B. Comes in needle sizes of 16g and 18g
Winged infusion sets typically come in smaller gauge sizes, usually 21-
25 gauge. They do not come in 16g or 18g sizes, which are too large for
the delicate veins these devices are designed to access.
7. A patient took medications with orange juice before a fasting blood
glucose test. What should the phlebotomist do?
A. Draw the blood anyway
, B. Explain you cannot draw without physician consult
C. Tell patient to call physician immediately
D. Ask patient to return tomorrow
Correct Answer: B. Explain you cannot draw without physician consult
When a patient has not properly fasted (consumed orange juice which
contains sugar), the blood glucose results would be invalid. The
phlebotomist should explain the situation and consult with the
physician to determine if the test should be rescheduled or if the
physician wants the test performed anyway.
8. Which action is INCORRECT during dermal puncture?
A. Using a 2.0 mm lancet on a child
B. Puncturing the plantar heel surface
C. Allowing alcohol to dry before puncture
D. Collecting the first drop of blood
Correct Answer: D. Collecting the first drop of blood
The first drop of blood from a dermal puncture should be wiped away
because it may contain tissue fluid, alcohol residue, or other
contaminants that can dilute the sample and affect test results.
Subsequent drops should be collected.
9. What is the primary function of veins?
A. Carry oxygen-rich blood to the heart
B. Facilitate oxygen exchange