Providing verification of an antibody specificity which is suspected but not proven by the referring laboratory. Reagent red cells with rare types may be needed to exclude the presence of underlying antibodies to ‘routine’ blood groups.
Investigations include the identification or confirmation of specificity and exclusion of further antibodies or when the referring laboratory has been unable to elucidate a serological incompatibility.
These are often from patients whose sera react with all red cells and for whom a compatible donor is difficult or impossible to find. The reactions may be due to a complex mixture of antibodies or to the presence of an antibody to a high incidence antigen produced by a patient with a rare red cell phenotype. Sometimes both occur in the same patient. Pre- and post-transfusion samples can be investigated in cases of haemolytic transfusion reaction. The Reference Laboratory has access to a large number of phenotyped red cells in addition to routine antibody identification panels and has direct contact with the services of the International Blood Group Reference Laboratory.
The results of all referred patients are held in eProgesa, the NZ Blood Service (NZBS) National Blood Bank Information System.
ABO and Rh(D) typing anomalies are investigated, including tests to distinguish between partial and weak D antigens.
Tests are performed to determine the class of immunoglobulin and/or complement bound to red cells.
In the presence of autoantibodies, of either ‘warm’ or ‘cold’ type, tests are performed to detect and identify any underlying clinically significant red cell alloantibodies. Recommendations are made as to the selection of units for crossmatching, or alternatively crossmatched blood is supplied.
Haemolysis suspected to be associated with the use of certain drugs can, with medical approval, be investigated.
Phenotyped units are supplied for patients with red cell antibodies. In addition, rare antigen negative units can be sourced from the national frozen bank or, in exceptional cases, from the International Panel of Rare Donors.
NZBS can provide crossmatched units in difficult cases, e.g. where there is a need to screen a large number of units or because the patient’s plasma requires treatment prior to crossmatch.
When a clinically significant antibody is detected during routine antenatal antibody screening it is important that the level of antibody activity is monitored through the pregnancy. This enables the potential risk of HDN to be assessed.
Samples may be referred from pregnant women with a positive antibody screen and tested to confirm specificity, to determine clinical significance and to exclude further antibodies. The service includes monitoring of antibody levels by titration, identification of possible further antibodies and red cell phenotyping of the father if necessary.
The causative red cell antibodies in cases of suspected HDN can be detected and identified by NZ Blood Service (NZBS).
Where necessary blood can be provided for transfusion whether from routinely available stocks or from special donors with rarer blood types who have their blood stored in liquid nitrogen.
A NZ Blood Service (NZBS) Transfusion Medicine Specialist (TMS) is available 24 hours / 7 days to provide clinical advice regarding the clinical significance of Reference Laboratory results or the transfusion requirements of patients where immunohaematological problems are encountered.
Similarly scientific advice in respect of blood bank investigation of immunohaematological problems is also available if required.