Discrepancies in Immunohaematological Testing-Importance of Use of Multiple Modalities of Testing
Dr. Sitalakshmi Subramanian
Department of Transfusion Medicine and Immunohematology, St John's Medical College, Bangalore, Karnataka, India.
|Two cases are being reported here which shows that in case of immuno-hematological discrepancies, the standard mode of testing should always be supplemented by additional methods to gain an insight into further work-up. Case 1: A 28-year-old multigravida without history of co-morbidities, transfusion or drug intake, showed pan-agglutination with all commercial cells- three reverse grouping cells, Indirect Antiglobulin Test (IAT) and antibody screening on automated and manual gel-card and tube methods. Auto-control and Direct Antiglobulin Test (DAT) were negative on both platforms. Forward grouping was B positive on both platforms. Using in-house cells, automated and manual gel-card and tube methods, IAT was negative and reverse grouping was B positive. Suspecting reagent dependant reactivity and washing the commercial cells resolved all discrepancies on all platforms. Case 2: A 20-year-old lady without any history of any major illness or drug intake came for a routine check-up. Forward grouping showed 4+ reaction with Anti-A and Anti-D on automated and manual gel-card methods, but Anti- B showed double population with multiple commercial and donor-derived anti-B antisera. By tube method, it showed mixed field reaction. Reverse grouping was consistent with AB positive and Coomb’s minor cross-matches with AB positive units were compatible, with B and O units cross-matching was incompatible and with A positive units, it showed double population. DAT was negative and saliva testing confirmed secretor status for A and B antigens. Suspecting AB and A mosaic, cells were agglutinated with anti-B, the agglutinates allowed to settle and free cells re-suspended. This was done repeatedly to get a population of completely free cells that showed A positive on forward grouping. Both patients lacked any significant relevant history and did not want further testing. Counselling was done for them and their physicians about the discrepancies and safety of future transfusions. Hence in discrepant cases, repeat testing with atleast one additional modality is highly recommended as a first step to sculpting out a patient-specific line of management.|
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