Bloood Bank


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Bloood Bank

  2. 2. Purpose of pretransfusion testing <ul><li>The purpose of pretransfusion compatibility testing is to prevent incompatible red blood cell transfusions that could lead to immune mediated hemolytic transfusion reactions. </li></ul>
  3. 3. Pretransfusion testing <ul><li>Pretransfusion compatibility testing prior to transfusion is extremely important and involves the following; </li></ul><ul><li>Blood Sampling and Clerical Checking </li></ul><ul><li>Blood Grouping </li></ul><ul><li>Antibody Detection Tests </li></ul><ul><li>Crossmatching Tests </li></ul><ul><li>Computerized Crossmatching </li></ul><ul><li>&quot;Type and Screen&quot; Policy </li></ul>
  4. 4. Blood Sampling and Clerical Checking <ul><li>In pretransfusion testing, the importance of careful clerical checking cannot be overemphasized. </li></ul><ul><li>From the outset, collecting and properly labeling blood samples from the correct patient is critical to accurate serological testing and safe blood transfusion. </li></ul><ul><li>When a sample is received in the transfusion service laboratory, a medical technologist must confirm that the information on the label and on the transfusion request form are identical. </li></ul><ul><li>The patient's serological and transfusion history must also be checked and the results of current testing compared with those of previous tests. </li></ul><ul><li>In short, any discrepancies must be resolved before blood can be released for transfusion. </li></ul>
  5. 5. ABO Grouping . <ul><li>Determination of the patient’s correct ABO group is the most critical pre-transfusion serologic test. </li></ul><ul><li>If the cell and serum grouping results do not agree, additional testing must be conducted to resolve the discrepancy. </li></ul><ul><li>If the patient’s ABO group cannot be satisfactory determined and immediate transfusion is essential, group O packed red blood cells should be used. </li></ul>
  6. 7. Rh Grouping. <ul><li>Rh grouping is performed using anti-D blood grouping serum. </li></ul><ul><li>Control must be run in parallel with Rh grouping tests performed on patient’s samples, to avoid incorrect designation of Rh neg, patient as Rh positive. </li></ul>
  7. 8. . <ul><li>If the Rh group of the recipient can not be determined and transfusion is essential, Rh negative blood should be given. </li></ul><ul><li>The test for D u is unnecessary when testing transfusion recipients . Individuals typing as Rh neg in direct testing should receive Rh-neg blood and those typing as Rh pos in direct testing should receive Rh pos blood. </li></ul><ul><li>As D u are considered Rh pos and may receive Rh pos blood during transfusion. </li></ul>
  8. 11. Antibody Detection Tests <ul><li>Besides clerical checking, grouping, and typing of donor and patient blood, the serum or plasma of the patient must be tested against a single-donor suspension of unpooled, group O reagent RBCs. </li></ul><ul><li>Such reagent cells are selected because they carry the blood group antigens necessary for detecting the most important &quot;clinically significant&quot; RBC alloantibodies, namely, those antibodies reactive at 37 degrees Celsius and in the AHG phase of crossmatching as opposed to those reactive at room temperature. </li></ul>
  9. 12. Continued… <ul><li>In transfusion service, a set of three unpooled commercial reagent antibody-screening cells are routinely used to test for the presence of RBC alloantibodies </li></ul><ul><li>In brief, three or four drops of serum and one drop of reagent cells are incubated at 37 degrees Celsius for 30 min, spin, read for hemolysis and agglutination, washed three to four times with normal saline, and then tested with anti-IgG using an indirect antiglobulin technique (IAT). The test results are first read macroscopically for agglutination and then, if negative, microscopically. </li></ul>
  10. 13. Continued… <ul><li>The AABB Standards also stipulate that blood from donors with a history of prior transfusion or pregnancy be tested for RBC alloantibodies, preferably at the time of processing. </li></ul><ul><li>Most blood banks test all donor blood for RBC alloantibodies because of the difficulty in determining donors' past histories. For this test, pooled reagent cells can be used to detect RBC alloantibodies to donor blood </li></ul>
  11. 14. Cross-match <ul><li>The two main functions of the cross-match test can be cited as, </li></ul><ul><li>I- It is a final check of ABO compatibility between donor and patient. </li></ul><ul><li>2- It may detect the presence of an Ab in the patient’s serum that will react with Ags on the donor RBCs but that was not detected in the Ab screening because the corresponding Ag was lacking from the screening cell. </li></ul>
  12. 16. Computerized Crossmatching <ul><li>In recognition of the improved capabilities of computer systems, the AABB has stipulated that blood banks may use computerized crossmatching, instead of serological crossmatching, to detect ABO incompatibility prior to transfusion and so prevent the release of ABO-incompatible blood components for transfusion </li></ul><ul><li>However, the AABB also stresses that such computerized crossmatching only be done if the following conditions have been met: </li></ul><ul><li>(i) The patient's ABO group has been determined twice (once on a current sample; a second time on the same sample, on a second current sample, or by comparison with previous records); </li></ul><ul><li>(ii) the computer system's database contains the donor unit number, the component name, the ABO group and Rh type of the component, blood-group confirmatory-test interpretation and identification, and the ABO group and Rh type of the patient; </li></ul><ul><li>(iii) a method is in place to ensure correct entry of data. </li></ul><ul><li>(iv) the system can alert the user to discrepancies between donor unit labeling and blood-group confirmatory-test interpretation and to ABO incompatibilities between the patient and donor blood </li></ul>
  13. 17. &quot;Type and Screen&quot; Policy <ul><li>In some special instances, crossmatching of blood is dispensed with according to a policy called &quot;type and screen.&quot; </li></ul><ul><li>This policy stipulates that blood does not have to be crossmatched in advance for patients undergoing surgical procedures usually not requiring blood. </li></ul><ul><li>The patient's blood is, however, completely tested for ABO group, Rh type, and RBC alloantibodies and then kept in storage by the transfusion service in case it is needed for crossmatching. </li></ul>
  14. 18. THANK YOU