What is the correct order for drawing blood samples from multiple tubes?

The correct order for drawing blood samples from multiple tubes is important to avoid cross-contamination of additives in the tubes and to ensure accurate test results. The order of draw typically follows the principles established by laboratory standards.

The sequence usually begins with tubes that contain no additives, such as red-top tubes, followed by tubes with additives that perform specific functions, such as anticoagulants or serum separators. In this case, the red tube, which is without additives, is drawn first, helping to minimize contamination risks. Following that, green-top tubes, which contain heparin (an anticoagulant), should be collected next. Afterward, gray-topped tubes, often used for glycolytic inhibitors, are drawn. Lastly, lavender-topped tubes, which contain EDTA (another anticoagulant), should be drawn to prevent any carryover of other additives from previous tubes.

This careful order ensures that the specimen quality is preserved and each analysis conducted will yield valid results, especially for sensitive tests. Therefore, the sequence starting with the red tube and following through green, gray, and ending with lavender aligns with established phlebotomy practices.