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The Crucial Order of Draw in Phlebotomy: Ensuring Accurate Test Results

Within the realm of phlebotomy, the order of draw reigns supreme. It dictates the meticulous sequence in which blood collection tubes are filled during a venipuncture. This seemingly basic concept holds immense significance, as adhering to it safeguards the integrity of test results.

This comprehensive guide delves into the critical role of the order of draw, exploring the potential consequences of disregarding it and providing practical strategies for seamless implementation.

The Cornerstone of Phlebotomy

Key Takeaways
The order of draw is essential in phlebotomy to prevent inaccurate test results. Blood collection tubes contain additives that can interfere with tests in subsequent tubes if not drawn in the correct order.
Disregarding the order of draw can lead to misdiagnosis, delayed treatment, wasted resources, and even life-threatening situations.

The recommended order of draw is:

Blood Culture Tubes

Sodium Citrate Tubes (Blue-Stopper)

Serum Tubes (Red, Gold, Speckled-Stopper)

Heparin Tubes (Green-Stopper)

EDTA Tubes (Lavender-Stopper)

Glycolytic Inhibitor Tubes (Gray-Stopper)

Always prioritize your facility’s established order of draw if it’s based on sound scientific evidence.
Phlebotomists should go beyond memorization and develop a deep understanding of the order of draw and its rationale for effective application.
Following best practices like proper site selection, aseptic technique, and correct tube mixing further ensures high-quality blood draws.

Why Does Order of Draw Matter?

The primary culprit behind the importance of order of draw is additive carryover. Blood collection tubes contain various additives designed to preserve blood components or initiate specific reactions for different tests. If the order of draw is compromised, these additives can inadvertently mix with blood in subsequent tubes, leading to inaccurate test results.

Understanding Additive Carryover

Imagine this scenario: During blood collection, the needle filling a tube might brush against the blood-additive mixture within the preceding tube. This minute amount of carryover can significantly alter test results, potentially leading to misdiagnosis or delayed treatment.

Carryover can occur in both syringe and vacuum blood draws:

  • Syringe Draws: Here, carryover happens through the needle used in the safety transfer device. According to Occupational Safety and Health Administration (OSHA) guidelines, blood collected by syringe should never be transferred directly using the venipuncture needle. Always employ a designated safety transfer device.
  • Tube Holder Draws: In this scenario, carryover occurs within the needle of the tube holder as tubes are switched.

The Impact of Disregarding Order of Draw

Let’s explore some specific examples of how neglecting the order of draw can impact test results:

  • Potassium Test: If EDTA from a lavender-topped tube (high in potassium) carries over to a potassium test tube (green, red, gold, or speckle-topped), the potassium level might appear falsely elevated. This could lead to a potentially life-threatening situation due to a misdiagnosis.
  • Coagulation Studies: Contamination from a clot activator in a red-topped tube can falsely shorten prothrombin time (PT) or activated partial thromboplastin time (aPTT) results in a blue-topped (coagulation) tube.
  • Blood Culture Contamination: If blood cultures aren’t collected first, bacteria from non-sterile stoppers of other tubes can contaminate the culture bottles, leading to false-positive results.

The Recommended Order of Draw

Thankfully, by adhering to a well-established order of draw, we can mitigate the risks of additive carryover. This standardized order ensures that any potential carryover has minimal impact on test results. Here’s the recommended sequence:

  1. Blood Culture Tubes: These are filled first due to their sensitivity to contamination.
  2. Sodium Citrate Tubes (Blue-Stopper): Used for coagulation testing.
  3. Serum Tubes (Red, Gold, Speckled-Stopper): For tests requiring clot formation and serum separation.
  4. Heparin Tubes (Green-Stopper): Suitable for tests requiring preserved whole blood.
  5. EDTA Tubes (Lavender-Stopper): Used for tests requiring complete blood count (CBC) and blood banking.
  6. Glycolytic Inhibitor Tubes (Gray-Stopper): For tests requiring preservation of glucose levels.

It’s important to note: Some facilities might have conducted internal studies supporting slight variations to the recommended order. Always prioritize your facility’s established protocol if it’s backed by reliable evidence.

The Evolution of the Order of Draw

The order of draw has undergone revisions over time to adapt to advancements in phlebotomy practices. A significant change occurred in 2003 due to the industry-wide shift from glass to plastic blood collection tubes. Glass tubes naturally activate clotting, while plastic doesn’t. To compensate, manufacturers introduced clot activators within plastic tubes. The pre-2003 order placed serum tubes before the blue-topped coagulation tube, posing a carryover risk. Therefore, a consensus was reached among major U.S. tube manufacturers in 2003 to relocate serum tubes after the coagulation tube during a revision of the venipuncture standard.

How to Remember the Order of Draw

Here are some helpful strategies to solidify the order of draw in your memory:

  • Mnemonic Devices: Phlebotomists often utilize mnemonics, easy-to-remember phrases that connect to the order of draw. For instance, “Young Bodies Really Should Get Large Grains” corresponds to the color-coded tubes (Yellow, Blue, Red, SST, Green, Lavender, Gray).
  • Order of Draw Bracelets: While some utilize order of draw bracelets as a reference, it’s crucial to internalize this knowledge for independent practice without relying on external aids.

Beyond Memorization: Mastering the Order of Draw

While memorization plays a role, a deeper understanding of the order of draw empowers you to adapt effectively in various scenarios. Here are some additional considerations:

  • Facility Protocols: Always prioritize your specific facility’s established order of draw, especially if it’s based on sound scientific evidence.
  • Tube Compatibility: Familiarize yourself with the different types of tubes used at your facility and their corresponding tests. This knowledge allows you to anticipate potential carryover risks and adjust accordingly if necessary.
  • Patient Positioning: While the ideal scenario involves tubes filled in a horizontal position to minimize carryover, patient positioning might not always allow for this. In such situations, maintain awareness of the order of draw and prioritize tubes with the highest risk of carryover contamination.

The Importance of Expertise in Phlebotomy

A skilled phlebotomist understands the order of draw not just as a sequence, but as a critical component of ensuring patient safety and accurate test results. At [Phlebotomy Now], we prioritize education and training to equip phlebotomists with the knowledge and skills necessary for excellence in this field.


The order of draw stands as a fundamental principle in phlebotomy. By adhering to this established sequence, phlebotomists safeguard the integrity of blood samples and contribute to accurate diagnoses and effective patient care. Remember, memorization is a stepping stone; strive for a deeper understanding of the order of draw and its rationale for seamless implementation in real-world scenarios.

Blood Tube Types and Corresponding Tests

  • Red-top tube (serum clot activator tube): Used for tests requiring serum, such as electrolytes, cholesterol panels, thyroid function tests, and liver function tests.
  • Blue-top tube (sodium citrate tube): Used for coagulation studies, such as prothrombin time (PT) and activated partial thromboplastin time (aPTT).
  • Green-top tube (lithium or sodium heparin tube): Used for tests requiring unclotted whole blood or plasma, such as blood gas analysis, some hormone tests, and therapeutic drug monitoring.
  • Lavender-top tube (EDTA tube): Used for tests requiring whole blood with an anticoagulant, such as complete blood count (CBC) and blood smears.
  • Gray-top tube (sodium fluoride/potassium oxalate tube): Used for tests requiring blood sugar preservation, such as glucose levels.
  • Gold-top tube (serum separating tube): Similar to the red-top tube, but with a gel separator for faster serum separation. May be used for the same tests as the red-top tube.
  • Pink-top tube (EDTA tube): Less common than lavender-top tubes, used for some blood bank tests and blood smears.

Complications of Not Following the Order of Draw

  • Inaccurate test results: Additive carryover from one tube to another can alter test results, leading to misdiagnosis or delayed treatment.
  • Misdiagnosis: For example, potassium carryover from a lavender-top tube to a green-top tube can falsely elevate potassium levels, potentially leading to a misdiagnosis of hyperkalemia (high potassium).
  • Delayed treatment: Inaccurate test results can cause delays in starting appropriate treatment.
  • Wasted resources: If blood samples are unusable due to order of draw errors, new blood draws may be needed, costing additional time and money.

Best Practices for Phlebotomists to Ensure Accurate Blood Draws

  • Site selection: Choose a suitable vein that is visible, palpable, and stable. Common sites include the median cubital vein in the arm and the cephalic vein in the forearm.
  • Needle gauge: Select the appropriate needle gauge based on the patient’s vein size and blood viscosity. A thinner gauge needle is preferred for smaller veins.
  • Tourniquet application and release: Apply the tourniquet correctly, proximal to the venipuncture site, and release it promptly after blood flow is established.
  • Aseptic technique: Maintain a sterile environment throughout the procedure to minimize the risk of infection.
  • Mixing tubes gently: Gently invert tubes according to manufacturer’s instructions to ensure proper mixing of additives with blood.
  • Proper labeling: Clearly label all blood collection tubes with the patient’s name, date, and time of collection.
  • Order of draw: Strictly follow the established order of draw to prevent additive carryover and ensure accurate test results.

By incorporating these best practices, phlebotomists can significantly reduce the risk of errors and ensure the collection of high-quality blood samples.

FAQs about the Order of Draw in Phlebotomy

Why is the order of draw important?

  • The order of draw prevents inaccurate test results caused by additive carryover from one tube to another.

What happens if you don’t follow the order of draw?

  • Disregarding the order of draw can lead to inaccurate test results, potentially causing misdiagnosis and delayed treatment.

What is the recommended order of draw?

  • The recommended order is:
    • Blood Culture Tubes
    • Sodium Citrate Tubes (Blue-Stopper)
    • Serum Tubes (Red, Gold, Speckled-Stopper)
    • Heparin Tubes (Green-Stopper)
    • EDTA Tubes (Lavender-Stopper)
    • Glycolytic Inhibitor Tubes (Gray-Stopper)

How can I remember the order of draw?

  • Use mnemonics like “Young Bodies Really Should Get Large Grains” or order of draw bracelets (but aim for deeper understanding).

What should I do if my facility has a different order of draw?

  • Always prioritize your specific facility’s established protocol if it’s backed by reliable evidence.

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Additional Resources

  • National Phlebotomy Association: [National Phlebotomy Association ON National Phlebotomy Association] 
  • American Society for Clinical Pathology:
  • Clinical and Laboratory Standards Institute:

By following the recommendations in this article and consulting these valuable resources, you can embark on a rewarding career as a phlebotomist, confident in your ability to deliver accurate and reliable blood samples.

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