Which blood tube color is associated with ESR testing?

The color associated with ESR (Erythrocyte Sedimentation Rate) testing is purple, typically indicating that the tube contains an anticoagulant such as EDTA. This type of tube is essential for ESR testing because it prevents the blood from clotting, allowing for accurate measurement of the sedimentation rate of red blood cells in plasma over a specified period of time. The anticoagulant ensures that the cells remain suspended in plasma, providing a clear view of how quickly they settle, which is critical for diagnosing and monitoring various inflammatory and autoimmune conditions. Other color tubes, such as red or green, may contain different additives that are suited for other types of tests, which would not be appropriate for ESR.