NHA Certified Phlebotomy Technician (CPT)Specimen HandlingMedium
A phlebotomy technician is preparing to process a potassium specimen collected in a lavender-top (EDTA) tube. Which of the following actions should the technician take?
- ACentrifuge the specimen immediately after collection.
- BMix the tube by inverting it 8-10 times.
- CPour the specimen into a red-top tube for processing.
- DAllow the specimen to clot for 30 minutes.
Show answer & explanationAnswer & explanation
Correct answer: B. Mix the tube by inverting it 8-10 times.
Lavender-top tubes contain EDTA, an anticoagulant that prevents clotting. They require gentle inversion 8-10 times to ensure proper mixing of the additive with the blood, which is essential for accurate CBC and other hematology tests.
Why the other options are wrong
- A. Immediate centrifugation without proper mixing of EDTA can lead to incomplete anticoagulation and specimen issues.
- C. Transferring a specimen from one tube to another without a specific medical reason is poor practice and can lead to contamination, mislabeling, or dilution errors. Also, a red-top tube is for serum, not anticoagulated whole blood.
- D. EDTA tubes are anticoagulated and should not be allowed to clot; this action is for serum tubes.
EDTA Tube Mixing
EDTA (ethylenediaminetetraacetic acid) tubes prevent blood from clotting by binding calcium. Proper mixing via gentle inversion is essential immediately after collection to ensure the anticoagulant is evenly distributed throughout the blood specimen.
- Contains EDTA anticoagulant.
- Used for hematology (CBC) and blood bank tests.
- Requires 8-10 gentle inversions immediately after collection.
- Prevents microclots and inaccurate results.
Memory trick: Mix it right, keep blood from clot's plight.