Specimen Processing and Handling Flashcards

What is the maximum time a whole blood specimen should remain at room temperature before centrifugation?

Answer: 60 minutes

Whole blood specimens should be centrifuged within 60 minutes of collection to prevent cellular metabolism from altering analyte levels.

Which additive tube must NEVER be inverted after collection?

Answer: None — all tubes require inversion

All additive tubes require gentle inversion immediately after collection to mix the additive thoroughly with the blood.

A serum specimen appears hemolyzed. Which analyte result is MOST likely to be falsely elevated?

Answer: Potassium

Potassium is highly concentrated inside red blood cells, so hemolysis releases it into the serum, causing falsely elevated potassium values.

When processing a urine culture specimen, the preferred storage condition before transport is:

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.

What does 'aliquoting' a specimen mean in the laboratory context?

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.

Which tube color is used for plasma protein electrophoresis requiring heparin anticoagulant?

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.

A specimen labeled 'STAT' arrives at the lab. According to standard processing guidelines, it should be processed within:

Answer: 30 minutes

STAT specimens should generally be processed and resulted within 30 minutes of receipt to meet critical turnaround time expectations.