Final answer:
The proper order of draw for blood collection is to start with blood cultures, followed by citrated tubes, serum tubes, heparin tubes, EDTA tubes, and glycolytic inhibitor tubes. This sequence prevents cross-contamination and ensures the accuracy of laboratory tests.
Step-by-step explanation:
The proper order of draw when collecting multiple tubes of blood is crucial to prevent cross-contamination of additives between tubes. The general order recommended by the Clinical and Laboratory Standards Institute (CLSI) is as follows:
- Blood cultures
- Citrated tubes (light blue top)
- Serum tubes with or without clot activator or gel (red top or gold top serum separator tubes)
- Heparin tubes with or without gel plasma separator (green top)
- EDTA tubes (lavender or pink top)
- Glycolytic inhibitor tubes (gray top)
Each type of tube contains different additives that prevent blood from clotting or preserve certain components of the blood, and they need to be filled in the correct sequence to ensure accurate test results. For example, EDTA tubes are commonly used to obtain plasma by centrifugation and are essential for complete blood count tests, while heparin tubes prevent clotting and are used to measure electrolytes and other blood gases.
When blood samples are collected into tubes containing K2EDTA, for instance, this helps preserve the blood cells and prevent clotting, which is critical for certain plasma-based tests.