Why Use a Bunch of Colorful Plain Blood Collection Tubes?

Every time you have blood drawn, you can always see a handful of multi-colored blood collection tubes in your hand. It's just drawing blood, so why do you need to use so many tubes of various colors?

In fact, the tubes used for blood collection in hospitals are professionally named "vacuum blood collection tubes" and are classified as Class II medical devices. They are usually used in conjunction with venous blood collection needles. Using multiple tubes for blood collection is designed to reduce the chance of cross-contamination and to facilitate the next steps in testing. The different colors further distinguish the tubes based on their intended use.

Why use several different plain blood collection tubes for a single blood draw?

Blood collection typically requires testing for several different items, each necessitating different blood components. Plain blood collection tubes can meet the needs for preprocessing and preserving blood samples for different tests. Hence, multiple tubes are used to collect different samples separately.

Using plain blood collection tubes to collect blood according to testing purposes allows multiple blood specimens to be conveniently collected and stored, reducing the chance of cross-contamination. Meanwhile, various additives in the tubes can preprocess the blood. Plain blood collection tubes can also be directly used with centrifuges and other testing equipment, facilitating further experimental operations. Compared to drawing blood without distinguishing purpose and then processing separately, this method is much more scientific and efficient.

Why do plain blood collection tube caps come in so many colors?

It's primarily for easy identification. Distinguishing different blood collection tubes by cap color allows phlebotomists or laboratory personnel to quickly identify and collect the necessary specimens, enhancing efficiency and reducing errors. According to current standards, commonly used blood collection tubes can be divided into nine major categories, each corresponding to a different color.

Each blood collection tube has its own "specialty." Generally speaking, red tubes are the most basic and are used for routine serum biochemistry, blood bank, and serological tests; various biochemical and immunological tests may use them. Purple tubes are mostly for complete blood counts, suitable for general hematological examinations. Commonly seen in routine check-ups, they are used for complete blood counts, glycated hemoglobin, and blood type tests. In addition, gray tubes, which can quickly determine blood glucose levels, and green tubes, suitable for emergency and most biochemical tests, are also commonly seen in routine testing. There are also tubes for special purposes with unique cap colors or shapes, but these are generally rare.

Moreover, when multiple tests need to be done in one blood draw, in addition to selecting the appropriate blood collection tubes, the order of collection is also important to avoid cross-contamination of additives between tubes, which could affect test results.