NHA Certified Phlebotomy Technician (CPT)Specimen HandlingMedium
A phlebotomy technician is processing a specimen for a routine complete blood count (CBC). Which of the following actions is critical to prevent pre-analytical error?
- ACentrifuge the specimen immediately after collection to separate plasma.
- BAllow the tube to clot for 30 minutes at room temperature before mixing.
- CGently invert the lavender-top tube 8-10 times immediately after collection.
- DStore the specimen at 37°C until it can be transported to the lab.
Show answer & explanationAnswer & explanation
Correct answer: C. Gently invert the lavender-top tube 8-10 times immediately after collection.
CBC specimens are collected in lavender-top (EDTA) tubes, which are anticoagulated. Gentle inversion immediately after collection ensures proper mixing of the anticoagulant with the blood, preventing microclot formation and ensuring accurate cell counts. Centrifugation, clotting, or warming are inappropriate for a CBC.
Why the other options are wrong
- A. CBCs use whole blood; centrifuging would separate cells from plasma, making it unsuitable for a CBC.
- B. Lavender-top tubes contain an anticoagulant and should *not* be allowed to clot. This would render the specimen unusable for CBC.
- D. Storing a CBC at 37°C would accelerate cellular metabolism and degradation, affecting cell morphology and stability.
CBC Specimen Processing
For a complete blood count (CBC), the lavender-top (EDTA) tube must be gently inverted 8-10 times immediately after collection to ensure proper mixing of the anticoagulant and prevent clotting, preserving the whole blood for analysis.
- EDTA tube (lavender top).
- Gently invert 8-10 times.
- Do not centrifuge or allow to clot.
Memory trick: CBC: Invert Gently, Keep Cells United.