Career Development

Importance of Order of Draw Blood Bottles – Use and Best Practice

Phlebotomy Training Institute
8 Mins Read

When you get a blood test, a healthcare professional (phlebotomist) collects blood in a series of vials or tubes. But did you know the order in which they fill these tubes is crucial for accurate test results? This order is called the Order of Draw. So, now you might wonder, “What’s the function of these Order of Draw blood bottles?”

Here’s the brief: These blood bottles ensure that different additives in tubes don’t mix, keeping your blood sample safe and making sure your test results are accurate. They help maintain the reliability of diagnostic testing by organising the sequence in which blood is collected during venipuncture.

In this blog, we’ll delve into the importance of these blood bottles and how they safeguard the integrity of your blood tests.

Scientist in blue latex glove holding Hepatitis A test sample.

What is the Order of Draw?

The order of draw refers to the specific sequence in which blood samples are collected in tubes during phlebotomy. It’s important to maintain this order to prevent contamination of the blood samples and ensure accurate test results.

There are two main reasons for the order of draw:

  • Avoiding clotting: Certain tubes contain additives that prevent blood clotting. If a tube containing an anticoagulant (clot-preventing) additive is drawn after a clot activator tube, some of the clot activators could be carried over into the anticoagulant tube, ultimately causing clotting in the undesired tube.
  • Avoiding additive interference: Different tubes contain different additives that can interfere with tests if they are mixed with blood from a previous tube.

You can check out a book based on WHO Guidelines on Drawing Blood.

Woman holding blood test tubes wearing latex gloves in modern laboratory setting.

Typical Order of Draw

Here’s the typical order of draw recommended by the Clinical and Laboratory Standards Institute (CLSI):

  • Blood Culture Bottles: This is the first step. These tubes help find bacteria or fungi in the blood, which helps diagnose infections.
  • Sodium Citrate: It stops blood from clotting and enables accurate measurement of clotting factors and coagulation
  • Red Top Tubes (Serum): This tube doesn’t have anything added to it. It’s used for different tests as needed, like looking for specific antibodies or signs of diseases.
  • Serum Gel: This tube has a gel that separates the liquid part of blood (serum) from the blood cells. It makes it easier to test the serum for things like proteins, hormones, and enzymes.
  • Green Top Tubes (Heparin): Similar to serum gel tubes, but used to separate plasma from blood cells. Plasma is tested for things like electrolytes and proteins.
  • Purple Top Tubes (EDTA): This tube has a substance that stops blood from clotting by grabbing onto calcium. It’s used for tests like counting blood cells and checking their shape.
  • Gray Top Tubes (Oxalate/Fluoride): Stops sugar in the blood from breaking down. It’s used to keep blood sugar levels accurate in tests like glucose tolerance tests.

Visit our insightful blog to learn more about the correct order of blood draws.

Hand holding a test tube analysing a blood sample for COVID-19 (coronavirus).

What is the Importance of Order of Draw Blood Bottles?

The Order of Draw in blood collection is very important. It helps keep the blood samples pure and makes sure the test results are right. Let’s talk more about why these blood bottles are so important.

Preventing Contamination

One of the primary reasons for following the order of draw is to prevent sample contamination. Each tube contains different additives designed to preserve the blood for specific tests. Mixing up the order could lead to additives from one tube contaminating another, affecting the test results.

Preserving Blood Sample Integrity

Different tests need different parts of the blood, like serum or plasma, and each needs special stuff added, like additives or anticoagulants. By following the Order of Draw, healthcare professionals ensure that each tube contains the appropriate additive for the intended test. This keeps the blood sample good and helps with correct diagnosis and treatment.

Minimising Hemolysis

Hemolysis, the rupture of red blood cells, can occur during venipuncture due to factors such as excessive vacuum pressure or traumatic needle insertion. So, when blood cells break during testing, the results may not be reliable, and the test might need to be done again. This can be a hassle for patients and delay getting a diagnosis. Following the right order helps stop blood cells from breaking by reducing agitation and trauma to blood cells, thereby preserving sample quality and diagnostic accuracy.

Ensuring Test Validity

Tubes have special things inside to keep the blood good for certain tests. Following the right order makes sure each tube has the right stuff for the test we want. This is important so we can trust the test results and make the right decisions for patient care.

Enhancing Laboratory Efficiency

Following the Order of Draw helps labs work better. It makes sure samples are labelled and tested in the right order so things don’t get mixed up. This helps labs work faster and more accurately, which means patients get their results quicker and with less chance of mistakes.

In addition, if you’re interested in gaining a thorough knowledge of how to gain phlebotomy work experience as a beginner, visit our informative blog to learn the process.  

Hands with white surgical gloves pouring blood from pipette onto a blood slide.

Upholding Quality Standards

Following rules like the Order of Draw is important to make sure healthcare is good. It shows that healthcare workers are serious about doing their jobs right and giving patients the best care possible. This helps keep tests accurate and patients safe.

Patient Safety

At the end of the day, everything boils down to patient safety. Following the correct order of draw isn’t just about getting accurate test results; it’s about ensuring the well-being of the individuals relying on those results for diagnosis and treatment.

Training and Education

Proper training is essential for healthcare professionals involved in blood collection. Training programs emphasise the importance of following standardised procedures, including the order of draw, to minimise errors and ensure patient safety.

Quality Control Measures

In addition to proper training, quality control measures play a crucial role in maintaining accuracy in blood collection. Regular audits and checks help identify any issues with the process and ensure compliance with established phlebotomy protocols.

Best Practices

So, what can healthcare professionals do to ensure they’re following the correct order of draw? First and foremost, familiarise themselves with the recommended sequence and double-check before starting the procedure. Additionally, labelling tubes immediately after collection can help prevent mix-ups.

Regulatory Compliance

Regulations and standards set by governing bodies outline specific guidelines for blood collection procedures, including the order of draw. Compliance with these standards is a must for maintaining quality and consistency in healthcare practices.

Technological Advancements

Advancements in technology have also played a role in improving blood collection processes. Automated systems and barcode labelling help make the process smoother and reduce mistakes, making test results more reliable.

Besides, if you want to begin a career in phlebotomy, visit our insightful blog or step-by-step guide that covers the essential information needed to commence a career in this field.

A hand in white surgical glove holding blood sample tube on blue background.

Important Things to Keep in Mind

Here are some important rules for healthcare workers to follow to make sure they collect and test blood samples correctly.

Let’s get into the details.

  • Expired sample bottles won’t be accepted, so always check the expiry date before using them.
  • Tubes have additives to keep the blood good for testing. Don’t transfer blood between tubes if a mistake happens.
  • Make sure to use the right stuff in the tubes to prevent blood from clotting.
  • When using a needle to collect blood from a vein, use adult bottles whenever possible. Blood cultures should be taken first if needed.
  • Fill tubes to the marked level to keep the right ratio of blood to tube additives. Even serum tubes have something to prevent clotting.
  • After filling, gently turn the tubes over 6-8 times to mix them well, but don’t shake.

Wrapping Up

To sum up, the Order of Draw Blood Bottles is super important for getting accurate and reliable test results. Healthcare workers use this system to keep blood samples clean, avoid mixing them up, and make sure patients get the best care possible.

As we know, having the right training in phlebotomy from a recognised institution is really important. This is because it teaches you all the right ways to draw blood and the correct order to do it. Phlebotomy Training Institute is one such place where you can learn everything about drawing blood correctly. If you want to become a phlebotomist and learn from experts, this institute can help you achieve your goal.

You can gain both theoretical knowledge and practical skills by enrolling our couses on Basic and Advanced Phlebotomy Competency Training, covering Cannulation and catheterisation. This CPD-accredited and NHS-accepted certified training prepares you to be a skilled phlebotomist through a mix of hands-on practice and online learning.


1) Can a single wrong tube order mess up all the tests?

Not necessarily. The severity of impact depends on the tests ordered and the specific additives involved.

2) Who determines the order of blood draw?

The order is established by medical guidelines and followed by trained phlebotomists.

3) Is the order of draw always the same?

The general order is widely used, but slight variations might exist based on lab protocols or specific tests.

4) Where can I find more information about blood draw procedures?

You can consult your doctor’s office, laboratory website, or reliable medical information websites.

5) What are pre-analytical errors?

Pre-analytical errors are mistakes that occur before a blood sample even reaches the lab for testing, including issues with collection, handling, and storage. These errors can lead to inaccurate test results.


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