Overview
Donated blood can either be transfused as whole blood or separated into individual components — packed red cells, platelet concentrate, fresh frozen plasma and cryoprecipitate. Component separation maximizes the clinical yield of every donation, allows the optimal product to be given for a specific disease, and minimizes the recipient's exposure to unnecessary blood components.
This lesson also introduces hemapheresis, a technique for selectively harvesting one blood component from a donor while returning the rest to circulation.
Learning Objectives
After this lesson you will be able to…- Describe the different blood components and their clinical uses.
- Discuss the production of blood components from whole blood.
- Explain the selection of appropriate blood components for specific clinical conditions.
- Describe hemapheresis and its clinical applications.
- State the storage conditions and shelf life of each blood component.
Clinical Story
Why This MattersA patient with chronic anemia from renal failure needs correction of hemoglobin without volume overload. The blood bank technologist correctly selects packed red cells instead of whole blood — concentrating the therapeutic red cell mass while avoiding the excess plasma volume that could precipitate heart failure in this fragile patient.
Core Concepts
Separating blood into components maximizes the yield of products from a single donation, allows the optimal product to be used for a specific disease, and reduces the recipient's exposure to unnecessary foreign material. Common components: whole blood, packed cells, platelet concentrate, fresh frozen plasma (FFP), and cryoprecipitate. Others include leukodepleted packed cells, platelet-rich plasma, platelet-poor plasma, and fresh plasma.
Whole blood: 450 mL collected with 63 mL of CPD or CPDA-1 anticoagulant; stored 1–6°C for 21–35 days; used in blood loss anemia (e.g. trauma). Packed red cells: plasma removed to raise hematocrit to 70–80%; an additional 100mL storage solution (e.g. CPD) extends storage to 42 days; indicated for chronic anemia where hemoglobin — not blood volume — is deficient.
Platelet concentrates: produced within 8 hours of collection; stored at room temperature (20–24°C) for up to 5 days; pH must stay ≥6 for functionality; each unit contains a minimum of 5.5×10¹⁰ platelets; used to prevent bleeding from thrombocytopenia. Fresh Frozen Plasma (FFP): 200–260mL obtained by light spin, frozen to ≤-18°C within 8 hours of collection; rich source of plasma proteins and coagulation factors; used for coagulation factor deficiencies and DIC.
Blood collected for component production uses special bags with 2–3 attached satellite bags. Components are separated in refrigerated centrifuges using a light or heavy spin depending on the desired product. Platelet concentrate preparation uses room temperature centrifugation (20–24°C); all other components are centrifuged between 1°C and 6°C.
Blood is withdrawn from the donor, anticoagulated, and the desired component separated; remaining blood is returned to the donor. Platelet apheresis is the most common application, collecting a high-yield platelet dose from a single donor while returning red cells and plasma.
Laboratory Principle
Blood component separation relies on differential centrifugal sedimentation — red cells, being densest, settle first with a light spin (leaving platelet-rich plasma above), while a heavy spin further separates platelets from plasma. Refrigerated centrifugation preserves labile coagulation factors and cellular integrity, whereas room-temperature centrifugation is required for platelets to remain metabolically functional.
Equipment Required
Reagents & Materials
| Reagent / Material | Concentration / Grade | Purpose | Storage |
|---|---|---|---|
| CPD (Citrate Phosphate Dextrose) | 63 mL per 450 mL blood | Anticoagulant/preservative for whole blood | Room temperature (in collection bag) |
| CPDA-1 | Standard formulation | Extended anticoagulant/preservative | Room temperature (in collection bag) |
| Additional storage solution | 100 mL | Added to packed cells to extend storage to 42 days | Added post-centrifugation |
Step-by-Step Procedure
Collect 450 mL of donor blood into a multi-bag system containing 63 mL CPD or CPDA-1 anticoagulant.
Centrifuge at light spin (e.g. 2000g for 3 min) to separate platelet-rich plasma (PRP) from packed cells.
Express PRP into a satellite bag; further heavy-spin the PRP (5000g for 5 min) to separate platelet concentrate from platelet-poor plasma.
Freeze plasma within 8 hours to -18°C or below to make FFP; alternatively thaw FFP slowly at 4°C to prepare cryoprecipitate from the cryo-insoluble fraction.
Label each component with donor ID, blood group, expiry date and store at the appropriate temperature per component type.
Flow Diagram
Quality Control
Regularly verify platelet concentrate pH stays at or above 6 throughout storage, and confirm each unit contains the minimum 5.5×10¹⁰ platelets. Monitor storage refrigerator/freezer temperatures continuously with alarm systems.
Blood banks should participate in accreditation programs that periodically audit component preparation techniques, storage conditions and component potency testing.
Reference Values
Normal Ranges⚠️ Reference ranges may vary between laboratories. Always apply your laboratory's established reference intervals.
Clinical Interpretation
| Clinical Scenario | Appropriate Component | Rationale |
|---|---|---|
| Acute blood loss (trauma) | Whole blood | Replaces both volume and oxygen-carrying capacity |
| Chronic anemia without volume loss | Packed red cells | Corrects hemoglobin without volume overload |
| Bleeding from thrombocytopenia | Platelet concentrate | Directly replaces deficient platelets |
| Coagulation factor deficiency / DIC | Fresh Frozen Plasma | Rich source of clotting factors and plasma proteins |
Common Errors & How to Avoid Them
Cause: Using whole blood when only red cell mass is deficient, risking volume overload.
Prevention: Select packed red cells for chronic anemia without active blood loss.
Cause: Cold storage impairs platelet function and viability.
Prevention: Always store platelet concentrates at room temperature (20–24°C) with gentle continuous agitation.
Cause: Labile coagulation factors (V and VIII) degrade if plasma is not frozen promptly.
Prevention: Freeze plasma to -18°C or below within 8 hours of collection to preserve FFP quality.
Laboratory Tips from the Bench
Always match the component to the specific deficiency — this reduces unnecessary exposure to foreign blood components and associated transfusion risks.
Remember platelet concentrates are the only blood component stored at room temperature — everything else needs refrigeration or freezing.
"Platelets like it warm, plasma likes it frozen" — helps recall the differing storage requirements of each component.
Important Notes
Giving only the specific component a patient needs — rather than whole blood — reduces exposure to unnecessary donor antigens and proteins, lowering transfusion reaction risk.
A single apheresis donor can provide a therapeutic platelet dose equivalent to multiple whole blood donations, reducing recipient exposure to multiple donors.
Interactive Quiz
Test Your KnowledgeFlashcards
Tap to flipClick or tap any card to reveal the answer.
Clinical Case Study
Apply Your KnowledgePresents with fatigue and shortness of breath on exertion. No active bleeding. Hemoglobin found to be 6.8 g/dL on routine check, stable renal function otherwise.
Chronic anemia from renal disease without active blood loss requires correction of hemoglobin without adding unnecessary plasma volume, which could risk fluid overload in a CKD patient.
- →Packed red cells avoid unnecessary volume load in chronic anemia.
- →Whole blood is reserved for situations with concurrent volume loss (e.g. trauma).
- →Component selection should always match the specific clinical deficiency.
Frequently Asked Questions
Continuous gentle agitation prevents platelet clumping and maintains gas exchange, both of which are essential to preserving platelet viability and function during the 5-day storage period.
Component therapy allows precise treatment of the specific deficiency (red cells, platelets, or clotting factors) while minimizing unnecessary exposure to other blood constituents, reducing transfusion reaction risk and maximizing the number of patients helped per donation.
A single apheresis platelet donation can provide a full therapeutic platelet dose from one donor, reducing the recipient's exposure to multiple donors compared to pooling platelets from several whole blood donations.
Quick Revision
10-Minute ReviewKey Takeaways
- Blood components include whole blood, packed cells, platelet concentrate, FFP and cryoprecipitate.
- Component separation maximizes donation yield and reduces unnecessary recipient exposure.
- Each component has distinct storage temperature, shelf life and clinical indication.
- Whole blood suits acute blood loss; packed cells suit chronic anemia.
- Platelet concentrates require room-temperature storage; FFP requires freezing.
- Hemapheresis enables efficient single-donor component collection, especially for platelets.
Competency Checklist
Track Your MasteryReferences
- NIOS Hematology and Blood Bank Technique — Lesson 27: Blood Components.
- WHO. Blood Transfusion Safety — Manual on the Management, Maintenance and Use of Blood Cold Chain Equipment.