For accurate results of blood tests, many things depend on the order of pull the sampler uses or order of draw phlebotomy . This is a specific order that must be used to avoid contamination and imprecise results. A chart detailing this order should be displayed in each bleeding room so that even if a sampler forgets, she can immediately consult the chart and correctly draw the specimens. The fact is that there are a lot of different tubes that can be used while drawing blood. The identification of each tube can be made by knowing the additives placed in the tubes and also with the color of the stopper. Looking at their color one can identify each tube on the stopper, and they carry different additives in them. The different additives cause specific differences, and hence the blood is treated in each of those different tubes differently. They should be written in the order below if you are using a vacuum tube system:
- Sterile Tubes
- Coagulation Tubes
- Serum Tubes
- Plasma Separation Tubes or Heparin
- Glycolytic Inhibitor or Oxalate Tubes and EDTA Tubes
Sterile tubes have caps of pale yellow, and they are larger compared to the tubes of blood collection used usually. The tubes used for coagulation have caps of light blue color. Tubes used for serum can be of a red cap, having or not having activator for clots at the bottom of the tube, the plastic cap of bright yellow or they may be having red and gray spotted rubber stoppers. Plasma separation and Heparin tubes come in the color of green and gray or light green. Tubes of lavender caps use EDTA. Gray tubes overcome are tubes or inhibitors of oxalate glycolysis.
It is essential that this drawing order in each blood draw is followed. Sterile tube if established after tube, you lose sterility and so the risk of contaminating this specimen. If pulled from the order, EDTA may still be present as a trace on the needle and may keep the next tube from clotting the way it is supposed to do. You do not want to introduce heparin, an anticoagulant, a coagulation tube because that skew your results.
It is a modification of the order at times to shoot when the sampler uses a system of the syringe. Because the blood immediately begins to clot at the entrance of the syringe, this is preferred in some institutions, if immediately a syringe is used after tubes that are sterile and the tubes of EDTA are being filled, the tubes filled last where coagulation is needed. Whichever draw order is used in the facility, all the tubes needs to be filled fast after a draw of the syringe to avoid problems.
At times, in performing phlebotomy, the process of fingertip technique is used. The order of drawing is different from the one used in the regular venous process. During a fingertip, immediately the skin perforation begins the process of coagulation, so the EDTA or lavender tubes need to be filled quickly and accurately, then the tubes that contain additives are filled, the formation of clot tubes are kept to be filled for the last.
Vacuum tube manufacturers usually have detailed maps full of colors available to show the correct drawing order. Keep them in the best place to prevent errors.