Transcript PowerPoint
Unit 8 Pretransfusion Testing Part 1 Terry Kotrla, MS, MT(ASCP)BB Introduction Purpose to select for each recipient blood components which when transfused will survive and not cause destruction of recipients rbcs. Must prevent transfusion of incompatible donor cells which may cause HTR. US federal government regulates by giving authority to CLIA to oversee testing: ABO/D Antibody detection Antibody identification Compatibility testing Pretransfusion Testing Requirements Positive identification of recipient and recipient’s sample. Review of transfusion records for previous results. Tests on donor blood. ABO/D recipient Antibody detection using serum or plasma Select ABO/D appropriate components Test serum/plasma with donor RBCs, i.e., crossmatch Labeling. Pretransfusion Testing Transfusion usually safe and beneficial. Donor or recipient RBCs may undergo accelerated destruction. Most HEMOLYTIC transfusion reactions caused by errors in patient or sample identity. Antibody may be below level of detectability. Even when all done correctly cannot guarantee survival of transfused RBCs. Pretransfusion Testing If performed PROPERLY testing WILL: Ensure patient receives correct components. Verify in most cases components are ABO compatible. Detect most clinically significant unexpected antibodies. Modern Blood Banking Practices Many changes over last 20 years. In 1980’s time for eliminating unnecessary tests. Ongoing reevaluation led to streamlining procedures for cost effectiveness AND patient safety. Intelligent approach, requires rigid adherence to guidelines and standards. Changes based on: Patient safety Elimination of unwanted reactions Increase speed of testing procedures performed. Transfusion Request Form Can be oral, electronic or written and must include information sufficient to positively ID patient. Two identifiers required: Patient full name Unique ID number Other identifier DOB Driver’s license number Photographic ID Blood is a drug and requires physician prescription. Transfusion Request Form Additional helpful information Sex Age Diagnosis Transfusion and pregnancy history Special needs: CMV negative, irradiated, etc. Reject requisition if Information is incomplete or lacking. Inaccurate Illegible Specimen Requirements Testing performed only as good as sample submitted. Properly collected sample from CORRECT patient is CRITICAL to safe blood transfusion. Patient must be identified with TWO identifiers, best to allow properly trained individuals to collect. Labeling Minimum patient full name Patient unique ID number. Date and time, although some institutions require date only. Phlebotomist identification Specimen Requirements Patient does not have armband physically attached. DO NOT DRAW Have qualified healthcare provider band patient. Emergency protocol must be followed in STAT situations Emergency room patient identity unknown use temporary ID. Preadmission testing must stress to patient importance of returning with ID band or will start over. Sample must be labeled in physical presence of patient. Specimen Requirements Commercial armbands may be utilized in addition to institution armbands. Top right: Typenex Bottom right: Bio-logics. Specimen Requirements Sample Draw into stoppered tube May use serum or EDTA plasma Can draw from IV line as long as proper protocol followed Hemolyzed samples should not b used Samples cannot exceed 3 days if transfused or pregnant last 3 months. Collection day is day 1, can be used until 11:59pm on day 3. Sample must represent current immunological status. No pregnancy or transfusion last 3 months the institution will set requirement for use. Specimen Requirements Infants less than 4 months old. No unexpected antibodies detected and infants receive no components containing clinically significant antibodies no additional testing required during neonatal period. After initial ABO/D type determined this test can be omitted during neonatal period as long as infant receives ABO specific or group O cells with compatible D type. Specimen Requirements Sample must be verified by qualified laboratory personnel. Any doubt as to identity of patient or labeling of sample new sample must be obtained. UNACCEPTABLE and EXTREMELY RISKY to correct incorrectly labeled sample. Each lab will have policies for accepting mislabeled samples. Must be able to defend in court reason. If sample can easily be recollected there should be zero tolerance. Study found mislabeled samples 40 times more likely to have blood grouping discrepancy. Specimen Requirements - Storage Sample and sample from donor RBCs (if crossmatch) MUST be stored at 1-6C for SEVEN days AFTER transfusion. Donor RBCs may be actual segment used for testing. Donor segment removed upon issuing unit may be saved. Must have sample for repeat testing if patient has transfusion reaction either immediate or delayed. Storage capacity will many times determine amount of time sample may be used. Three day sample plus 7 days = 10 days For non-pregnant/transfused for last 3 months may elect to use for 14 days + 7 = 21 day storage Previous Records Compatibility testing MUST include checking previous records for patient’s serological history. If patient has history must compare current with previous testing. If discrepancy present MUST resolve. NOTE: Becoming standard practice to collect SECOND sample after first for patients with no history. Most significant information is history of clinically significant antibodies Specificity compared to current antibodies detected. Regardless of result, may be negative, antigen negative blood MUST be provided. Serological Testing – ABO Grouping Test unknown RBCs with reagent anti-A and anti-B. Testing unknown serum with reagent A1 and B cells Discrepancies MUST be resolved prior to issuing blood. In an emergency provide Group O negative RBCs AB plasma products Serological Testing – D Typing Test patient and donor RBCs with anti-D. Tests with anti-D must be controlled to avoid incorrect interpretation. If problem arises transfuse D negative blood. Weak D unnecessary for recipients Donors No weak D test required at transfusion service. D typing of D positive donors not required by transfusion service. Weak D test must be performed by blood collection facility for donors. If positive labeled “D positive”. Antibody Detection Tests Serum or plasma tested against single-donor suspension of cells selected to carry blood group antigens necessary for detection of most important CLINICALLY SIGNIFICANT unexpected antibodies. Unexpected antibodies are those OTHER than anti-A and –B Clinically significant antibody is/has: Caused hemolytic disease of the fetus and newborn. Caused a hemolytic transfusion reaction Caused unacceptable survival of transfused RBCs Is reactive at 37C or AHG. Antibody Detection Tests IgG coated RBCs (check cells) MUST be used to detect false negative antiglobulin tests due to inactivation of Coomb’s serum. Commercially available screen cells, 2-3 vials, Group O Following antigens MUST be present: D, C, E, c, e, M, N, S, s, P1, Lea, Leb, K, k, Fya, Fyb, Jka and Jkb. No requirement for low incidence antigens (Lua, V or Cw) No requirements for homozygous cells to be present. May not be used beyond expiration, some antigens deteriorate. Type and Screen Safe alternative to full crossmatch. Perform ABO, D and antibody screen. When done correctly will detect 99.9% of unexpected antibodies. If antibody screen positive MUST identify antibody and crossmatch antigen negative donors. If antibody screen negative no crossmatch performed. Extremely safe and effective. Most frequently done for obstetrical and pre-operative patients where risk of bleeding is minimal. Type and Screen If complications arise patient can receive ABO, D type specific immediate-spin crossmatch compatible within 10 minutes. Transfusion service must have adequate stock of blood. Type and Screen - Limitations CANNOT detect ALL antibodies Antibody may be directed against low incident antigen absent from screen cells. Antibody may have fallen below level of detectability. Antibody may be exhibiting “dosage” affect, react more strongly with homozygous and weakly or negative with heterozygous. Type and Screen - Limitations Dosage RBC which is positive for Jka and Jkb is a heterozygous cell. Half of the antigens on the RBC will be Jka positive and half will be Jkb positive. RBC which is positive for Jka and negative for Jkb is assumed to be homozygous for Jka , 100% of the antigens will be Jka . Example of patient with Jka showing dosage reaction at AHG: Jka Jkb Patient 1 Patient 2 + 0 4+ 1+ 0 + 0 0 + + 2+ 0 References AABB Technical Manual, 16th edition, 2008 CAP Today http://tinyurl.com/4cd4qgd Basic & Applied Concepts in Immunohematology, 2nd edition, 2009 Ortho WIRE, http://www.ortho-wire.com