Questions
2 questions in professional theory papers
Difficulty
Medium
Importance
Essential for BMLT and MBBS clinical pathology exams
Overview
Blood component preparation is the process of separating whole blood into specific therapeutic fractions like red cells, plasma, and platelets. Mastering this is crucial for clinical diagnostics and transfusion medicine, as it ensures optimal treatment for patients with specific deficiencies rather than relying solely on whole blood transfusions.
Principles of Centrifugation
The separation of blood components relies on the differential sedimentation rates of cellular elements based on their specific gravity. By using controlled centrifugal force, blood is fractionated into layers that can be systematically extracted.
- Light spin for Platelet-Rich Plasma (PRP) separation
- Heavy spin for Red Cell Concentrates
- Specific gravity of RBCs > WBCs > Platelets > Plasma
- Temperature control (20-24°C for platelets) is vital during spin
Red Blood Cell Concentrates (PRBC)
PRBCs are prepared by removing the majority of plasma from whole blood, leaving a high concentration of erythrocytes. This component is essential for managing severe anemia while minimizing circulatory overload.
- Storage temperature: 2°C to 6°C
- Shelf life: 35 days (CPDA-1) or 42 days (additive solutions like SAGM)
- Hematocrit should ideally be 50-70%
- Primary indication: Symptomatic anemia
Platelet Concentrates
Platelets are prepared either via buffy coat method or apheresis to treat thrombocytopenia or prevent hemorrhage. They are highly sensitive to temperature and agitation to maintain viability.
- Storage temperature: 20°C to 24°C
- Continuous gentle agitation is mandatory
- Shelf life: 5 days
- Must be stored in gas-permeable containers
Fresh Frozen Plasma (FFP)
FFP is prepared by separating plasma from whole blood and freezing it at extremely low temperatures within hours of collection. It contains all coagulation factors and is used to correct coagulation factor deficiencies.
- Storage temperature: -30°C or colder
- Shelf life: 1 year
- Must be thawed in a water bath at 30°C to 37°C
- Rich in Factor V, Factor VIII, and fibrinogen
Formula Sheet
RCF (Relative Centrifugal Force) = 1.118 x 10^-5 x radius x (RPM)^2
Exam Tip
Always link the storage temperature of a component directly to the metabolic requirement and shelf life, as this is the most frequently tested aspect in board exams.
Common Mistakes
- Confusing the storage temperatures of RBCs (refrigerated) versus Platelets (room temperature).
- Failing to mention the necessity of continuous agitation for platelet storage.
- Incorrectly stating that FFP contains only albumin; it contains all labile coagulation factors.
More Revision Notes
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