Specimen Handling and Processing Flashcards

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

Answer: 2 hours

Most serum specimens should be centrifuged within 2 hours of collection to prevent cellular metabolism from altering analyte values.

Which tube additive can cause falsely elevated potassium results if the specimen is hemolyzed?

Answer: EDTA

EDTA chelates calcium and can cause potassium to leak from red blood cells when hemolysis occurs, falsely elevating potassium levels.

A specimen labeled 'STAT' arrives at the lab at the same time as a routine specimen. Which specimen should be processed first?

Answer: The STAT specimen, as it has higher priority

STAT specimens always take priority over routine specimens because they indicate urgent patient care needs.

What is the purpose of inverting a blood collection tube after collection?

Answer: To mix the additive with blood

Gentle inversion mixes the tube additive (anticoagulant, gel separator, etc.) thoroughly with the blood specimen.

Which specimen storage condition is required for cold agglutinin testing?

Answer: Keep warm at 37°C until testing

Cold agglutinin specimens must be kept warm (37°C) because cold temperatures cause the antibodies to bind and give false results.

How many times should a tube with EDTA be inverted after collection?

Answer: 8–10 times

EDTA tubes should be inverted 8–10 times to ensure adequate mixing of the anticoagulant with blood without causing hemolysis.

What does a gel separator in an SST tube do after centrifugation?

Answer: Forms a barrier between serum and cells

The thixotropic gel migrates during centrifugation to form a stable physical barrier between the serum layer and the clot.