Turnaround times
The quoted turnaround time is from sample receipt in the laboratory, to results authorisation in the Laboratory Information Management system. The times do not include transport of specimen to the laboratory or the administrative process to print and post/email reports. Service users must allow for transport and reporting time when ordering tests.
Clinical background :
Knowledge of a patient’s extended phenotype can help in the investigation of, and blood provision for, autoimmune haemolytic anaemia (AIHA), sickle cell anaemia and patients requiring multiple transfusions. It is also used in bone marrow donor preparation and also as part of an antibody investigation profile. It is recommended that transfusion dependant patients (i.e Thalassemia syndromes, severe aplastic anaemia, sickle cell disease and other congenital or acquired anaemias) have an extended phenotype performed prior to any transfusions and that Rh and K compatible blood is used. Extended phenotype are also performed on patients who have newly identified alloantibodies and/or non-specific/auto antibodies and are expected to receive numerous transfusions (i.e. Haematology, PBSC Donors, Oncology, Solid Organ Transplant, Renal and Multi-Transfused patients). Phenotype investigations as required to determine the antigens carried on a red blood cell (RBC). The “phenotype” of any blood group refers to which antigens are serologically detectable on the RBC, and usually (though not always) corresponds to the genes that the patient carries. The test procedure is based on the principle of agglutination. Normal human red cell, processing antigens, will agglutinate in the presence of antibody directed toward the antigen. Extended phenotyping tests for the D, C, E, c, e, K, Jka, Jkb, Fya, Fyb and MNSs antigens.
Specimen container paediatric :
1mL EDTA or 6mL EDTA
Specimen container adult :
6mL K2 EDTA (pink top)
Minimum volume paediatric :
1mL
Minimum volume adult :
6mL
Special requirements :
Test can be ordered via EPR PowerChart and taken with the BloodTrack bedside sample labelling system.
The Trust operates a zero tolerance policy. Deviation from Trust Sample Labelling Policy will result in the sample being rejected and a repeat requested.
Sample stability :
Short term storage: 24 hours at room temperature.
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 or cold conditions prior to testing.
Add on test :
Request for add on must be discussed directly with the Transfusion laboratory.
FH: 0191 2237849
RVI: 0191 2824435
Interpretation :
The presence or absence of antigens is identified by agglutination. Agglutination occurs when the red cells are cross-linked by the binding of either IgG or IgM antibody molecules. The blood group antigens reported will show whether the patient is positive (demonstrates the antigen) or negative for the antigen type.
Factors affecting result :
Incorrect specimen type received, clotted, haemolysed, icteric or lipaemic samples. Clotted samples may interfere with instrument pipetting and must not be used. Fibrin or particulate matter, clots, bubbles or scratches on the test cassette can interfere with reaction interpretations.