Order of Draw

As a Medical Assistant, knowledge and adherence to the Order of Draw are equally important as the venipuncture skill. 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 is 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 Laboratory Standards Institute (CLSI) has set laboratory guidelines regarding the Order of Draw so that Medical assistantss and other healthcare providers can stay up-to-date on techniques and research in a consistently 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 to patient care 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 the waste of supplies, 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 additives; therefore, these must always be considered first by any healthcare provider completing a blood draw. Generally, the Medical Assistant should be most familiar with the labeled additives in the tubes they are working with and the potential mix of cross-contamination between additives rather than simply considering the color of the tube topper³. Close attention to the Order of Draw and labeled additives limits inaccuracies and errors during blood specimen collection.

Next, we will discuss the recommended Order of Draw. The first tube in the collection should always be the culture collection. These tubes are the most sensitive to cross-contamination and at the greatest risk of compromise if contamination occurs. 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 before those with clot activators, as the clot activator additives would override the anticoagulant additives. 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 fluoride/oxalate, and lastly acid citrate dextrose solution (ACD).⁴

 

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/72/6ce9c4-specimen-collection-and-preparation.pdf