What is the primary use of EDTA tubes in clinical pathology?

• A. CBC and peripheral blood smear evaluation
• B. Plasma chemistry testing
• C. Plasma glucose testing
• D. Urine analysis

Answer: (A)

EDTA tubes are used primarily for complete blood count and peripheral blood smear evaluation because EDTA acts as an anticoagulant by chelating calcium, which stops clotting and keeps blood cells in suspension. This preserves cell morphology, size, and the relative numbers of red cells, white cells, and platelets, which is essential for accurate automated counts and careful smear review. Tests that rely on plasma chemistry or glucose measurement use different additives (such as heparin or fluoride/oxalate) because EDTA can interfere with enzymatic assays or glucose stability. Urine analysis uses a separate collection method as well. So, the main reason EDTA tubes are favored in hematology is to prevent clotting while preserving cellular structure for reliable CBC results and smear interpretation.