Blood plasma is the yellowish liquid component of blood that remains after red cells, white cells, and platelets are removed. It comprises about 55% of the total blood volume and contains water, proteins, hormones, and clotting factors. Because plasma is a biological product rich in complex proteins, its function relies on strict storage protocols. These protocols preserve its integrity before it is used in a patient.
Maximum Shelf Life for Frozen Plasma
Long-term storage of plasma requires deep freezing to halt protein decay. Fresh Frozen Plasma (FFP) is the standard product, prepared by separating the liquid component from whole blood and freezing it at -18°C or colder within eight hours of collection. This rapid freezing ensures maximum retention of all coagulation factors, giving FFP a shelf life of one year from the date of collection.
Storage duration can be extended using ultra-low temperatures. Storing plasma at -65°C or lower is recognized by regulatory standards to extend the viable shelf life up to seven years. This ultra-cold storage provides a large reserve that can be stockpiled for future needs.
Storage Limits After Thawing
The strict time limits change once frozen plasma is thawed, moving from a multi-year shelf life to a matter of hours. The thawing process involves placing the frozen unit into a controlled system until it reaches a temperature between 1°C and 6°C. Once thawed, the plasma is immediately refrigerated to slow degradation.
If the plasma is intended to maintain the highest levels of all original clotting proteins, it must be transfused within 24 hours of thawing while stored at 1°C to 6°C. After this 24-hour window, the product is relabeled as “Thawed Plasma” because some fragile proteins begin to lose potency. Thawed Plasma can then be stored under refrigeration for a total of up to five days (120 hours) from the time of thawing.
Varied Timelines for Specialized Plasma
While FFP sets the standard, other plasma products are prepared differently but adhere to the same frozen timeline. Plasma Frozen Within 24 Hours (PF24) is an alternative derived from whole blood that was not frozen until the 24-hour mark. Because of this extended processing time, PF24 has slightly lower levels of time-sensitive coagulation factors, such as Factor V and Factor VIII.
Despite the difference in initial factor concentration, PF24 is frozen at -18°C or colder and maintains the standard 1-year frozen shelf life. Another variation is Pathogen-Reduced Plasma (PRP), which undergoes an extra process to inactivate potential viruses and bacteria. PRP’s maximum frozen storage duration also aligns with the standard 1-year limit.
The Biological Rationale for Strict Time Limits
The strict expiration timelines, especially once plasma is thawed, rest on two scientific principles: protein degradation and microbial risk. The primary concern is the stability of labile clotting factors, particularly Factor V and Factor VIII. These factors degrade rapidly once the plasma is removed from its deep-frozen state, justifying the initial 24-hour limit for maintaining full potency.
The secondary concern is the risk of bacterial proliferation. Any biological product stored at refrigeration temperatures (1°C to 6°C) is susceptible to the growth of cold-tolerant bacteria. The maximum 5-day limit for Thawed Plasma safeguards against potential microbial contamination introduced during collection or thawing, ensuring the plasma remains safe for transfusion.