Fresh frozen plasma (FFP) is the liquid portion of donated blood, separated from red blood cells and platelets, then frozen within eight hours of collection. It contains all of the blood’s clotting factors, a range of proteins that help regulate bleeding and immunity, and electrolytes suspended in water. A single unit is typically 200 to 250 milliliters, roughly the volume of a small juice box.
Clotting Factors: The Primary Contents
The main reason FFP exists as a medical product is its clotting factors. It contains about 1 international unit per milliliter of each coagulation factor, including the so-called “labile” factors (Factor V and Factor VIII) that degrade quickly outside the body. Freezing the plasma rapidly after collection is what preserves these fragile proteins.
A standard unit delivers all 13 clotting factors needed for the coagulation cascade, the chain reaction your body uses to form blood clots and stop bleeding. It also contains 400 to 900 milligrams of fibrinogen per unit, the protein that forms the mesh-like structure of a clot. This makes FFP useful when someone’s clotting system is compromised across the board, rather than deficient in just one specific factor.
Natural Anticoagulants and Regulatory Proteins
Plasma doesn’t just help blood clot. It also carries proteins that prevent excessive clotting. FFP contains protein C, protein S, antithrombin, and tissue factor pathway inhibitors. These act as a counterbalance, keeping the clotting system in check so it activates only when and where it’s needed. Without them, clots could form uncontrollably throughout the bloodstream.
Albumin, the most abundant protein in blood plasma, is also present. Albumin helps maintain fluid balance by keeping water inside blood vessels rather than leaking into surrounding tissues. It also serves as a transport molecule, carrying hormones, vitamins, and other substances through the bloodstream.
Electrolytes and Additives
Beyond proteins, FFP contains electrolytes at concentrations that reflect both the donor’s blood and the anticoagulant solution added during collection. Sodium levels run around 167 mEq/L on average, which is higher than normal blood levels (typically 136 to 145 mEq/L). Potassium sits lower, around 1.6 to 1.8 mEq/L. The osmolarity, a measure of how concentrated the solution is, averages about 367 mOsm/L.
The anticoagulant mixed in during collection is citrate phosphate dextrose (CPD). Citrate works by binding calcium in the plasma, which prevents the blood from clotting inside the collection bag. Dextrose, a simple sugar, provides a nutrient source that helps preserve the product. These additives are the reason FFP’s sodium and sugar levels differ from what you’d measure in a fresh blood draw.
What FFP Does Not Contain
FFP has no red blood cells, no white blood cells (in significant numbers), and no platelets. It is purely the fluid portion of blood with its dissolved proteins and electrolytes. This means it cannot carry oxygen, fight infections, or help with platelet-related bleeding problems. For those functions, other blood products like packed red blood cells or platelet concentrates are used separately.
How It’s Stored and Handled
Under federal regulations, FFP must be frozen at minus 18°C (about 0°F) or colder within eight hours of collection. At that temperature, it can be stored for up to one year. The rapid freeze is critical because it locks clotting factors in their active form. Factor VIII, for example, loses potency quickly at room temperature but remains stable once frozen.
Once thawed for use, the clock starts ticking. Thawed plasma is typically kept refrigerated and used within 24 hours, since the labile clotting factors begin to degrade. Storage facilities must either continuously monitor temperature or store units in a way that would reveal any accidental thawing, such as visible changes in the bag’s appearance.
Blood Type Compatibility
Unlike red blood cell transfusions, where type O is the universal donor, plasma compatibility works in reverse. Type AB plasma is the universal donor for plasma transfusions because it contains no anti-A or anti-B antibodies that could attack the recipient’s red blood cells. When AB plasma isn’t available, the plasma should match the recipient’s ABO blood type to avoid a reaction.
Risks of FFP Transfusion
FFP is generally well tolerated, but it carries measurable risks. Allergic reactions are the most common, occurring at a rate of about 92 per 100,000 units transfused. These range from mild hives and itching to more serious anaphylactic responses. Transfusion-associated circulatory overload (TACO), where the added fluid volume strains the heart and lungs, occurs in roughly 6 per 100,000 units. Transfusion-related acute lung injury (TRALI), a more serious inflammatory reaction in the lungs, is rarer at about 1.8 per 100,000 units but can be life-threatening.
The volume of FFP itself contributes to these risks. Each unit adds 200 to 250 mL of fluid to the circulation, and patients often receive multiple units. For someone with heart failure or kidney problems, that extra fluid can tip the balance toward overload even when the plasma contents are exactly what’s needed.