NAPTP Specimen Processing and Handling 2 — Questions and Answers
Question 1: Which of the following is a pre-analytical error that affects specimen quality?
- Incorrect reagent calibration in the lab
- Using expired analyzer reagents
- Collecting a specimen from an IV line without proper protocol (Correct answer)
- Entering results in the wrong patient record
Correct answer: Collecting a specimen from an IV line without proper protocol
Collecting a specimen from an IV line without proper protocol (e.g., not discarding the first few mL) is a pre-analytical error that dilutes the specimen and compromises results.
Question 2: How should aliquots be labeled when dividing a specimen into multiple tubes?
- Only the original tube needs a label
- Each aliquot must be labeled with the same patient information as the original (Correct answer)
- Aliquots are labeled with a sequential number only
- Aliquots are labeled by the receiving department
Correct answer: Each aliquot must be labeled with the same patient information as the original
Each aliquot must carry the same complete patient identification as the primary specimen to ensure traceability and prevent mix-ups.
Question 3: The recommended centrifuge speed for most routine serum or plasma separations is:
- 500 × g for 15 minutes
- 1,000–2,000 × g for 10 minutes (Correct answer)
- 3,000–4,000 × g for 5 minutes
- 10,000 × g for 1 minute
Correct answer: 1,000–2,000 × g for 10 minutes
Most routine specimens are centrifuged at 1,000–2,000 × g for 10 minutes to achieve adequate separation without damaging cellular components.
Question 4: Which specimen requires protection from light during transport and processing?
- Basic metabolic panel
- Bilirubin (Correct answer)
- PT/INR
- Glucose
Correct answer: Bilirubin
Bilirubin is photosensitive and degrades rapidly when exposed to light; specimens must be wrapped in foil or placed in an amber container.
Question 5: What is the purpose of a separator gel in SST or PST tubes?
- To prevent clotting of the specimen
- To act as a physical barrier between cells and serum/plasma after centrifugation (Correct answer)
- To add anticoagulant to the blood
- To preserve RNA for molecular testing
Correct answer: To act as a physical barrier between cells and serum/plasma after centrifugation
The separator gel migrates during centrifugation to form a stable barrier between the cellular components and the serum or plasma, facilitating clean separation.
Question 6: When must a phlebotomist reject a specimen and request a redraw?
- If the tube was filled to exactly the correct level
- If the specimen is grossly hemolyzed and the test is affected by hemolysis (Correct answer)
- If the tube was mixed by gentle inversion 8 times
- If the specimen arrived within 30 minutes of collection
Correct answer: If the specimen is grossly hemolyzed and the test is affected by hemolysis
Grossly hemolyzed specimens interfere with many analytes (e.g., potassium, LDH, AST) and must be rejected and redrawn to ensure accurate results.
Question 7: For a urine culture specimen, the appropriate container is:
- A red-top evacuated tube
- A sterile urine cup with a tight-fitting lid (Correct answer)
- A gray-top tube with sodium fluoride
- A standard non-sterile plastic cup
Correct answer: A sterile urine cup with a tight-fitting lid
Urine cultures require a sterile container to prevent environmental contamination that could produce false-positive growth results.
NAPTP Specimen Processing and Handling 2
Which of the following is a pre-analytical error that affects specimen quality?