Phlebotomy Tips: How to Properly Mix a Blood Sample to Prevent Clotting

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. 

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Here’s a quick Jeopardy challenge: The second most common reason laboratories reject blood samples.

If you responded, “What are clotted samples,” then you are correct! 

Red blood cells are fragile, which means they won’t tolerate a lot of turbulence in the tube. That’s why learning to properly mix a blood sample is a surefire way to prevent a laboratory rejecting your blood sample for clotting. 

Let’s review why mixing a blood sample properly is so underestimated and how you can teach proper mixing.

Why is mixing a blood sample to prevent clotting so underestimated? 

There are several different styles and approaches to mixing tubes. Here are a few. 

• Jiggling the tube: This involves shaking the tube back and forth between your fingers, like trying to unlock a door with the wrong key 

• The bartender mix: Like Tom Cruise in Cocktail, shaking the tube like a cocktail shaker is one overly aggressive approach to mixing a sample

• The juggler: Imagine a circus routine of tossing the tube in the air (please, don’t do this)

• Shaking it up: Like shaking a bottle of soda with your thumb sealing the bottle top 

It’s not difficult to mix a tube, however, it’s important that whenever we’re teaching someone to mix tubes that we’re methodical about teaching the proper method. By teaching the proper technique, fewer samples will reach the lab and be rejected for something easily avoidable.

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How do you teach proper mixing?   

For this demonstration, you’ll need to find a large prop to demonstrate with. If you have a large inflated tube, that’s perfect. Otherwise, any long cylinder object with a liquid and air pocket you have lying around will do, like a full two-liter soda bottle. 

What you want to demonstrate is that when a tube of blood is filled, there is headspace at the top with an air bubble. Because tubes have additives coated with to the side, the air bubble will travel the length of the tube and do all the mixing. 

When the tube is inverted and we give the air bubble time to rise, that air bubble will create friction along the tube and erode the additives. This will assist you in mixing the sample. 

Here are three easy steps to properly mixing the tube: 

1. Invert the tube so that the air bubble has time to travel the length of the tube. 

2. Once the air bubble has risen to the tube’s curved bottom and is above the blood again, pause, and then invert it again until it returns to the top portion of the tube (the cap end). That’s one inversion. 

3. Repeat the process five times for all anticoagulant tubes. 

That’s it! Following this process will significantly lower your sample rejection rate due to clotted samples. 

The most important takeaway to remember is: Let the air bubble do the mixing. 

Lastly, shaking is breaking. 

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!