Understanding Blood Draw Order in Phlebotomy
Understanding Blood Draw Order in Phlebotomy

Are you curious about the correct blood draw order in Phlebotomy? First I have a question for you. Have you ever wondered why your blood is drawn in a specific order during a blood test? 

See, it’s not just random pricking! In phlebotomy, the order in which blood samples are collected is crucial for ensuring accurate test results. This order is called the “order of draw” and plays a vital role in maintaining the integrity of your blood sample.

Ok, now if you want to understand the mechanism of blood drawing order in Phlebotomy then this piece of content is perfect for you. In this blog post, we are going to analyze the drawn order. Here we discuss the correct order, its importance, and how you can remember the correct order easily. Let’s dive into the deep!

Key Takeaway Of This Article

  • Blood Draw Order Definition
  • Why is Order of Draw Important?
  • What happens if you draw blood in the wrong order?
  • Heroes of the Order
  • The Correct Blood Draw Order
  • FAQs

What is the Blood Draw Order in Phlebotomy?

Blood draw order in phlebotomy refers to the specific sequence in which blood samples are collected during a blood test. This order is essential for ensuring the accuracy of test results.

Understanding Blood Draw Phlebotomy

Why is Order of Draw Important?

Blood is a complex mixture of cells and fluid. Different tests require analyzing various components of this mixture. Each blood collection tube contains specific additives, like anticoagulants or clot activators, that help preserve the blood sample for a particular type of test.

If the blood draw order is not followed, these additives can accidentally mix between tubes, altering the composition of the blood sample. This can lead to inaccurate test results, potentially causing misdiagnosis or delays in treatment.

Read More: Phlebotomy: Definition, Types & Purpose

What happens if you draw blood in the wrong order?

Drawing blood in the wrong order can potentially lead to inaccurate test results, although the severity of the impact depends on several factors. Here’s a breakdown of the possible consequences:


  • Blood Culture Tubes (Yellow): These are the most susceptible. If drawn after tubes with additives, residual amounts of those additives can interfere with microbial growth, potentially leading to false negative results (missed infections).
  • Other Tubes: Contamination is less likely with other tubes, but it can still happen. For example, drawing a serum tube (red or gold) before a heparin tube (green) could introduce trace amounts of heparin, affecting some tests that measure clotting times.

Altered Sample Composition:

  • Serum vs. Plasma: Incorrect order can affect the separation of blood components. Drawing an EDTA tube (lavender) before a serum tube (red) can lead to some white blood cells ending up in the serum, impacting tests that analyze specific components in serum.
  • Cell Function: Anticoagulants like EDTA can affect the function of some blood cells. Drawing an EDTA tube before a heparin tube (green) for tests that analyze cell activity might lead to slightly altered results.

Misleading Results:

  • Certain Analytes: Some tests measure specific chemicals in the blood. If the order of draw allows even a small amount of an additive from another tube to contaminate the sample, it can alter the measured levels of those chemicals, leading to misleading results. For example, drawing a blood sugar tube (gray) before an EDTA tube might cause a slight decrease in the measured blood sugar level.

Generally, the consequences of a slightly wrong order may be:

  • Need for redraw: If the lab suspects contamination or altered sample composition due to order deviation, they might request a redraw to ensure accurate results.
  • Delayed Diagnosis/Treatment: In critical situations, inaccurate results due to order errors could lead to delays in diagnosis or treatment.

However, it’s important to note that:

  • Modern Techniques: Modern blood collection systems and lab analysis techniques are often quite robust and can sometimes compensate for minor order deviations.
  • Highly Trained Professionals: Phlebotomists are extensively trained on the order of draw and take great care to follow it.
  • Lab Alertness: Labs are aware of potential order errors and have protocols in place to identify and address them.
Blood Draw in Phlebotomy

Read More: Importance Of Safety With Phlebotomy

The Heroes of the Order: Blood Collection Tubes

Imagine a team of superheroes with a unique power to preserve a specific aspect of your blood. That’s how blood collection tubes function! Here’s a breakdown of the most common tubes and their superpowers:

  • Blood Culture Tubes (Yellow): These champions fight invisible enemies – bacteria and fungi. They have no additives and allow blood to grow any microbes present, helping diagnose infections.
  • Sodium Citrate Tubes (Light Blue): These warriors prevent blood clotting. They are perfect for tests that require studying blood cells and platelets in their natural state.
  • Serum Tubes (Red or Gold with/without Clot Activator & Gel): These mighty tubes let the blood clot and then separate the liquid portion, called serum. They are used for a wide range of tests, including cholesterol, hormones, and electrolytes. Red tubes contain no additives, while gold tubes have a clot activator that speeds up clotting. Some serum tubes may also have a gel separator that further isolates the serum for easier analysis.
  • Heparin Tubes (Green): These masters of motion keep blood from clotting for tests that analyze blood flow and cell function. They come in different shades (dark or light green) depending on the specific type of heparin used.
  • EDTA Tubes (Lavender): These champions bind calcium, preventing blood clotting. They are ideal for tests that require studying complete blood counts (CBCs), which involve analyzing different types of blood cells.
  • Glycolytic Inhibitor Tubes (Gray): These specialists preserve blood sugar levels by preventing the breakdown of glucose in the blood. They are crucial for tests that measure blood sugar (glucose) levels, especially important for diabetes management.

The Correct Blood Draw Order: A Super Team in Action!

Now that you’ve met the blood collection tube team, let’s see how they work together in the order of draw:

  1. Blood Culture Tubes (Yellow): Since any contamination can affect their ability to detect microbes, they are drawn first to minimize the risk of interference from additives in other tubes.
  2. Sodium Citrate Tubes (Light Blue): These are next in line because even small amounts of heparin or EDTA from other tubes can alter clotting times.
  3. Serum Tubes (Red or Gold): These come after the tubes requiring no additives to avoid contamination. Red tubes are drawn before gold tubes as the clot activator in gold tubes can slightly alter some test results.
  4. Heparin Tubes (Green): Since heparin doesn’t significantly affect clotting tests or cell counts, it can be drawn after serum tubes.
  5. EDTA Tubes (Lavender): These come last because EDTA can interfere with some tests performed on serum.
Correct Blood Draw Order

Remembering the Right Blood Draw Order: Fun and Mnemonics!

Memorizing the order of the draw can be a challenge. Here are some fun ways to remember it:

  • The “Young Bodies Really Should Get Large Grains” Mnemonic: Each word corresponds to the first letter of the tube color (Yellow, Blue, Red, Serum [Gold], Green, Lavender, Gray).
  • Imagine a Colorful Superhero Team Story: Create a story where the different colored tubes work together in a specific order to defeat the villain of inaccurate test results.

Bottom Line

While modern techniques and trained professionals can sometimes compensate for minor order deviations, following the blood order of draw is still the best practice. It minimizes the risk of errors and ensures the accuracy of your blood test results, which is crucial for proper diagnosis and treatment. If you have any concerns about the order during your blood draw, don’t hesitate to ask the phlebotomist!


What is the correct order of draw in phlebotomy?

The correct order of draw in phlebotomy is:
1. Blood Culture Tube (Yellow)
2. Sodium Citrate Tube (Light Blue)
3. Serum Tube (Red, then Gold)
4. Heparin Tube (Green)
5. EDTA Tube (Lavender)

What are the 7 basic steps to a blood draw?

The 7 basic steps to a blood draw are:
1. Patient identification and verification
2. Site selection and preparation (applying tourniquet)
3. Venipuncture (inserting a needle into a vein)
4. Blood collection (filling tubes in the correct order)
5. Tube mixing and labeling
6. Hemostasis (stopping bleeding at the puncture site)
7. Patient care and disposal of sharps

Why is the order of draw important in phlebotomists?

The order of draw is crucial to ensure the accuracy of your blood test results. Each blood collection tube contains specific additives to preserve your blood for different tests. If the order is not followed, these additives can contaminate other tubes, altering the composition of your blood sample and leading to inaccurate results.

Who determines the order of blood draw for a specific test?

While the order of draw is a general guideline, there can be variations depending on the specific tests ordered. Ultimately, the lab will determine the exact order needed for accurate results. Phlebotomists are trained in these variations and will follow the lab’s instructions.

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