Phlebotomy Test Specimen Processing and Handling 2 — Questions and Answers
Question 1: What is the maximum time a whole blood specimen should remain at room temperature before centrifugation?
- 15 minutes
- 30 minutes
- 60 minutes (Correct answer)
- 2 hours
Correct answer: 60 minutes
Whole blood specimens should be centrifuged within 60 minutes of collection to prevent cellular metabolism from altering analyte levels.
Question 2: Which additive tube must NEVER be inverted after collection?
- EDTA (lavender)
- Sodium citrate (light blue)
- Red/gold serum separator
- None — all tubes require inversion (Correct answer)
Correct answer: None — all tubes require inversion
All additive tubes require gentle inversion immediately after collection to mix the additive thoroughly with the blood.
Question 3: A serum specimen appears hemolyzed. Which analyte result is MOST likely to be falsely elevated?
- Sodium
- Potassium (Correct answer)
- Calcium
- Glucose
Correct answer: Potassium
Potassium is highly concentrated inside red blood cells, so hemolysis releases it into the serum, causing falsely elevated potassium values.
Question 4: When processing a urine culture specimen, the preferred storage condition before transport is:
- Room temperature up to 24 hours
- Refrigeration at 2–8°C up to 24 hours (Correct answer)
- Frozen at −20°C
- 37°C incubator to preserve organisms
Correct answer: Refrigeration at 2–8°C up to 24 hours
Urine for culture should be refrigerated at 2–8°C if not processed within 30 minutes to prevent bacterial overgrowth that would skew colony counts.
Question 5: What does 'aliquoting' a specimen mean in the laboratory context?
- Discarding the primary tube after testing
- Dividing the specimen into smaller portions for separate tests or storage (Correct answer)
- Centrifuging the specimen twice
- Labeling a specimen with a secondary barcode
Correct answer: Dividing the specimen into smaller portions for separate tests or storage
Aliquoting is the process of dividing a primary specimen into smaller sub-samples so multiple departments can test the same collection without re-drawing the patient.
Question 6: Which tube color is used for plasma protein electrophoresis requiring heparin anticoagulant?
- Light blue (sodium citrate)
- Green (lithium or sodium heparin) (Correct answer)
- Lavender (EDTA)
- Gray (potassium oxalate/sodium fluoride)
Correct answer: Green (lithium or sodium heparin)
Green-top tubes contain heparin anticoagulant and are used for plasma specimens including some chemistry and special tests requiring heparinized plasma.
Question 7: A specimen labeled 'STAT' arrives at the lab. According to standard processing guidelines, it should be processed within:
- 5 minutes
- 15 minutes
- 30 minutes (Correct answer)
- 60 minutes
Correct answer: 30 minutes
STAT specimens should generally be processed and resulted within 30 minutes of receipt to meet critical turnaround time expectations.
Phlebotomy Test Specimen Processing and Handling 2
What is the maximum time a whole blood specimen should remain at room temperature before centrifugation?