Does the additive-free tube without separating gel need to be inverted and mixed after blood collection?

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There are many types of vacuum blood collection tubes used for blood testing. The safety caps of the tubes are colorful, representing different functions. Usually, whether it is an anticoagulant tube or a coagulant tube, in order to make the blood and reagents fully uniform After contact, the blood needs to be mixed upside down. So, do the red cap blood collection tubes that do not contain separating glue or other additives also need to be mixed upside down?


The additive-free tube with the red cap does not contain serum separation gel or anticoagulant, which is not conducive to sample processing, and is now used less. However, for some special testing items, such as: sex hormones, thyroid function, and maternal serum Down's screening in the second trimester , Β-HCG, etc., the results of such test items may be affected by anticoagulants, so use blood collection tubes without additives.

According to the reaction of the laboratory staff, when testing a certain index, there is a big gap between the same sample before and after the same experimental conditions, which is analyzed by the contrast experiment of inverted and mixed after blood sampling.


If you want to get a qualified serum sample, you need to mix the sample upside down after blood collection. Whether it is left at room temperature or in the incubator, you need to mix again until the blood coagulates. When a clear yellow serum is separated out, centrifuge again to get qualified. Get the serum. If the blood is not mixed upside down and placed directly on the test tube rack after the blood is collected, the cell components in the blood will naturally settle under the action of gravity, and the isolated serum will coagulate through the coagulation mechanism.


After analyzing and investigating various reasons, it was found that although the two tubes of blood samples were both clear and transparent yellow serum, the samples that were mixed upside down had serum microagglutination that was difficult to detect with the naked eye, and the upper layer of cells had gelatinous serum. Frozen coagulated serum! After using a disposable sterile cotton swab stick to agitate and squeeze the jelly-like serum and re-centrifuge, the test results on the machine again are consistent with the comparison group.


It can be seen from the above case that whether the additive-free tube is inverted and mixed for some test items will have different results. In fact, according to my analysis, it is incomplete to categorize the cause of the difference as upside-down and mixing. It may also be related to the incomplete coagulation. Even if the coagulation is complete, the fibrin is mixed in the serum due to the layered coagulation of the cells and fibrin. Medium may also interfere with the results. It can be solved by adding separating glue but not adding anticoagulant or accelerator. Desheng has rich experience in serum separation gel and can improve sample quality through separation gel.