NPS Phlebotomy Practice Exam

Color coding in blood collection tubes signals the additive and the intended tests. Lavender-topped tubes contain EDTA for hematology, but replacing them with pink-stopper tubes standardizes specimens for immunohematology and blood bank work. Both tube types have EDTA to prevent clotting by binding calcium, which preserves cells for accurate testing. The pink color specifically marks EDTA tubes used for blood bank compatibility testing, helping staff distinguish them from CBC/sedimentation tubes and reducing mix-ups. The other colors indicate different additives and uses: blue for coagulation studies with citrate, green for chemistry tests with heparin, and red for serum testing with no anticoagulant (or a clot activator).