The rainbow colors in our phleb area

Ever wondered why phlebotomists/medtechs fill different tubes in one extraction?

Here is why:

- Each tube has different kinds of what we called as ANTIcoagulants. An anti-coagulant is a substance (be it liquid or spray-dried) inside the tube that prevents the blood from clotting. Take note, some tests require PLASMA as it retains some substances essential for testing. Also, there are also tubes that needs the blood to be clotted so as to obtain what we called as SERUM.

Now, you maybe asking what anticoagulants are inside each tube and which one hasn't? Let me explain to you starting from the left tube up to the last tube.

First, the phlebotomist makes sure to practice the correct ORDER OF DRAW to avoid anticoagulants mixing up (coz it could affect some results if not).

• Light Blue-Top Tube

This tube contains sodium citrate as an anticoagulant. We use this for coagulation studies such as Prothrombin time (PT), APTT, D-dimer, and Fibrinogen split product in the lab.

I've come across different kinds of citrated tubes having different fill lines but what matters most is that the tube must be completely filled on the line. The ratio of blood to anticoagulant (mostly 9:1) is critical for valid prothrombin time results.

• Light orange tube

This is the Serum Gel Tube. This tube contains a clot activator and serum gel (thixotropic gel) separator. This is commonly used for chemistry tests. Not recommended for clotting time studies and in crossmatching though.

• Red-Top Tube

This tube is a plain tube. That means no anticoagulant. This is widely used for the collection of serum for chemistry tests (Fasting blood sugar, lipid profile, serum electrolytes) as well as clotted blood for immunoserological tests (Hepatitis panel, Thyroid Panel, Allergy panel).

• Green-Top Tube 

This tube contains sodium heparin -- used for collection of heparinized plasma or whole blood for special tests such as Venous Blood Gas, Ionized Calcium in our case. This is a good tube for parallel testing in coincide with the red top tubes in chemistry.

• Lavender-Top Tube (EDTA)

This tube contains EDTA as an anticoagulant -- used for most hematological procedures (Complete blood count, retic ct, peripheral smear morph), Troponin I, and HBA1C.


Invertion is a must after getting the samples filled inside the tube. This is to ensure that the blood is getting mixed with the anticoagulant. There maybe times the phlebotomist has to recollect blood because of the clots being detected in the machine (like in CBC where Platelet clumps could lead to inaccurate results if not to be examined manually through the patient's blood smears).

These are just commonly used blood collection tubes in our laboratory. Yes, there are other tubes that you may come across with. So check out my other posts later.

REFERENCES:

www.mayomedicallaboratories.com/customer-service/faq/specimen/collection-tubes