Chapter 11

1. Chapter 11 Overview of the Modern Blood Bank Laboratory

2. Organization • Blood bank laboratory: a facility involved in the collection, storage, processing, and distribution of human blood and blood products for transfusion. • Usually functions as a unit of a larger organization • Regulating agency: Food and Drug Administration (FDA) • Accrediting organization: usually the American Association of Blood Banks (AABB)

3. Blood Banks With Collection Facilities • Blood resources may be used more efficiently by separating them into a variety of components. • After collection, whole blood is allowed to cool to room temperature (20°C to 24°C) if platelets are to be prepared from the unit. • Whole blood may be cooled to 1°C to 10°C if the unit is to be processed for frozen plasma.

4. Blood Banks With Collection Facilities (cont’d) • Fresh frozen plasma (FFP) must be prepared within 8 hours of collection of the whole blood unit. • FP24 may be prepared up to 24 hours following collection of the whole blood unit. • Platelets may be prepared from whole blood stored at room temperature for up to 24 hours following collection of the whole blood unit.

5. Blood Banks With Collection Facilities (cont’d) • Frozen plasma can be further manipulated to yield cryoprecipitate. • Some blood components may also be prepared through a procedure known as apheresis.

6. Blood Banks Without Collection Facilities • Blood banks that depend on an outside source for their blood supplies usually receive their products in component form. • Platelet concentrates and cryoprecipitate may be received as individual units but are more easily administered if pooled before infusion. • Sterile connecting devices (STCDs) have also become commonplace in some blood banks.

7. Equipment Found in Most Blood Banks • Refrigerators maintained at 1°C to 6°C • Freezers maintained at –18°C or lower • Freezers maintained at –65°C or lower • Platelet rotators or flatbed agitators that provide constant gentle agitation at room temperature for the storage of apheresis and random donor platelets

8. Donor Processing • Tests must be performed at each donation regardless of the number of times a donor has previously donated. • Blood processing centers utilize the testing methods that will provide the safest blood product for patients.

9. Product Labeling • Labeling of blood products occurs only after a careful review of all test results, including • No discrepancies in the ABO and Rh testing • Absence of detectable antibodies in plasma-containing components • Nonreactive viral marker tests • Nonreactive syphilis test

10. Product Labeling (cont’d) • When the established criteria are met, the RBCs and any other components are labeled and stored at their proper temperatures. • Units received from outside sources would be tested completely and approved for transfusion.

11. Product Labeling (cont’d) • The blood bank to which this blood is shipped is required to reconfirm the labeled ABO of each RBC-containing product. • The Rh type of all Rh-negative units must be also be reconfirmed.

12. Main Laboratory • Testing determines the compatibility between a patient requiring transfusion and the unit of blood. • Pretransfusion testing protocols are established to ensure the orderly, timely, and accurate processing of patient.

13. Sample Collection and Acceptance • Proper patient identification is crucial for any specimen used in blood bank testing. • A minimum of two identifiers is required for patient samples used for blood bank testing. • The patient’s full name is required, as well as date of birth and/or medical record number. • The blood bank number is applied to the blood sample and is included in the record of any compatibility testing performed on that sample, as well as on any donor units transfused based on results from that sample.

14. Routine Testing • Once a patient sample has been judged acceptable, the testing requested by the patient’s physician can be performed. • Type and screen • Type and crossmatch • Prenatal evaluation • Postpartum evaluation • Cord blood studies

15. Type and Screen • Allows better utilization of blood supplies • ABO and Rh testing and antibody screening are performed. • The patient’s transfusion record is checked. • If an antibody is detected the antibody is identified, and compatible units are reserved for the patient.

16. Type and Crossmatch • Reserves completely tested and crossmatched blood for the patient • Routine and emergency crossmatches • Positive antibody screen: the antibody must be identified • Clinically significant antibody: antigen-negative units must be chosen for transfusion • Abbreviated crossmatch protocols • Electronic or computer crossmatch protocols

17. Prenatal Evaluation • Includesdetermination of the ABO group and Rh type of the mother and antibody screen for antibodies that have the potential to cause HDFN • Consideration of Weak D and Partial D testing • If the result of the antibody screen is positive, the antibody must be identified. • Serial titrations may be performed during the course of the pregnancy.

18. Postpartum Evaluation • All women admitted for delivery are required to be tested to determine their Rh status. • If the mother is Rh-negative and her baby is Rh-positive, the maternal sample is further evaluated to detect a fetomaternal hemorrhage (FMH). • Kleihauer-Betke test, flow cytometry, or enzyme-linked antiglobulin test for FMH >30 ml WB.

19. Cord Blood Studies • Protocols to evaluate cord blood specimens can vary widely from blood bank to blood bank. • Cord blood from infants born to Rh-negative mothers is tested for D and for weak D to determine the mother’s candidacy for RhIg. • ABO and Rh typing and Direct Antiglobulin Testing (DAT) are performed on cord samples from infants born to women with clinically significant antibodies.

20. Issue of Blood Products • Blood components may be released for transfusion to the designated recipient after pretransfusion testing is complete. • All serologic testing and discrepancies must be resolved before issue of blood products, except in extreme emergency. • Requirements for written requests and identification of patient and designated products.

21. Reference Laboratory • The problem-solving section of the transfusion service • Resolution of any discrepancies detected in routine testing • Include an investigation of the patient’s diagnosis, age, pregnancy, drug, and transfusion history

22. ABO Discrepancies • All inconsistencies between forward and reverse grouping must be resolved before an ABO interpretation can be made. • Testing with A2 cells or Anti-A1 lectin • Room temperature antibody identification • Adsorption, elution, and autoadsorption studies • Removal of RBC-bound cold autoantibodies • Secretor studies

23. Rh Discrepancies • Problems in Rh typing may occur because of certain clinical conditions or inherited characteristics. • Rh phenotyping • Adsorption and elution using Rh antisera • Isolation of cell populations • Use of rare antisera and RBCs

24. Antibody Identification • A positive antibody screen in the absence of a positive autocontrol or DAT result indicates possible alloantibody immunization by means of blood transfusion or pregnancy. • Antibody identification panels using various enhancement media • Antibody identification panels pretreated with reagents

25. Antibody Identification (cont’d) • Neutralization using such substances as plasma, saliva, urine, or human milk • Antigen typing • Titration • Adsorption and elution studies • Treatment of serum with DTT or 2-mercaptoethanol • Use of rare sera and cells

26. Positive DAT • May be the result of an immune reaction to a drug, a disease state, or a delayed hemolytic transfusion reaction • Use of monospecific reagents (anti-IgG, anti-C3) • Elution techniques and antibody identification • Reagent removal of cell-bound antibody • RBC phenotyping • Drug studies • Cell separation techniques

27. Warm Autoantibodies • May mask the presence of clinically significant alloantibodies • Removal of RBC-bound autoantibody followed by serum autoadsorption • Heterologous or differential serum adsorptions • Elution techniques • Autoantibody identification • Cell separation techniques

28. Cold Autoantibodies • May cause ABO discrepancies, a positive DAT, and may mask clinically significant alloantibodies • Removal of RBC-bound autoantibody using 37°C saline • Prewarmed technique • Autoadsorption • Treatment of serum or cells with DTT or 2-ME • Adsorption using rabbit erythrocyte stroma

29. Transfusion Reactions • Must be investigated to determine if the reaction is antibody-mediated • Initial studies including ABO, Rh, DAT, and visual check for hemolysis using a post-transfusion sample • Further investigation may be necessary

30. Personnel Requirements • Specified by The Clinical Laboratory Improvement Amendments of 1988 (CLIA ’88) • Subpart M of these regulations establishes personnel qualifications for laboratories performing certain types of testing • Blood bank laboratories are engaged in both moderately and highly complex testing • Requirements for written training procedures

31. Standard Operating Procedures (SOPs) • Manuals outlining the operations of the laboratory • Provide details on how, when, and why particular activities are done; procedures for all tests performed • Are integral components of any blood bank laboratory’s QA Program

32. Transfusion Process Oversight • Training and verification of the technical staff members’ competency must be documented. • An audit system should be in place in which observations of a predetermined number of transfusion testing procedures are done to verify that proper procedure is being followed.

33. Transfusion Process Oversight (cont’d) • Quarterly reports of audit findings • Regular reports of parameters the blood bank medical director deems necessary to monitor