The question of how long biological material retains its properties in cold conditions is critically important for medicine, laboratory diagnostics and donation. The answer to this cannot be unambiguous without specifying the blood type, since whole blood, plasma and individual cellular components have radically different life spans outside the body. Temperature conditions, the composition of the anticoagulant and the sterility of the packaging play a decisive role in determining the suitability of the material for subsequent use.
Modern storage technologies can significantly extend the viability of cells, however, even ideal refrigerator does not stop biological processes completely. Hemolysis, changes in environmental pH and metabolic changes occur constantly, and the task of specialists is to slow down these processes to a safe minimum. Understanding these time frames is necessary not only for doctors, but also for patients undergoing tests in order to avoid errors in diagnosis.
In this article we will analyze in detail the regulated storage periods for various blood fractions, the conditions for their maintenance and factors that can shorten these periods. You will learn why whole blood is practically not stored, how long red blood cells live and what happens to plasma when frozen. This knowledge will help you better navigate medical procedures and requirements for laboratory tests.
⚠️ Attention: Storage periods for biological fluids are strictly regulated by national and international standards (for example, orders of the Ministry of Health). In private laboratories or specific clinical settings, internal protocols may be more stringent than generally accepted standards.
Whole blood: short-term storage and limitations
Whole blood is a complex mixture of cells and plasma that quickly loses its functional properties outside the body. The standard shelf life of whole blood with an anticoagulant in the refrigerator at a temperature of +2 to +6 ° C is only 21–35 days, depending on the preservative used. The most common preservatives, such as CPDA-1, allow a maximum period of 35 days to be reached, after which red blood cells begin to be massively destroyed.
However, in modern transfusiology, whole blood has practically ceased to be used for transfusion. This is due to the fact that the patient most often does not need all the components at once, but specifically red blood cells or platelets. Long-term storage of whole blood leads to the accumulation of metabolic products that can be toxic to the recipient, so they try to process it into components in the first hours after collection.
For laboratory tests the situation is different. If biomaterial is taken for general analysis, it should be examined within several hours. Long-term storage of whole blood in a tube with EDTA (purple cap) is permissible for up to 24 hours if kept in the refrigerator, but by this time the morphology of the cells is already beginning to change. Leukocytes can swell, and platelets can aggregate, which will distort the counting results.
Red blood cells: prolongation of lifespan cells
Red blood cells are the most stable component of blood, which allows them to be stored the longest. After separating whole blood and adding a special preservative solution (for example, Adsol or SAGM), the red blood cell mass can be stored in the refrigerator at a temperature of +4 ± 2 °C until 42 days. This period is considered limiting, since after 42 days the level of hemolysis (cell destruction) exceeds acceptable safety standards.
The key factor here is the constancy of the temperature regime. Any deviation from the range +2...+6 °C sharply shortens the shelf life. If the temperature rises above +10 °C, bacteria introduced during collection begin to actively multiply in the environment, which makes the drug dangerous to life. If the blood freezes, ice crystals rupture the red blood cell membranes, turning the contents of the bag into a hemolyzed liquid unsuitable for transfusion.
It is important to note that cryopreservation is used for some rare blood types or phenotypes. In this case, the red blood cells are frozen with glycerol at a temperature below -65 °C. In this state Cryopreserved red blood cells they can be stored for up to 10 years or more. However, after thawing, they must be used within 24 hours, since the protective glycerin is washed away and the cells become vulnerable again.
| Blood component | Storage temperature | Maximum term | Conditions |
|---|---|---|---|
| Whole blood | +2...+6 °C | 21-35 days | With anticoagulant |
| RBC | +2...+6 °C | 42 days | With stabilizer solution |
| Thromboconcentrate | +20...+24 °C | 5-7 days | With constant stirring |
| Plasma (fresh frozen) | -30 °C and below | 12 months | Deep freezing |
Plasma and cryoprecipitate: freezing rules
Plasma, unlike cellular elements, does not require storage in a regular refrigerator. On the contrary, it must be frozen to preserve labile clotting factors and proteins. Fresh frozen plasma (FFP) is collected within 6–8 hours of blood collection and placed in a freezer at -30°C or colder. Under such conditions, it can be stored for up to 12 months..
There is also the concept of “plasma frozen for 24 hours.” This material has slightly less activity of some coagulation factors, but is still suitable for use as a bulk fluid. Its shelf life is also about a year if deep frozen. After thawing, plasma must be used within 24 hours, stored at a temperature of +2...+6 °C.
Cryoprecipitate stands apart - a drug obtained from plasma and containing a concentrate of coagulation factors. After defrosting the plasma at a low temperature, a precipitate forms, which is cryoprecipitate. It is stored at -30 °C for up to 1 year. After thawing, cryoprecipitate should be used within 4-6 hours, since coagulation factors quickly lose activity at room temperature.
⚠️ Attention: Re-freezing thawed plasma is strictly prohibited. This leads to irreversible denaturation of proteins and loss of the therapeutic properties of the drug.
Platelets: an exception to the cold rule
Platelets are the most capricious component of the blood. Unlike red blood cells, they cannot tolerate cold. When stored in a refrigerator (+4 °C), platelets change their shape, become irreversibly activated and are quickly removed from the recipient's bloodstream by the spleen. Therefore, they are stored at room temperature: from +20 to +24 °C.
The shelf life of platelet concentrate is extremely short and is only 5–7 days. This restriction is associated with a high risk of bacterial contamination: the nutrient medium and warm temperature are ideal for the proliferation of microbes. To prevent platelets from sticking together and provide them with oxygen, bags of platelets are placed on special rockers that provide constant gentle mixing.
To extend the life of platelets, bacteriological control or pathogen reduction (disinfection) is sometimes used, which in some countries allows increasing the shelf life to 7 days. However, even with these measures, platelet logistics remains a daunting task, requiring strict temperature control at all stages.
Blood for laboratory tests
In clinical laboratory diagnostics, the storage time of samples depends on the type of test. For biochemical analysis, blood serum can be stored in the refrigerator at +4...+8 °C for up to 48 hours. If the result is not urgently needed, the serum can be frozen at -20 °C, where it remains stable for up to 3 months, and at -70 °C for up to a year.
Hormonal studies require special attention. Many hormones are unstable, so it is recommended that serum for analysis of thyroid hormones, sex hormones or insulin be delivered to the laboratory immediately. If this is not possible, storage at +4...+8 °C is allowed for no more than 24–48 hours, but it is better to perform separation (serum separation) in the first hour and freeze the material.
For PCR diagnostics (detection of DNA/RNA viruses), whole blood or serum must also be processed quickly. When stored in the refrigerator, the viral load can change, and enzymes can destroy genetic material. Optimally, freezing at -20 °C or lower if the analysis is not carried out on the day of collection.
Why can’t you freeze whole blood for general analysis?
When freezing whole blood, the water inside the red blood cells turns into ice crystals, which rupture the cell membrane. After thawing, you will receive hemolyzed material in which it is impossible to count the cells and evaluate their shape.
Factors that shorten the shelf life
Even if the temperature regime is observed, there are factors that can spoil the blood ahead of time. One of the main enemies is light. Direct sunlight or intense artificial light can destroy some of the vitamins and proteins in the plasma and also heat the container. Therefore, blood bags are always stored in opaque refrigerators or places protected from light.
Another important factor is the integrity of the packaging. Blood collection systems are vacuum and closed. If the seal is broken (for example, during transportation or due to defects), sterility is lost instantly. Microorganisms quickly develop in such blood, making it toxic. Visual color inspection: normal blood is dark cherry in color. If it turns brown or acquires a purple hue, the process of decay has begun.
It is also worth considering the “age” of the donor and the initial state of the blood. Blood cells taken from a patient with infection or inflammation may degrade more quickly due to high white blood cell and enzyme activity. Therefore, for storing and creating reserves, blood is used only from healthy donors who have undergone strict selection.
☑️ Criteria for the suitability of blood for storage
Frequently asked questions (FAQ)
Is it possible to store blood at home refrigerator?
Absolutely not. Household refrigerators do not provide stable temperatures within a narrow range of +4 ± 2 °C. In addition, they do not have a constant mixing system (for platelets) and deep-freezing conditions of -30 °C (for plasma). Violation of the regime will make the blood unusable or dangerous.
What happens to the blood after the expiration date?
After the expiration date, red blood cells undergo hemolysis, toxic metabolic products accumulate in the plasma, and coagulation factors are destroyed. The use of such material can cause severe reactions in the patient, even death, so expired blood must be disposed of.
How to transport blood correctly if it takes a long time to get to the laboratory?
For transportation, special thermal containers with refrigerants (cold elements) are used, which maintain a temperature of +2...+8 °C for 24–48 hours. The tubes must stand vertically to avoid contact of blood with the stopper and possible hemolysis.
Does shelf life depend on blood type?
From the point of view of biochemistry and preservation, blood type (A, B, AB, 0) and Rh factor do not affect shelf life in the refrigerator. All red blood cells are stored for the same amount of time. Differences can only be in cryopreservation methods for rare phenotypes.