NAPTP Specimen Processing and Handling 1 — Questions and Answers
Question 1: What is the maximum time a whole blood specimen should sit before being centrifuged if serum is required?
- 15 minutes
- 30 minutes
- 60 minutes (Correct answer)
- 2 hours
Correct answer: 60 minutes
Whole blood specimens should be allowed to clot for 30–60 minutes before centrifugation; exceeding 2 hours can compromise analyte integrity, but 60 minutes is the standard upper threshold.
Question 2: Which additive tube must NEVER be centrifuged?
- SST (gold)
- EDTA (lavender) (Correct answer)
- Lithium heparin (green)
- Sodium citrate (light blue)
Correct answer: EDTA (lavender)
EDTA tubes are collected for whole blood analysis (CBC); centrifuging them separates plasma, destroying the specimen's intended use.
Question 3: A specimen labeled 'STAT' should be processed within how many minutes of collection?
- 15 minutes (Correct answer)
- 30 minutes
- 45 minutes
- 60 minutes
Correct answer: 15 minutes
STAT specimens require processing within 15 minutes of collection to ensure rapid, accurate results for urgent clinical decisions.
Question 4: When transporting a cold-sensitive specimen, which method is most appropriate?
- Place in a heat block at 37°C
- Transport in ice slurry at 0–4°C (Correct answer)
- Keep at room temperature in a sealed bag
- Freeze immediately at -20°C
Correct answer: Transport in ice slurry at 0–4°C
Cold-sensitive specimens such as ammonia, lactic acid, or ABGs must be transported in an ice slurry (0–4°C) to slow metabolic degradation.
Question 5: Which of the following causes hemolysis in a blood specimen?
- Inverting the tube gently 8 times
- Allowing adequate clotting time
- Forcing blood through a small-gauge needle rapidly (Correct answer)
- Labeling the tube before collection
Correct answer: Forcing blood through a small-gauge needle rapidly
Forcing blood through a small-gauge needle or syringe at high velocity creates shear stress that ruptures red blood cells, causing hemolysis.
Question 6: What does a hemolyzed specimen indicate when visually inspected?
- Clear, pale yellow serum or plasma
- Pink to red discoloration of serum or plasma (Correct answer)
- Dark brown discoloration
- Milky white turbid appearance
Correct answer: Pink to red discoloration of serum or plasma
Hemolysis releases hemoglobin from red blood cells into the serum or plasma, producing a characteristic pink to red color.
Question 7: A lipemic specimen appears:
- Clear and colorless
- Pink or red
- Dark brown
- Milky or cloudy white (Correct answer)
Correct answer: Milky or cloudy white
Lipemia is caused by elevated triglycerides in the blood, giving serum or plasma a milky, turbid, or cloudy white appearance.
NAPTP Specimen Processing and Handling 1
What is the maximum time a whole blood specimen should sit before being centrifuged if serum is required?