In old days of only polyclonal reagents, QC of reagents took significant time. This has been simplified and easier since the introduction of monoclonal cocktail reagents.
Controls may be explicit (a specific control provided by the manufacturer) or implicit (implied by at least one negative reaction in the well of a gel card).
In order to properly interpret test results:
- Always follow manufacturer’s recommendations for performance of test AND use of controls.
- Use only the manufacturer’s specified control for testing. For example, do not substitute 6% albumin as the D-control if the manufacturer provides a specific control.
- Use manufacturer’s criteria for control validity.
Make certain test results meet the criteria for interpretation. Do not accept negative results for IAT typing if DAT is strongly positive (blocking antibody).
For both manual and automated tests, you can build the control criteria directly into your blood bank computer system’s truth table of results. This way the system will enforce the criteria and prevent false interpretations:
Example of control for ABO typing: