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Blood Bank

Reagents

Just like having a properly identified patient sample is crucial, ensuring the Reagents we use to test that sample are working perfectly is absolutely fundamental. Faulty reagents lead to faulty results, and that’s something we absolutely cannot afford in the blood bank!

Think of reagents as our highly specialized tools – our Anti-A, Anti-D, Screening Cells, AHG, etc. QA ensures these tools are sharp, accurate, and reliable every single time we use them. It’s a continuous process governed by strict standards (like those from AABB, CAP, FDA)

Here’s a breakdown of the key QA aspects for blood bank reagents:

Receiving, Inspection, and New Lot Validation

  • Verification Upon Arrival
    • Check the shipping conditions. Were temperature-sensitive reagents shipped appropriately (e.g., refrigerated)?
    • Verify the shipment against the packing slip and purchase order. Did we get what we ordered? Correct reagent, correct number of vials?
    • Inspect packaging for damage, leakage, or compromised seals
    • Check Lot Numbers and Expiration Dates. Ensure adequate shelf life remains
  • Documentation: Log the date received, reagent name, manufacturer, lot number, expiration date, and condition upon arrival
  • New Lot / New Shipment Validation (CRITICAL!): Before a new lot number (or sometimes even a new shipment of an existing lot) can be put into routine use, it MUST be tested in parallel with the current, in-use lot number
    • Purpose: To confirm the new lot performs comparably to the old lot and meets sensitivity/specificity requirements. Catches potential manufacturing issues or damage during shipping
    • How: Test both new and old lots against known positive and negative control cells/sera. Results should be consistent and meet expected reactivity criteria. Document this validation thoroughly

Storage: Maintaining Stability

  • Temperature is Key: Most blood bank reagents require refrigeration (1-6°C). Some may need freezing or room temperature storage
    • Monitoring: Refrigerators/freezers MUST be continuously monitored with calibrated thermometers and alarm systems. Temperatures must be checked and recorded daily (manually or via electronic system)
    • Placement: Store reagents according to manufacturer’s instructions (e.g., upright, protected from light if necessary). Don’t overcrowd shelves (allow air circulation). Don’t store in doors where temperatures fluctuate more
  • Organization: Store reagents logically to prevent mix-ups (e.g., separate different antisera clearly). Be mindful of look-alike/sound-alike vials
  • Prevent Contamination: Use aseptic technique when opening and handling vials. Don’t interchange dropper caps

Daily Quality Control (QC): The Routine Check-Up

This is the cornerstone of daily reagent QA – confirming that reagents are performing as expected on the day of use

  • Purpose: Detects any deterioration, contamination, or loss of potency that may have occurred since the last use or validation
  • Frequency: Performed each day of use before any patient testing. Some methods might require QC per run
  • Method: Test the reagent against cells or plasma with known antigen/antibody profiles (positive and negative controls)
  • Specific QC Examples
    • Blood Grouping Sera (Anti-A, Anti-B, Anti-D, etc.): Test against known A, B, O, Rh(D)+, and Rh(D)- cells. Must show expected positive reactions (with appropriate strength) and clear negative reactions. Specificity and potency are checked. The Rh control reagent must always be tested alongside Anti-D and must be negative
    • Reagent Red Blood Cells (Screening Cells, Panel Cells, A1/B Cells): Test with known positive sera (e.g., weak anti-D for screening cells) and negative sera/saline. Must show expected reactivity and lack of spontaneous agglutination or hemolysis. Visual inspection for hemolysis in the vial is also important
    • Antiglobulin Sera (AHG - Polyspecific, Anti-IgG, Anti-C3d): Test against known IgG-sensitized cells (like commercial Check Cells or lab-prepared sensitized cells) and unsensitized cells. Must agglutinate the sensitized cells and show no reaction with unsensitized cells. Check Cells are also used to validate negative IAT/DAT results
    • Lectins (Anti-A1, Anti-H): Test against known positive (e.g., A1 cells for Anti-A1) and negative (e.g., A2 cells for Anti-A1) cells
  • Interpretation: Results MUST fall within the laboratory’s established acceptance criteria (e.g., minimum reaction grade for positives, clear negative for negatives)
  • Documentation: Record all QC results, interpretations (Pass/Fail), date, time, technologist initials, and reagent lot numbers/expiration dates

Documentation and Record Keeping

  • Comprehensive Logs: Maintain detailed records for everything: reagent receipt, validation, daily QC (including actual results, not just Pass/Fail), temperature monitoring, corrective actions, and disposal
  • Accessibility & Retention: Records must be organized, easily retrievable, and kept for the duration required by accrediting agencies (often years). Use standardized forms or LIS modules

Inventory Management

  • Track Usage: Monitor reagent usage to ensure adequate stock levels
  • Rotate Stock (FIFO): Use the “First-In, First-Out” principle. Place newer shipments behind older ones to use reagents with shorter expiration dates first
  • Discard Expired Reagents: Regularly check expiration dates and promptly discard any expired reagents according to safe disposal procedures. Never use expired reagents for clinical testing!

Troubleshooting QC Failures

  • STOP!: If any QC result fails, the reagent cannot be used for patient testing until the issue is resolved
  • Investigate: Follow a systematic approach:
    • Was it a procedural error? (Wrong sample, wrong reagent added?) Repeat the QC
    • Are the control cells/plasma suspect? Try different control materials
    • Is the equipment functioning correctly? (Centrifuge speed/timer, incubator temp?)
    • Try a new vial of the same reagent lot. Could be contamination/degradation of that specific vial
    • If still failing, try a vial from a different, validated lot number
  • Document: Record all troubleshooting steps, findings, and corrective actions taken
  • Notify: Inform supervisor/QA coordinator

Key Terms

  • Quality Control (QC): Procedures performed routinely (e.g., daily) to monitor the performance of reagents, equipment, and methods, ensuring they meet established criteria
  • Lot Number: A unique identifier assigned by the manufacturer to a specific batch of reagent produced at the same time under the same conditions
  • Expiration Date: The date after which a reagent should no longer be used, as its stability and reactivity cannot be guaranteed
  • Validation: The process of confirming that a new reagent lot, method, or piece of equipment performs as expected before being put into routine clinical use
  • Potency: The strength or reactivity level of a reagent (e.g., how strongly Anti-A agglutinates A cells)
  • Specificity: The ability of a reagent (e.g., antiserum) to react only with its intended target antigen and not with others
  • Positive Control: A material known to contain the substance being tested for, used to confirm that the test system can detect a positive result
  • Negative Control: A material known to lack the substance being tested for, used to confirm the specificity of the test system and rule out false positives
  • Parallel Testing: Testing a new reagent lot or method simultaneously with the current, established lot or method using the same control materials for comparison
  • FIFO (First-In, First-Out): Inventory management principle ensuring that older stock is used before newer stock to minimize waste due to expiration