Why are blood collection tube caps different colors?

Different laboratory items have different requirements for blood samples, including whole blood, serum and plasma. This requires different blood collection tubes to be matched with it. In order to distinguish the use of different blood collection tubes, different cap colors are used to mark blood collection tubes internationally. The functions of blood collection tubes with different color caps are different. There are blood collection tubes that do not contain any additives, so that different kinds of specimens can be obtained. This kind of blood collection tube is bright and eye-catching and easy to identify, which avoids the wrong use of additives during blood collection and the inconsistency of the samples sent for inspection with the inspection items.