Prewarmed crossmatch

[donellda]

We have had some discussion with regards to prewarmed crossmatches. By prewarmed I mean the true prewarm where patient's serum and donor cells are warmed separately at 37 for 10 before adding the serum to the cells, with the subsequent 30 minute incubation without LISS and the 4 washes with prewarmed saline before anti-AHG addition. My question is, how many institutions do an immediate spin crossmatch in addition to the prewarmed? A former blood bank manager at a facility that I worked at several years ago maintained that you needed to have a compatible immediate spin crossmatch in order to call the units compatible even in the case of a cold antibody where a prewarmed crossmatch was performed. In order to do this we prewarmed an additional set of donor cells and then did an "immediate spin" with the prewarmed serum and cells. This was not used for the incubation of the actual prewarmed crossmatch. So it has been my impression that this was necessary. Any thoughts?

[jssa1891]

In addition to the antiglobulin prewarm you describe, we also perform a "37 degree spin" prewarm, in which the serum and cells are warmed separately, incubated for 30 minutes, then spun and read. This is done if a "cold" antibody seems to be reacting at the 37 degree incubation phase and we wish to eliminate the interference. There are some antibodies, particularly in the Rh system, that may be reactive at the 37 degree spin phase only.

However we have never done an immediate spin prewarm. I believe the number of clinically significant antibodies that would be positive at IS but negative at 37 degrees and AHG is negligible.

When reporting out compatibility tests, we specify the type of test that was performed, so I don't think we are misleading anyone by omitting a test at the IS phase.

[David Saikin]

You can validate your prewarmed crossmatch to verify that it will detect ABO incompatibility. You can also validate it with your enhancement media.