ASPT Specimen Collection Techniques 4 — Questions and Answers
Question 1: A phlebotomist is asked to draw a specimen for a fasting glucose test. The patient says they had coffee with sugar 30 minutes ago. The correct action is to:
- Draw the specimen and note it on the requisition
- Draw the specimen — coffee doesn't count as food
- Reschedule the draw after a sufficient fasting period (Correct answer)
- Draw the specimen and discard the first tube
Correct answer: Reschedule the draw after a sufficient fasting period
Sugary coffee breaks the fast and will elevate glucose results; the draw should be rescheduled after the required fasting period.
Question 2: Which specimen type is collected in a green-top tube containing lithium heparin?
- Serum
- Whole blood for CBC
- Plasma for chemistry tests (Correct answer)
- Whole blood for blood cultures
Correct answer: Plasma for chemistry tests
Lithium heparin green-top tubes are used to collect plasma for stat chemistry panels and other plasma-based assays.
Question 3: What is the correct lancet depth for an adult fingerstick to obtain an adequate sample while minimizing pain?
- 0.5 mm
- 1.0 mm
- 2.0 mm (Correct answer)
- 3.0 mm
Correct answer: 2.0 mm
A 2.0 mm depth is standard for adult fingerstick lancets, providing enough blood flow without excessive discomfort or tissue damage.
Question 4: When a patient has an IV line in the arm, blood should ideally be drawn from:
- The same arm, below the IV site
- The same arm, above the IV site
- The opposite arm (Correct answer)
- The IV catheter itself with physician order
Correct answer: The opposite arm
Drawing from the opposite arm avoids IV fluid contamination of the specimen; if unavoidable, draw below the IV with the IV shut off for at least 2 minutes.
Question 5: Which of the following BEST describes the purpose of the order of draw?
- To fill tubes in the order easiest for the phlebotomist
- To prevent additive carryover between tubes that could alter test results (Correct answer)
- To ensure blood cultures are always drawn last
- To allow anticoagulants to activate before serum tubes
Correct answer: To prevent additive carryover between tubes that could alter test results
The order of draw minimizes the risk of additive cross-contamination between tubes that could falsely alter coagulation, chemistry, or hematology results.
Question 6: Which of the following actions can CAUSE hemolysis during specimen collection?
- Using a 21-gauge needle
- Gently inverting tubes 5–8 times
- Vigorously shaking the tube after collection (Correct answer)
- Applying a tourniquet for 45 seconds
Correct answer: Vigorously shaking the tube after collection
Vigorous shaking mechanically lyses red blood cells, causing hemolysis that interferes with potassium, LDH, and other analytes.
Question 7: A STAT specimen for electrolytes arrives in the lab in a serum separator tube (SST). The tube has not been centrifuged. The correct next step is to:
- Run the test directly on the whole blood in the tube
- Centrifuge immediately and analyze the serum (Correct answer)
- Refrigerate until the next scheduled centrifuge run
- Discard and recollect in a green-top tube
Correct answer: Centrifuge immediately and analyze the serum
SST tubes must be centrifuged to separate serum from cells before analysis; STAT orders require immediate centrifugation.
ASPT Specimen Collection Techniques 4
A phlebotomist is asked to draw a specimen for a fasting glucose test.
The patient says they had coffee with sugar 30 minutes ago.
The correct action is to: