Samples taken during a blood test are collected in a series of small colored tubes. But do you know what these tubes are called and what is their role? And did you know that there are also some for urinalysis?

The Vacutainer brand has been registered by the company Becton-Dickinson. BD Vacutainer® tubes are manufactured in the USA and UK. They are used to collect blood plasma or urine samples with a view to performing their biochemical and / or serological analysis for blood, and microbiological / cytological and / or chemical for urine.

Composition of tubes

• Materials: the tubes are in polyethylene and their sealing cap in synthetic elastomer covered with a plastic cap;
• The inside of the tubes is sterilized by gamma ray in accordance with the ISO 11137 standard;
• Their nominal vacuum is 2 to 10 ml, which corresponds to their capacity;
• They contain chemical components specific to the analysis to be performed. Depending on the nature of these components, the tubes are differentiated from each other by their cap color;
• They are packaged by 100 on film-coated racks;
• They must be kept at a temperature between 4 ° C and 25 ° C and be stored out of direct sunlight.

Vacutainer tubes are used to condition samples of biological fluids in a suitable medium to allow their transport and subsequent analysis.

They are designed so that at no time the sampler is in contact with the blood or urine to be analyzed. Safety comes first.

Blood collection tubes

Each type of tube is identified by its cap color. This corresponds to the analysis which must be carried out on the plasma sample. The main tubes used are:

• Green tube to perform an ionogram, which is the dosage of the main electrolytes in the blood: calcium, sodium, potassium, chlorine, magnesium, bicarbonates. This tube contains heparin to prevent the blood from clotting without bringing in ions that would distort the results of the analysis;
• Purple tube for the complete blood count (CBC) in order to know the composition of red blood cells and lymphocytes in the blood. This tube contains EDTA (ethylenediaminetetraacetic acid) as an anti-coagulant;
• Blue tube for hemostasis, i.e. blood clotting. This tube contains citrate, an anticoagulant which acts in a reversible manner;
• Gray tube for blood sugar, or blood sugar level. The fluorine contained in this tube inhibits the action of glycolysis enzymes, thus preventing the degradation of glucose in the sample.

The 4 tubes above are centrifuged in the analysis laboratory in order to recover the plasma and the globules in the pellet.

• Red tube for biochemical (cholesterol, triglycerides, uric acid, etc.) and immunological (antibody assay) analyzes. Silica microparticles make it possible to activate coagulation, and centrifugation will make it possible to isolate the serum for carrying out the analyzes;
• Yellow tube to separate the plasma from the blood cells during centrifugation thanks to the presence of a separating gel.

Collection tubes for urine

• Khaki green tube for urinary microbiological and cytological analyzes (ECBU). This tube contains bacteriostatic agents to stop the growth of bacteria without killing them;
• Beige tube for biochemical analyzes. It does not contain any additives.

The stages of operation

The principle of operation of the Vacutainer devices is to aspirate the blood or the urine thanks to the vacuum which exists in the tube (vacuum means empty in Latin). The filling capacity of the tubes is thus determined by their nominal vacuum. Once the tubes are full, there is no more vacuum inside and the suction stops spontaneously. There is therefore no risk of overflow or of contact with blood or urine for the sampler or the environment.

The collection tubes are then analyzed directly on the automated systems in the laboratory without any need to intervene or carry out content transfers. Here again, the risks of contact with body fluids are almost nil.

Blood sample

1. Assembly of an epicranial device with a Vacutainer collection body;
2. tourniquet is placed on the arm upstream of the sampling site, the arm must always be tilted downwards so that the sampling is done below the puncture point;
3. disinfection of the puncture site with 70 ° alcohol;
4. sting;
5. insert the 1st sampling tube into the body of the Vacutainer and perforate its stopper (the order of filling the tubes must be considered);
6. release the tourniquet;
7. the vacuum in the tube has the effect of sucking blood into it;
8. when the tube is full and the blood stops flowing, remove it;
9. homogenize the tube by 8 to 10 slow inversion (only 5 for the tubes with gel);
10. insert the next tube, and repeat the same procedure;
11. remove the last tube before removing the needle to avoid aspiration of tissue.

Urine sample

• If the patient is independent, he collects his urine himself in a suitable container: sterile 120 ml jar or 3-liter container (to collect urine over 24 hours), each equipped with an integrated cannula adapted to the collection tubes . The nurse can transfer the urine to the analysis tube (s) without risk of contaminating the samples;
• If the patient is probed, the urine is collected directly at the sampling site of the probe using a needle fitted with an adapter into which the Vacutainer tube is inserted;
• If it is a baby, the collection will be done directly in the self-adhesive pocket in which the transfer cannula and the collection tube will be inserted.

Precautions to take

The collection of biological samples in Vacutainer tubes guarantees a sample under conditions of optimal sterility and safety.

Some tests require the patient to be fasting, including blood chemistry and blood sugar tests.

These devices are reserved for medical use and their sale is therefore restricted to the medical and hospital environment.

The different models

A complete collection unit contains an epicranial needle connected to the PVC tubing, a Luer adapter where the tube will be inserted, and a collection body.

These elements can be acquired separately:

• Luer screw adapter;
• sample body;
• sampling needle with bayonet attachment on a sampling body.

Safety standards

BD Vacutainer® tubes are in vitro diagnostic medical devices and are therefore subject to European safety standards 98/79 / EC.

Their lifespan is approximately 16 months.