NHA Certified Phlebotomy Technician (CPT)Collection RoutineMedium
A phlebotomy technician is preparing to collect a blood specimen for a complete blood count (CBC). Which of the following tubes should the technician use, and what is its primary additive?
- ALight blue top tube; Sodium Citrate
- BGreen top tube; Heparin
- CLavender top tube; EDTA
- DRed top tube; No additive
Show answer & explanationAnswer & explanation
Correct answer: C. Lavender top tube; EDTA
A complete blood count (CBC) is a hematology test that requires whole blood to prevent clotting while preserving cell morphology. The lavender top tube contains EDTA (ethylenediaminetetraacetic acid), which is the anticoagulant of choice for hematology studies as it binds calcium to prevent clotting without altering cell structure.
Why the other options are wrong
- A. Light blue top tubes (sodium citrate) are for coagulation studies.
- B. Green top tubes (heparin) are for plasma chemistry tests, not typically for CBC as heparin can interfere with some hematology parameters.
- D. Red top tubes (no additive) are for serum chemistry or blood bank, allowing blood to clot.
CBC Tube & Additive
The specific blood collection tube and anticoagulant required for a Complete Blood Count (CBC) test.
- Tube color: Lavender top.
- Additive: EDTA (Ethylenediaminetetraacetic acid).
- Purpose: Prevents clotting while preserving cell morphology for hematology analysis.
Memory trick: CBC and EDTA: Lavender's the Way for Hematology's Play.