July 22, 2022

Phlebotomists, Should You Follow Order of Draw?

Key Takeaways

  • The order of draw is the recommended order for collecting samples and is designed to protect against a tube's additive from carrying over into the next tube and affecting test results.
  • There’s plenty of evidence supporting the need for a specific order in which blood collection tubes should be filled.
  • You should absolutely follow order of draw. The order of draw minimizes cross contamination and ensures test results are as accurate as possible. 
  • Neglecting this key concept can contribute to medical mistakes and potentially lead to misdiagnosis, postponing treatment, or delaying time-sensitive medical decisions.

Are you a phlebotomist, or interested in learning more about phlebotomy? If so, you’ve come to the right place. Getlabs Phlebotomy Tips is a series focused on sharing knowledge, advice, and best practices for phlebotomists and mobile phlebotomists.

Does it matter if you eat dessert before the entree? What about the salad before the soup? Does the order really matter?

The order you eat meals doesn’t really make a difference (except, maybe to the host), but when it comes to phlebotomy and blood draws - the order of draw matters. A lot.

Here’s why you should follow the order of draw, why it’s important, and a brief history of how the order changed over the years.

What is order of draw?

The order of draw is the recommended order for collecting samples and is designed to protect against a tube's additive from carrying over into the next tube and affecting test results. The order is also universal for glass and plastic tubes, and irrespective of whether samples are drawn with a tube holder or syringe. The recommended order is as follows:

  1. Blood culture tubes
  2. Sodium citrate tubes (e.g., blue-stopper)
  3. Serum tubes with or without clot activator, with or without gel separator (e.g., red-,gold-, speckled-stopper)
  4. Heparin tubes with or without gel (e.g., green-stopper)
  5. EDTA tubes (e.g., lavender-stopper)
  6. Glycolytic inhibitor tubes (e.g., gray-stopper)

It’s important to note that some facilities have conducted internal studies that support a variation to the recommended order of draw. When an alternative order is supported by reliable evidence, then the facility’s protocol should be followed.

There’s plenty of evidence supporting the need for a specific order in which blood collection tubes should be filled. In fact, the first evidence was published nearly 30 years ago. Since then, changes have been made based on new evidence and research, with the latest change occurring in 2003.

The change in 2003 was in response to the industry-wide transition from glass blood collection tubes to plastic. The reason behind this shift is because glass is a natural clot activator, whereas plastic is not. Around that time, tube manufacturers changed the composition of blood collection tubes from glass to plastic due to safety reasons. So in order for blood to clot in safer plastic tubes, manufacturers coat the inside of the tube with a substance to facilitate clotting, like silica particles.

Prior to 2003,  it was recommended that the tube following the clot activator tube remained the coag tube. When silica became the clot-activator inside the new plastic tubes, this arrangement threatened the coag results. All major U.S. tube manufacturers came to consensus when the venipuncture standard was revised in 2003: serum tubes that used to precede the blue-stopper coag tube were relocated to follow coag tubes.

Why order of draw is important

Accurate test results rely on accurate samples. When additives carry over into a different tube type, the results may be dramatically affected. Here are a few examples to demonstrate this point:

  • Should the EDTA from a lavender-stopper tube, which is rich in potassium, carry over into a tube to be tested for potassium (a green-, red-, gold-, or speckled-top tube), the level of potassium may be falsely elevated leading to life-threatening mistakes
  • If a clot activator carries over into a tube to be tested for coagulation studies (blue stopper), the prothrombin time (PT) or activated partial thromboplastin time (aPTT) may be falsely shortened
  • When blood cultures are collected at the same time as other lab work and not filled first, bacteria from the non-sterile stoppers of the tubes can contaminate the bottles used for blood cultures

Because we know additives adversely affect test results, we can arrange the tubes and blood culture bottles so that any carryover is irrelevant. This is why the order of draw is so important. Any additive that carries over will have no significant impact on test results.

Should you follow order of draw?

Absolutely. The order of draw is critically important to minimize cross contamination and ensure test results are as accurate as possible. When healthcare professionals with specimen collection responsibilities adhere to the order of draw, patients are more likely to be treated according to results that truly reflect their health status.

Neglecting this key concept can contribute to medical mistakes and potentially lead to misdiagnosis, postponing treatment, or delaying time-sensitive medical decisions.

As always, thanks for stopping by! We look forward to sharing more phlebotomy tips and best practices with you in the future.

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If you’re considering a career as a phlebotomist or curious to learn more, consider working for a mobile phlebotomy service like Getlabs. We hire talented, passionate people from diverse backgrounds, not just because it’s the right thing to do, but because it makes our company stronger as a whole.

If you share our values and our enthusiasm for helping our patients have the best experience, we have a home for you at Getlabs.

Check out our careers page and find out if we’re hiring in your area!

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