Chapter 10

1. Chapter 10 Pretransfusion Testing

2. Introduction • Transfused red blood cells (RBCs) should have an acceptable survival rate, and there should not be significant destruction of the recipient’s own RBCs. • Strict adherence to and application of each parameter of pretransfusion testing is imperative to the management of safe blood transfusion therapy.

3. Testing Standards • A major cause of transfusion-associated fatalities is clerical error resulting in incorrect ABO groupings and transfusion of ABO incompatible blood.

4. Positive Recipient Identification • The most common cause of error is misidentification of the recipient. • Exact procedures for proper identification of the recipient, recipient sample, and donor unit must be established and utilized by all staff responsible for each aspect of transfusion therapy.

5. Collection of Patient Samples • Serum or plasma may be used for pretransfusion testing. • Advantages/disadvantages with use of plasma • Tubes must be labeled before they leave the recipient’s bedside. • Use of imprinted labels and proper patient ID • Confirmation of information on the sample and requisition form within the blood bank • Patient RBCs can be obtained from either clotted or anticoagulated samples.

6. Collection of Donor Samples • Samples for donor testing must be collected at the same time as the full donor unit. • Clotted and/or anticoagulated pilot samples are obtained per the testing methods in use. • Proper use of donor unit identification number. • RBCs for donor pretransfusion testing can be prepared from the segmented tubing through which the donor blood was collected.

7. Testing the Donor Sample • ABO grouping and Rh typing (including a test for weak D) and tests intended to prevent disease transmission must be performed. • Required screening for unexpected antibodies • Required confirmatory testing at the transfusing facility • Required standards for reagents used in testing

8. Testing the Patient Sample • A record must be maintained of all results obtained in testing patient samples. • ABO, Rh, and unexpected antibody screening • Unusual serologic reactions and the identity of unexpected antibodies in the patient’s serum should also be included in the record.

9. Selection of Appropriate Donor Units • The first choice for transfusion is blood and components of the patient’s own ABO and Rh. • If ABO group-specific blood is not available or is in less than adequate supply, alternative blood groups are chosen. • Use of Rh-negative blood • Use of antigen-negative donor units when unexpected antibodies are present • Visual inspection of donor units

10. Crossmatch Testing • The crossmatch test has traditionally meant the testing of the patient’s serum with the donor RBCs including an antiglobulin phase or simply an immediate spin phase to confirm ABO compatibility.

11. Purposes of the Serologic Crossmatch • It is a final check of ABO compatibility between donor and patient. • It may detect an antibody in the patient’s serum that will react withantigens on the donor RBCs but was not detected in antibody screening (corresponding antigen was lacking from the screening cells).

12. Crossmatch Testing (cont’d) • Crossmatch methods can generally be categorized by the test phase in which the procedure ends. • Immediate Spin Crossmatch • Advantages, disadvantages, ideal purposes • Antiglobulin Crossmatch • Advantages, disadvantages, ideal purposes • AABB Standards requirements

13. Interpretation of Results • Tube and Gel Card results must be read according to the Blood Bank’s SOP. • According to the Code of Federal Regulations,all results must be recorded immediately in a permanent ledger by means of a logical system that allows them to be easily recalled. • Actual observations as well as interpretations must be recorded.

14. Resolution of Incompatibilities in the Serologic Crossmatch • The primary objective of the crossmatch test is to detect the presence of antibodies in the recipient’s serum, including anti-A and anti-B, that could destroy transfused RBCs. • Cause of incompatibility must be determined. • The autocontrol and antibody screening test results should be reviewed.

15. Causes of Positive Results in the Serologic Crossmatch • Incorrect ABO grouping of the patient or donor • An alloantibody in the patient’s serum reacting with the corresponding antigen on donor RBCs • An autoantibody in the patient’s serum reacting with the corresponding antigen on donor RBCs

16. Causes of Positive Results in the Serologic Crossmatch (cont’d) • Prior coating of the donor RBCs with protein, resulting in a positive antihuman globulin test • Abnormalities in the patient’s serum • Contaminants in the test system

17. Computer Crossmatch • The computer crossmatch compares recent ABO serologic results and interpretations on file for both the donor and the recipient being matched and determines compatibility based on this comparison.

18. Emergencies • The recipient may require transfusion of RBC components before pretransfusion testing is completed. • Must proceed by an established protocol. • Adequate pretransfusion samples necessary. • Patient’s ABO and Rh group should be determined. • Accurate records must be kept. • Patient’s physician must authorize.

19. Transfusion of Non-Group-Specific Blood • When donor units of an ABO group other than the recipient’s own type have been transfused, testing the recipient’s serum in a freshly drawn sample for the presence of unexpected anti-A and/or anti-B must be performed prior to giving any additional RBC transfusions.

20. Compatibility Testing for Transfusion of Plasma Products • Compatibility testing procedures are not required for transfusion of plasma products. • For transfusion of large volumes of plasma and plasma products, a crossmatch test between the donor plasma and patient RBCs may be performed, although current Standards do not require a crossmatch test.

21. Intrauterine Transfusions • Blood for intrauterine transfusion must be compatible with maternal antibodies capable of crossing the placenta. • Fetal ABO and Rh known/not known situations for group specific/group O Rh negative products • Check for maternal antibodies/donor antigens. • No fetomaternal ABO or Rh incompatibility • Crossmatch testing is performed using the mother’s serum sample.

22. Neonatal Transfusions • Blood for an exchange or regular transfusion of a neonate (younger than 4 months of age) should be compatible with any maternal antibodies that have entered the infant’s circulation and are reactive at 37°C or AHG. • ABO and Rh testing required. • Antibody detection testing required. • Blood should be as fresh as possible, not older than 7 days.

23. Massive Transfusions • The administration of 8 to 10 RBC units to an adult patient in less than 24 hours.OR • The acute administration of 4 to 5 RBC units in 1 hour (AABB Technical Manual). • Use antigen negative units for patient with known antibodies if possible. • Physician must sign a waiver of testing or a release form for all untested units for transfusion.

24. Preoperative Autologous Blood • Pretransfusion testing and identification of the recipient and the blood sample are required and must conform to the protocols mentioned for autologous blood. • Tests for unexpected antibodies in the recipient sample and a crossmatch test are optional. • These units must be labeled “For autologous use only.”

25. Limitations of Compatibility Testing Procedures • No current testing procedure can guarantee the fate of a unit of blood that is transfused. • Even a compatible crossmatch cannot guarantee that the transfused RBCs will survive normally in the recipient.

26. Blood Inventory Management • The Maximum Surgical Blood Ordering Schedule (MSBOS) was developed to promote more efficient utilization of blood and to establish realistic blood ordering levels for certain procedures. • Utilization of a Type and Screen policy, along with MSBOS, may enhance the effectiveness of the blood inventory management program.

27. Reidentification of the Patient Before Transfusion • The same approach used to properly identify the patient before sample collection must now be applied to verify that the recipient is indeed the same person who provided the initial blood sample for testing.

28. Reidentification of the Patient Before Transfusion (cont’d) • The actual product and accompanying record of testing must be verified as relating to the same donor unit number. • The bedside check just prior to blood administration is the most critical step for prevention of mistransfusion.

29. Reidentification of the Patient Before Transfusion (cont’d) • A statement of compatibility must be retained as part of the patient’s permanent medical record if the blood is transfused. • A label or tie tag must be attached to the unit stating the identity of the intended recipient, the results of pretransfusion testing, and the donor unit number.

30. Reidentification of the Patient Before Transfusion (cont’d) • Machine-readable, especially barcode patient-blood unit identification, is ideally suited to bedside check requirements and has been recently reported to significantly improve transfusion practice. • Use of radio frequency identification devices (RFID) to improve identification at every stage of pretransfusion testing.

31. Reidentification of the Patient Before Transfusion (cont’d) • Whatever system is used, the information should be verified at least twice before the transfusion of the blood product. • Before blood is taken from the blood bank to the patient treatment area, check • ABO and Rh results • Clinically significant unexpected antibodies • Adverse reactions to transfusion

32. Reidentification of the Patient Before Transfusion (cont’d) • Before transfusion is initiated, a reliable professional (and preferably two professionals) must once again verify identity of the patient and donor products. • A system of positive patient identification by comparison of wristband identification and compatibility forms must be followed strictly.