Note: This is an update of a previous post.
In the previous posts I outlined how Medinfo handled antibody screening and identification. This post reviews how antigen matching is used based on these results.
There are two modes, regular and emergency. If the patient has not had at least two ABO/D determinations and/or does not have a recent antibody screen within the past 3 days, then emergency mode must be selected with its own rules. Otherwise, the regular mode applies.
In general, if there is a clinically significant antibody, an RBC unit which has not been matched for the corresponding antigen or has the corresponding antigen cannot be routinely selected. However there is a hierarchy here also:
- Absolutely prohibited release—no one can override the logic (e.g. giving group O to a patient with anti-H)—not even the transfusion medicine physician can override this
- Restricted release—only transfusion medicine physician can authorize the release of the incompatible or untested unit (e.g. giving C-positive unit to someone with anti-C)
- Least-incompatible for warm autoimmune hemolytic anemia WAIHA: requires transfusion medicine physician approval
- Informational release: authorized staff may release antigen-incompatible or untested unit but a pop-up menu appears and asks them to accept (e.g. Lewis untested unit in a patient with anti-Lea).
- Antigen-specificity matched—the usual mode for patients with antibodies
Examples of Regular Mode rules follow (these are not the complete lists but just provided to show the complexity of the process).
This is much more restricted for selection of ABO/D and other antigen typings. An example follows:
If low-titer group O whole blood is available, then a specific rule must be added to both regular and emergency mode to allow this to be given to any ABO type except Bombay.