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RBC Units to Screen for Compatibility

Expected number of donor units to test to obtain a needed number of antigen-negative/compatible units.

RBC Units to Screen for Compatibility
Frequency of compatible (e.g. antigen-negative) donors
%
Number of compatible units needed
units
Complete the fields above to see the result.

When to use

  • Estimating how many donor units a blood bank should pull/test to find enough antigen-negative or otherwise compatible units for a patient with alloantibodies or a rare phenotype.

Formula

Expected units to screen = number of compatible units needed / (frequency of compatible donors, as a fraction), rounded up.

Pearls and pitfalls

  • This is an expected-value estimate; actual units required for a given confidence level can be higher due to sampling variability, especially for rare antigens.

References

  1. Dean L. Blood Groups and Red Cell Antigens. Bethesda: National Center for Biotechnology Information (NCBI); 2005.