Phlebotomy Practice Test

Phlebotomy Routine Blood Collections Practice Questions

Routine Blood Collections makes up 14 of every 50 questions on a Tigertest Phlebotomy practice test. Here are 10 of the 56 questions on it, each with the answer and the reason.

Updated 2026-11-10 by the Tigertest team. Weighted to the NHA CPT test plan. Order of draw and technique follow CLSI GP41 and GP42.

1. 1. A phlebotomist is drawing a basic metabolic panel from an adult with large, easily palpated antecubital veins. Which needle gauge is standard?

   • A.18 gauge
   • B.21 gauge
   • C.16 gauge
   • D.25 gauge

   Answer: B. A 21-gauge needle, 1 to 1.5 inches long, is the standard for routine adult venipuncture. A 16 gauge is used for blood donation, and a 25 gauge is so narrow that it can hemolyze the specimen.

2. 2. A phlebotomist must draw blood from a 6-year-old with small antecubital veins. Which needle gauge is most appropriate?

   • A.18 gauge
   • B.16 gauge
   • C.20 gauge
   • D.22 gauge

   Answer: D. A 22-gauge needle suits small or pediatric veins, and a 23-gauge winged set can be used for very small veins. The 18 and 20 gauge needles have larger bores than standard and are too big for a small child's veins.

3. 3. Which statement correctly describes how needle gauge numbers work?

   • A.A larger gauge number means a smaller bore
   • B.Gauge describes the angle of the bevel
   • C.A larger gauge number means a larger bore
   • D.Gauge describes the needle length in inches

   Answer: A. Gauge is inversely related to the diameter of the lumen, so a 23 gauge is narrower than a 21 gauge. Needle length is measured separately in inches and has nothing to do with gauge.

4. 4. After a difficult syringe draw, a phlebotomist needs to fill three evacuated tubes. How should the blood be transferred?

   • A.Depress the plunger hard to fill tubes faster
   • B.Push the syringe needle through each stopper
   • C.Use a safety transfer device
   • D.Pour it into open tubes

   Answer: C. A transfer device lets the tube vacuum draw blood in safely without exposing a needle. Pushing the needle through the stopper risks a needlestick, and forcing the plunger hemolyzes cells and can overfill the tube.

5. 5. While setting up, a phlebotomist notices that a lavender tube expired last month. What is the best action?

   • A.Overfill it to make up for lost additive
   • B.Use it if the vacuum seems intact
   • C.Discard it and use an unexpired tube
   • D.Use it only for a small-volume draw

   Answer: C. Expired tubes may have lost vacuum, causing a short draw, and the additive may have degraded, so the specimen can be rejected. A tube that looks fine still cannot be checked for vacuum or additive quality at the bedside.

6. 6. A phlebotomist has finished a venipuncture with a multisample needle and tube holder. What should be done with the holder?

   • A.Discard it with the needle still attached
   • B.Unscrew the needle and reuse the holder
   • C.Disinfect the holder with bleach for reuse
   • D.Keep it for the patient's next scheduled draw

   Answer: A. OSHA requires tube holders to be single use and discarded in the sharps container with the needle attached. Unscrewing the needle exposes its back end and creates a needlestick risk.

7. 7. A patient reports a latex allergy before a routine venipuncture. Which tourniquet should the phlebotomist use?

   • A.The standard latex strap over the sleeve
   • B.A blood pressure cuff inflated to 200 mmHg
   • C.No tourniquet at all for this patient
   • D.A single-use nitrile or vinyl tourniquet

   Answer: D. Latex-free single-use tourniquets avoid an allergic reaction and cross-contamination. A latex strap over the sleeve still risks contact, and a cuff pumped above arterial pressure would stop blood flow instead of distending the vein.

8. 8. What is the purpose of the rubber sleeve over the back end of a multisample needle?

   • A.It controls the vacuum strength inside each tube
   • B.It prevents leaks between tubes
   • C.It locks the needle into the holder
   • D.It keeps the front bevel sterile until insertion

   Answer: B. The sleeve slides back when a tube is pushed on and closes over the needle when the tube is removed, so blood does not leak while tubes are changed. The vacuum is set by the tube itself, not by the sleeve.

9. 9. A provider orders a PT/INR for a patient taking warfarin. Which tube should the phlebotomist collect?

   • A.Green lithium heparin with gel
   • B.Light blue sodium citrate
   • C.Gold serum separator
   • D.Lavender K2 EDTA

   Answer: B. Coagulation tests such as PT/INR and aPTT require sodium citrate, which binds calcium reversibly so the lab can restore it during testing. Heparin is itself an anticoagulant that would interfere with clotting tests.

10. 10. Why must a light blue sodium citrate tube be filled to its fill line?

    • A.To give the clot activator enough blood
    • B.To stop glycolysis before testing
    • C.To ensure the gel barrier forms
    • D.To keep the 9:1 blood-to-citrate ratio

    Answer: D. Coagulation testing depends on a 9:1 ratio of blood to citrate. An underfilled tube has excess citrate that falsely prolongs PT and aPTT, so the lab rejects it; the light blue tube has no gel or clot activator.