Background/Case Studies: In donor testing, accurately labeling a blood unit with the correct Rh status is crucial to prevent sensitizing the recipient to the D antigen. After a donor testing facility transitioned to a new testing platform, inconsistent Rh results were observed for several long-time donors. These discrepancies were sent for molecular testing in hopes of determining the true Rh status of the donors.
Study
Design/Methods: Previously, RhD testing was conducted on the PK7300 analyzer (Beckman Coulter, Brea, CA). Currently testing is performed on the NEO Iris (Werfen, Norcross, GA). The PK7300 uses a bromelin agent to pretreat the cells before testing for the D antigen via agglutination with an anti-D reagent. In contrast, the NEO Iris D antigen test method detects hemagglutination using two anti-D reagents, as well as Weak D using a solid-phase red cell adherence assay.
Four samples sent to a donor testing laboratory showed contradictory RhD results compared to previous donor records. These samples were forwarded for molecular testing to help clarify the discrepancies. The results were then evaluated to determine the appropriate course of action for the donors.
Results/Findings: The results of the discrepancies are found in Table 1 below.
Conclusions: The results underscore the importance of having a standardized process to address donors who exhibit discrepancies between testing platforms. Implementing molecular testing has proven valuable in resolving such cases. Because there is no process to change donor blood type records at this facility and concern the product will be incorrectly typed by consignees, these donors are educated about their results and indefinitely deferred. However, if the ability to modify blood type data evolves in the future and increased RhD test sensitivity is adopted across institutions, these donors may become eligible for reacceptance. These donors may elicit an antibody response in Rh negative recipients and proper labeling of units is paramount to patient safety.
The donor testing center has been using the new test platform for 9 months. The percentage of these discrepancies has been low, but more are expected to be found. Our data suggests NEO Iris results for Rh types more closely align with molecular testing improving the characterization of donors' true D status and product safety.
