Group and Antibody screen
Clinical Background:
Request Reason:
Pre transfusion testing and routine antenatal screening. A valid group and save is required to determine the ABO and antibody status prior to the issue of blood products such as red...
Request Reason:
Pre transfusion testing and routine antenatal screening. A valid group and save is required to determine the ABO and antibody status prior to the issue of blood products such as red blood cells, platelets, fresh frozen plasma (FFP). The ABO blood group has four principal types: A, B, AB, and O; there are two antigens and two antibodies that are mostly responsible for the ABO types. The specific combination of these four components determines an individual's type in most cases.
ABO testing involves testing a person's red cells for the presence or absence of A and or B antigens (forward group) and also testing the same person's plasma for the presence or absence of anti-A and anti-B antibodies (reverse group). Antibody screen/detection is a test used to demonstrate the presence of clinically significant alloantibodies (capable of causing haemolytic transfusion reactions or haemolytic disease of the foetus/newborn).
This test is performed to predict compatibility between recipient antibodies and donor red blood cells. If the antibody screen is positive the next step would be to perform antibody identification. If the screen is negative, there are no significant antibodies are present. Transfusion or pregnancy may stimulate the production of unexpected antibodies against red cell antigens through either a primary or secondary immune response. The timing of samples selected for compatibility testing or antibody screening should take account of this, as it is not possible to predict when or whether such antibodies will appear.
It is also important to note that all cellular blood components contain residual red cells and may elicit an immune response. To ensure that the specimen used for compatibility testing is representative of a patient’s current immune status, serological studies should be performed using blood collected no more than 3 days in advance of the actual transfusion when the patient has been transfused, received a transplant or pregnant within the preceding 3months, or when such information is uncertain or unavailable.
The 3 days includes the de-reservation period, e.g. if the sample was 1-day old, the blood would have to be transfused within 2 days. Where there has been no transfusion or pregnancy within the preceding 3months, the sample is valid for up to 3 months.
Test Details
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Discipline:
Transfusion
Transfusion
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Specimen Container Adult:
6mL K2 EDTA (Pink Top)
6mL K2 EDTA (Pink Top)
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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)
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Minimum Volume Adult:
6mL
6mL
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Minimum Volume Paediatric:
0.5mL
0.5mL
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Special Requirement:
Sample must be HANDWRITTEN and contain the patient’s forename, surname, date of birth and unique identifier (NHS or MRN number) all details on the sample must be identical to those on the request f...
Read MoreSample must be HANDWRITTEN and contain the patient’s forename, surname, date of birth and unique identifier (NHS or MRN number) all details on the sample must be identical to those on the request form. Samples labelled with addressograph or eRecord labels will be discarded.
Addressograph or eRecord labels are to be used on the Request Form ONLY.
The Request form Declaration MUST be signed by the person taking the sample.
Additional samples will be requested to resolve any discrepancies.
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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
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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...
Read MoreSample 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:
Compatibility Testing (Sample MUST be Valid)
All urgent add ons via telephone must be confirmed via email to the appropriate email address
tnu-tr.bloodsciencesadditions@nhs.net (internal)
Read MoreCompatibility Testing (Sample MUST be Valid)
All urgent add ons via telephone must be confirmed via email to the appropriate email address
tnu-tr.bloodsciencesadditions@nhs.net (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...
Read MoreThe 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.
The samples may require referral to an NHSBT reference laboratory depending on the clinical significance of any antibody detected in pregnancy. Once the investigation to identify clinically significant allo and/or auto antibodies is complete the laboratory can provide compatible antigen negative blood for transfusion or issue prophylactic anti-D where applicable.
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Factors Affecting Result:
Key factors affecting the results:
• Wrong blood in tube or laboratory transcription error
• Addressograph stickers or e-Record labels on sample tube
• Samples which recieved >24 hours form collect...
Read MoreKey factors affecting the results:
• Wrong blood in tube or laboratory transcription error
• Addressograph stickers or e-Record labels on sample tube
• Samples which recieved >24 hours form collected
• 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.
Unexpected/discrepant results in the blood group must be investigated further, and can indicate:
• Previous transfusion, bone marrow or stem cell transplant
• Weak or variant expression of the D antigen
• Significant sub groups of A or B
• Presence of an alloantibody (usually cold reacting such as Anti-M)
• Passenger lymphocyte syndrome in solid organ transplant recipients
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Referenced Documents:
4/1/15
4/1/15
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Routine Contact Name:
Section Leader:
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Routine Telephone:
Freeman: 0191 213 7849
RVI: 0191 282 4335Freeman: 0191 213 7849
RVI: 0191 282 4335 -
Specialist Test:
No
No
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Specialist Contact Name:
transfusion manager
transfusion manager
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Specialist Telephone:
0192 213 9169
0192 213 9169