Compatibility Testing in Blood Transfusion - Part 3

Compatibility Testing: Special Considerations and Case Studies

Overview of Compatibility Testing

  • Compatibility testing is crucial in transfusion medicine, typically involving the following standard procedures:

    • Blood type determination (ABO and Rh).

    • Antibody screening.

    • Crossmatching if no clinically significant antibodies or relevant history exist.

Special Considerations in Transfusion Medicine

  • Certain circumstances may require additional considerations beyond standard compatibility testing.

Emergency Release of Blood Products

  • Emergency Release: In critical situations where there is an urgent need for blood transfusion before completing compatibility testing:

    • Typically required for trauma victims or during unforeseen surgical emergencies.

    • In such cases, O negative blood is often administered if there's no blood type available.

    • A form must be filled out by the physician assuming responsibility for potential transfusion reactions.

    • Blood units are labeled with a bright red sticker indicating they are uncrossmatched.

    • Segments (pigtails) are saved for later testing after the initial transfusion.

Massive Transfusion Protocol

  • Massive Transfusion: Defined as the transfusion of total volume equal to or exceeding the patient's blood volume, approximately 10 to 12 units in the average adult male.

    • Involves administering 8 to 10 units of packed red blood cells within 24 hours.

    • Protocols vary by facility but typically advocate a one-to-one-to-one ratio of red cells, plasma, and platelets to maintain hemostatic balance.

    • Essentials often include:

    • 4 to 6 units of packed red blood cells.

    • 4 to 6 units of thawed fresh frozen plasma.

    • 1 unit of apheresis platelets.

    • **Considerations: **

    • Platelet shelf life is limited to 5 days, posing a risk of bacterial growth if extended.

    • Thawed plasma effective for only 24 hours after preparation.

    • Risks of citrate toxicity and hyperkalemia due to storage of blood products.

    • Hypothermia risks when administering cold blood products.

Whole Blood Use

  • Whole blood is being reconsidered as an alternative to component therapy, particularly in massive transfusion situations:

    • Benefits include:

    • Longer shelf-life compared to separate components.

    • Greater levels of coagulants and functional platelets.

    • Reduces exposure to multiple donors.

    • Historically used in military settings; emerging data suggests improved outcomes compared to standard component therapy (i.e., separate red cells, plasma, and platelets).

Neonatal Transfusions

  • Special considerations when transfusing infants:

    • Only forward typing (ABO) is typically performed; reverse typing is avoided to prevent misinterpretation of maternal antibodies.

    • Blood for infants often requires special handling:

    • Only small volumes are transfused, typically about 25 mL.

    • To minimize wastage, blood may be delivered via syringe for transfusion.

    • Intrauterine Transfusions: For severe fetal anemia cases, which are invasive procedures involving the transfer of blood into the umbilical vein.

    • Typically employ O negative leukocyte reduced, packed red cells.

    • Blood units must be CMV-negative, irradiated to prevent graft-versus-host disease, and less than 7 days old to avoid storage-related complications.

    • Important to ensure blood is compatible with maternal antibodies present.

Transfusion Process and Post-Testing Procedures

  • Blood Release Procedures: Strict protocols govern the release of blood:

    • Donor unit labels must contain complete patient information.

    • Crosschecking between nurse and blood bank technologist is mandatory.

    • Vital signs (blood pressure, temperature, pulse) are monitored:

    • Before transfusion, 15 minutes after, and 30-45 minutes post-transfusion.

    • Post-transfusion testing is essential for adverse reaction management:

    • Hemoglobin-Hematocrit checks following transfusion to confirm efficacy.

Case Studies

Case Study 1:

  • Patient Profile: 62-year-old female with hemoglobin of 5.

    • Blood type: B positive.

    • Antibody Screen: Negative.

    • Possible Units: B+ (compatible), B- (compatible), O+ (compatible), O- (compatible).

    • Crossmatch Results: Immediate spin crossmatch indicates no agglutination (compatible).

Case Study 2:

  • Patient Profile: 58-year-old male with AML.

    • Blood type: A negative.

    • Antibody Screening: Positive (agglutination).

    • Identified Antibody: Anti-Kell.

    • Possible Units: A- (antigen negative for Kell), O- (antigen negative for Kell).

    • Crossmatch Results: Anti-globulin crossmatch yielded no reactions (compatible).

Case Study 3:

  • Patient Profile: 12-year-old female with sickle cell anemia.

    • Blood type: O positive.

    • Antibody Screen: Negative.

    • Crossmatch: Immediate spin indicates 159357 as incompatible (because the wrong unit may have been selected).

    • 268249 - (O positive) compatible.

Case Study 4:

  • Patient Profile: Artie Choke - emergency room bleeding case, on Coumadin.

    • Prothrombin Time (PT): 49.8 seconds, INR: 5.1 (indicating high bleeding risk).

    • Blood type: AB negative.

    • Plasma Requirement: AB plasma safe for transfusion.

    • Crossmatch: No crossmatch required for FFP or platelets, only for packed red blood cells.

Conclusion

  • Compatibility testing in transfusion medicine is critical to prevent adverse reactions and ensure patient safety. Various special considerations apply based on patient needs and clinical scenarios. Understanding these protocols is essential for effective practice in blood banks and for handling complex transfusion cases.