So wanted to see how the rest of you handle this scenario.

Unless you work in a Reference Lab and have the luxury of frozen samples of Low Incidence Antibodies, about all we can actually screen units for are Cw and Kpa. According to the AABB Standards, the expectation is that one should screen for antigens for which commercial antisera is availalble.

Now, fast forward to relatively small Hospitals in Urban areas.....

We recently had a patient with Anti-E,c,K and Kpa. Our Reference Lab is about 2 1/2 hours away with only intermittent shuttle service of specimens. So this weekend (of course, it is always on a weekend) our patient showed up needing blood. We happened to have some units that were E-c-K- in stock, but Kpa untested. The Tech. called wanting to know if she needed to send the units down to the Reference Lab to be typed for Kpa. The thought of that kind of made me sick! A few things came to mind:

1. Was the Kpa currently demonstrable (such that we could at least hope to catch it on the coombs crossmatch)

2. Did the Reference Lab have anything from that unit (pilot tube; segment; etc) that they could use to type from?

3. Given that we cannot type for most Low Incidence Antigens; but just Crossmatch for Compatibility, is it really mandatory in a case like this that we type the units for Kpa?

Just curious.

Thanks,

Brenda Hutson, CLS(ASCP)SBB

Okay, I'll put my old Hospital Worker's hat on, rather than wear my present Reference Laboraotory hat, and say that I would give cross-match compatible blood, whether the antibody was presently detectable or not.

Now I'll put back on my Reference Laboratory hat, and say that we would advise the hospitals on all but very rare occasions (possibly a warm auto-antibody being present, as well as a proven anti-Kpa) to give cross-match compatible blood.

Lastly, I would read the paper by Daniels G, Poole J, et al on the clinical significance of alloantibodies published in Transfusion Medicine a few years ago, and still advise that cross-match compatible blood be given. As I've said before on this site, I know there was a recent paper in Immunohematology about anti-Kpa causing a clinically significant transfusion reaction (although how clinically significant it was is a moot point), but that was a case where the anti-Kpa was missed because the screening cells were Kp(a-), and the Kp(a+) blood was given by either immediate spin or electronic issue (I don't have the paper to hand at home here), BUT anti-Kpa is really not that clinically significant.

Have a look in the literature and compare the number of cases of anti-Kpa that are known (thousands, if not tens of thousands), and then find all of the papers that cite it as causing problems (very, very few indeed - and some of those of dubious character).

So, by all reasoning, 3 was the correct answer, in my opinion.

Thanks for weighing in on that Malcolm; have been undecided for years!

Brenda

Our protocol for patients with antibodies directed against low incidence antigens is if the antibody is detectable, we use the patient's plasma/serum to screen for the antibody during the crossmatch. If the antibody is no longer detectable, we have the units screened for the antigen or use units historically negative for the low incidence antigen.

Sending a unit all the way to a reference lab and having it sent back for a low incidence seems absurd. Wouldn't the segments just suffice? We occasionally do antigen typing on segments and we verify the donation numbers and corresponding segment numbers.