Newcastle Laboratories

Compatibility Testing

Clinical Background:

Request Reasons: Procedure of providing compatible blood products for transfusion either by serological testing or electronic issue. When blood or blood products are requested for a patient the pat...

Request Reasons: Procedure of providing compatible blood products for transfusion either by serological testing or electronic issue. When blood or blood products are requested for a patient the patient’s transfusion history including pregnancy, solid organ or bone marrow transplant must be taken into account. Patients who have been pregnant or received a solid organ transplant, bone marrow transplant or transfusion in the last 3 months must have a blood specimen, which is within 3 days (72 hour) to issue red blood cell products. Blood Products such as Platelets, Frozen products (Fresh Frozen Plasma (FFP), Octaplas, and Cryoprecipitate) and batch products can be issued on samples up to 3 months old; after this period of time a new specimen is required before further products can be issued. Small volume replacement transfusion can be given repeatedly during the first 4 months of life without further serological testing. After 4 months of age compatibility testing should conform to the requirements of adults. Where the patient has NO Historical group and only one sample has been received by the Blood Transfusion Laboratory prior to a transfusion request; a further group and save or group check sample MUST be received before the issue of Group specific A, B or AB red cells. In circumstances where red blood cells are required prior to the receipt of a second group and save the laboratory will issue ‘concessionary’ Group O red cells and group A/AB platelets and plasma until the sample is received and processed. There should be no delay in the provision of blood products. The presence of significant atypical antibodies in the plasma or a positive direct antiglobulin test (DAT) may reflect the presence of haemolytic disease of the fetus and newborn (HDFN) or an acute or delayed transfusion reaction (ATR, DTR). In those cases further serological procedures, where appropriate, should be performed to allow selection of appropriate red cells for transfusion. A clinical history and involvement of a Haematology SpR may be required to ascertain the need for further serological procedures. Types of Compatibility testing 1. Serological Testing. Serological testing is performed using the indirect antiglobulin test (IAT). It is used to detect ABO and non-ABO red cell antibody incompatibility between donor cells and patient plasma, by testing each donor unit against the plasma of the intended recipient. The (IAT) compatibility test is the default technique which should be used in the absence of functioning, validated IT or when electronic issue is contra-indicated. Generally patients with known alloantibodies or auto antibodies and neonates with maternal antibodies present require a serological IAT test. 2. Electronic Issue. Electronic issue (EI) is the selection and issue of red cell units where compatibility is determined by the LIMS without serological testing of donor cells against patient plasma. The ability to perform EI depends on the specific patient’s transfusion and antibody history and serological status of the current sample. The BCSH guidelines for the pre-transfusion compatibility procedures in blood transfusion laboratories (2012) and the BCSH guidelines for the specification and use of information technology systems in blood transfusion (2006) includes detailed guidance on the testing aspects of EI. NUTH Blood Transfusion laboratories routinely perform electronic issue and have a documented contingency plan, including a validated manual process, in case of IT failure.

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Test Details

  • Discipline:

    Transfusion

    Transfusion

  • Specimen Container Adult:

    6mL K2 EDTA (Pink Top)

    6mL K2 EDTA (Pink Top)

  • Specimen Container Paediatric:

    0.5mL K2 EDTA (Pink Top) or 6mL K2 EDTA (Pink Top)

    0.5mL K2 EDTA (Pink Top) or 6mL K2 EDTA (Pink Top)

  • Minimum Volume Adult:

    6mL

    6mL

  • Minimum Volume Paediatric:

    1mL

    1mL

  • Special Requirement:

    Sample must be HANDWRITTEN and contain the patient

    Sample must be HANDWRITTEN and contain the patient

  • Sample Stability:

    Short term storage: 24 hours at Room Temperature. Long term storage: 7 days at 4-6

    Short term storage: 24 hours at Room Temperature. Long term storage: 7 days at 4-6

  • Transport Requirements:

    Sample should be transported to Laboratory Medicine Reception via GP courier, hospital air-tube system or hand delivered to maintain storage conditions. Samples must not be subjected to extreme hot...

    Sample should be transported to Laboratory Medicine Reception via GP courier, hospital air-tube system or hand delivered to maintain storage conditions. Samples must not be subjected to extreme hot or cold conditions prior to testing.

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  • Add On Test:

    Telephone requests for further blood products Sample MUST be valid

    All urgent add ons via telephone must be confirmed via email to the appropriate email address

    RVIadditions.Laboratory@nuth.nhs.uk (...

    Telephone requests for further blood products Sample MUST be valid

    All urgent add ons via telephone must be confirmed via email to the appropriate email address

    RVIadditions.Laboratory@nuth.nhs.uk (internal)

    tnu-tr.bloodsciencesadditions@nhs.net (external)

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  • Interpretation:

    The presence or absence of antigens and antibodies is identified by agglutination. Agglutination occurs when the red cells are cross-linked by the binding of either IgG or IgM antibody molecules. T...

    The presence or absence of antigens and antibodies is identified by agglutination. Agglutination occurs when the red cells are cross-linked by the binding of either IgG or IgM antibody molecules. The pattern of reactions against a panel of reagents with known antigen or antibody status is used identify the antibodies or antigens present. The report will state the patient’s Blood Group and indicate whether alloantibodies are present or not and the units that appear compatible for the patient. Units will be available for a maximum period of 24 hours and if unused will be returned to stock. Positive Result (Incompatible) - Agglutination of the red cells is a positive test result and indicates the presence of the corresponding antigen to antibody. The presence of haemolysis with or without agglutination is also considered a positive test. Negative Result (Compatible) - No agglutination or haemolysis of the red blood cells is a negative result and indicates the corresponding antigen is not demonstrable. Mixed Field (Incompatible) - Mixed field populations may be detected as agglutinated red blood cells at the top of the column and unagglutinated red blood cells at the bottom of the column. It is recommended that patients with autoantibodies reactive at 37˚C are transfused with ABO compatible, K negative units which are of an Rh phenotype matched with that of the patient, to prevent the formation of Rh and K alloantibodies. If the patient has alloantibodies, units must also be negative for the relevant antigen(s). If haemolysis is very severe, blood compatible with an apparent specificity of the autoantibody could be transfused but clinical advice should be sought. For clinical transfusion advice please contact the on-call haematology SpR via the hospital switchboard.

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  • Factors Affecting Result:

    Key factors affecting the result: • Sample not valid • Incorrect specimen type received • Clotted, haemolysed, icteric or lipaemic samples • Insufficient plasma provided • Clotted samples may inter...

    Key factors affecting the result: • Sample not valid • Incorrect specimen type received • Clotted, haemolysed, icteric or lipaemic samples • Insufficient plasma provided • Clotted samples may interfere with instrument pipetting and must not be used. • Fibrin or particulate matter, clots, bubbles or scratches can interfere with reaction interpretations.

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  • Referenced Documents:

    4/27/15

    4/27/15

  • Routine Contact Name:

    Section Leader:

  • Routine Telephone:

    Freeman: 0191 213 7849
    RVI: 0191 282 43435

    Freeman: 0191 213 7849
    RVI: 0191 282 43435

  • Specialist Test:

    No

    No

  • Specialist Contact Name:

    transfusion manager

    transfusion manager

  • Specialist Telephone:

    0192 213 9169

    0192 213 9169

Availability:

All times Elective surgical procedures requireing compatible red blood cells must be received during core hours.

Turn Around:

Relies on specimen validity: Uncrossmatched: Immediate EMERGENCY: Electronic Issue (EI) - 10mins Serological Compatibility issue - 30mins ASAP: Within 2 Hours ROUTINE: Date and Time required

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