Which blood collection tube color is associated with EDTA for hematology testing?

• A. Lithium heparin blood tube
• B. Serum separator tube
• C. Sodium citrate blood tube
• D. EDTA (ethylenediaminetetraacetic acid) blood tube

Answer: (D)

In hematology testing, you need to prevent clotting while preserving the blood cells’ structure for accurate counts and morphology assessment. EDTA works by binding calcium, a mineral required for clot formation, so it stops coagulation and keeps red cells, white cells, and platelets intact. That makes EDTA the go-to anticoagulant for complete blood counts and related tests, and the tube is colored lavender (purple) to indicate its use. By contrast, lithium heparin tubes (green) are used when plasma chemistry is needed, serum separator tubes (red/gold) yield serum after clotting, and sodium citrate tubes (blue) are used for coagulation assays. So the color linked to EDTA for hematology testing is lavender/purple.