You've Been Mixing Wrong for 25 years?

If you didn't wait so long it wouldn't have clotted

 Or: "It can't be clotted, I pulled out the clot before sending it, just RUN IT" Okay I ran it. Your patient's platelet count is 22. "Oh boy, gotta see if the Doc will want a dose of platelets ordered!"

Tubes clot because of poor technique, rough draw, excessive tissue factor inlet on a heelstick, improper mixing to ensure anticoagulant coverage, etc. Not because the tube is sitting waiting to be manually run. In fact, we ream it for clots BEFORE we run it, as soon as we receive the tube. It's still clotted, please mix your tubes next time. "But I've been doing this for 25 years! I'm not wrong"

You can't argue with that kind of attitude

The NICU got so fed up, they were invited to come watch our process from specimen receipt to resulting the microtainer CBC. They still were not convinced that it wasn't the labs fault. 

Fun facts:

No calcium -- No clots

As soon as you strike through the endovasculature you've activated the initial steps of the coagulation cascade. You need to quickly stop this through the use of anticoagulants. 

The anticoagulant in a "purple top" tube for CBC is EDTA or Ethylenediaminetetraacetic acid. Actually it's usually K2EDTA or K3EDTA, a potassium salt of the compound. The anticoagulant is sprayed on the inside of the tube in the hopes that when blood enters the tube, it will be gently mixed 8-10 times to ensure a full and even coat. You want full contact with the EDTA. EDTA works by chelating calcium in the blood. This means that EDTA grabs onto calcium to form a completely new complex, rendering the calcium unusable. As we ALL remember from the coagulation cascade, you need calcium (Ca2+)  to begin clot formation. 

Why do our tubes clot still then?

-Not mixing well enough
-Slow draw (clots before the draw is complete and before mixing of the tube)
-Drawing into a non-anticoagulated syringe
-Over-filled tubes (you need SOME space in the tube to be able to mix it properly.)


Please please please mix your tubes


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