As a Phlebotomist, knowledge, and adherence to the Order of Draw are equally important as the skill of venipuncture. The tests ordered by the clinician can only provide useful information if the blood is collected in the correct tubes with the appropriate additives and free from contaminants¹. Studies from as far back as 1977 show evidence of skewed blood chemistry due to suspected contaminants from tube additives². The Clinical and Laboratories Standards Institute (CLSI) has set laboratory guidelines regarding the Order of Draw so that phlebotomists and other healthcare providers can stay up-to-date on techniques and research in an unceasingly evolving field.

Though some recent studies have been mixed on the Order of Draw’s relevance, the current standard of care acknowledges the risk of specimen contamination and emphasizes the importance of the Order of Draw¹. Contamination of blood specimens not only has implications on the validity of lab results but also has repercussions on supply waste, resources, time, and inevitably, the potential of inaccurate patient care if a contaminated specimen is not recognized².

When considering the Order of Draw, deferring to the latest from CLSI and the tube manufacturer should be the foremost consideration. Manufacturers may have subtle differences in their Order of Draw based on specific additive properties; therefore, these must always be reviewed first by any healthcare provider completing a blood draw. Generally, the Phlebotomist should be most familiar with the labeled additives in the tubes they are working with and the potential for cross-contamination between additives rather than simply considering the color of the tube topper. Close attention to the Order of Draw and labeled additives limits inaccuracies and errors during blood specimen collection.

The CLSI recommended that the Order of Draw always begin with any ordered culture specimens. These tubes are the most sensitive to cross-contamination and at the greatest risk of compromise if contamination occurs from skin bacteria, other external bacteria contamination that could occur during the procedure, and chemical contamination risk from other tube additives. The next tube in the collection sequence should contain sodium citrate, an anticoagulant used for certain plasma tests. Specimens with mild anticoagulant additives, like sodium citrate, should be drawn prior to those with clot activators, as the clot activator additives would override this milder anticoagulant additive. Third in succession are serum testing tubes with or without clot activator additives and with or without gel separators. This concludes the most mild additives in the Order of Draw. The additive-containing tubes that follow fall in order of least to most offensive and/or corrosive to specimens if cross-contamination occurs: Heparin, followed by EDTA, then sodium fluoride with potassium oxalate, and lastly, acid citrate dextrose solution (ACD).⁴

Interested in learning more? PhlebCE.com covers this and other topics that are both engaging and medically relevant for practicing phlebotomists who need to expand their knowledge for continued education certification renewal.

References:

1. Bowen, R. A. R., & Remaley, A. T. (2014, February 15). Interferences from blood collection tube components on clinical chemistry assays. Biochemia Medica. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3936985/
2. Bazzano, G., Galazzi, A., Domenico Giusti, G., Panigada, M., & Laquintana, D. (2021, February 7). The Order of Draw during Blood Collection: A Systematic Literature Review. National Library of Medicine. Retrieved December 8, 2023, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7915193/
3. Kronenberger, J., & Ledbetter, J. (2016). Lippincott Williams & Wilkins’ comprehensive medical assisting. Wolters Kluwer.
4. Specimen Collection and Preparation. (n.d.). Mayo Clinic Laboratories. Retrieved December 8, 2023, from http://a1.mayomedicallaboratories.com/webjc/attachments/72/6ce9c43-specimen-collection-and-preparation.pdf