I have worked at 2 hospitals >500 beds. At both places, we performed immediate spin crossmatches for patients that had a previous antibody of undetermined specificity that is NOT currently reacting. What do you do in this situation? I have a tech who is questioning this protocol and would like any information you may have to offer her in explanation. There really is nothing I can find in the Technical Manual that addresses this.

Thanks, Jen

We would perform AHG crossmatch using MTS Gel. It is possible that the previous reactivity was to to antibody to low incidence antigen.

Stds says your crossmatching should be AHG, unless the Ab Screen is negative, and there is no prior history of an antibody. Then, a test for ABO incompatibility (IS XM) can be used. My thinking is that a patient who formed one antibody is certainly capable of forming another, and I want to find it before a transfusion reaction workup does.

Your SOP can differentiate between clinically-significant and -insignificant antibodies. A patient with an Anti-Lea reactive at IS but not at AHG may be best crossmatched at IS, if you don't type units for Lea.

We gel crossmatch any patient with an antibody.

If all clinically significant antibodies have been ruled out and the patient currently has a negative antibody screen, we do an immediate screen crossmatch. If the patient has a positive antibody screen, we do an AHG crossmatch if all clinically significant antibodies have been ruled out.

But how do you know if an antibody that reacts with only 1 cell is clinically significant if you can't identify it?

We would do a gel crossmatch since there is no way of proving if it was clinically significant or insignificant.

We would do an AHG crossmatch. We have lots of generalists working in the Blood Bank and it easier for them if we do an AHG crossmatch on anyone who has a current or previous alloantibody rather than having to decide what's clinically significant and what's not. Also, since it was undetermined, it's hard to know that it's not reacting now - maybe it's just not present on current screening cells, as would happen with antibodies to low incidence antigens.

We would do AHG crossmatch using MTS Gel.

At my current workplace, we perform a full x-match in tube (LISS) on these nonspecific antibodies. I'd prefer that we have the option to use gel as a backup method since it's more sensitive and less subjective but we haven't validated that protocol. Most of our "non-specific" positive Ab screens don't repeat over time, which can be attributed to something real like an antibody to a rare antigen, or to a tech's over-reading of reactions (more likely scenario). Unfortunately, most of our techs are old-fashioned and refuse to attempt gel as a secondary method to help them eliminate "junk" vs. the real deal. Also, most don't bother to eliminate the possibility of an HTLA since it's just easier to call it "nonspecific". Then we end up performing Coombs' xmatches forever and ever. Over half our antibodies called here are therefore "nonspecific". It's far from ideal.

I will use the method in which we find the the previous antibody and IS to do the crossmatch.