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At my facility, we've had two cases recently where an eluate was positive with specificity to an alloantibody even where the DAT (poly) was negative. My facility performs the tube DAT but we can perform a gel (MTS) DAT to back up what we do in tube since the gel is often more sensitive, at least where IgG is concerned.

Sure, in most cases, we'd never perform an elution if the DAT was negative to begin with, but occasionally a doc will request an elution if the DAT is negative, or we in the lab will take the initiative on a suspected hemolytic episode to perform an elution anyway, since as you know, coated cells can quickly be vamoosed from the peripheral circulation rendering the DAT negative.

2-3 months back, I found one case of anti-c in an eluate with a patient whose antibody screen was negative and DAT was negative, but I suspect it was passive since he'd recently received IVIG (he had no symptoms). In the other case, a tech suspected hemolytic disease, so she performed the DAT (it was negative), but she went ahead with the elution. An anti-K was clearly demonstrated.

Am wondering if this scenario (= DAT, + eluate) is not uncommon with other techs from around the country (and world).

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I've seen it a few times. Probably a situation where the DAT was just below detectable limits, and the eluate set the right conditions for detection.

We do eluates with only positive DAT too -- no reason to do otherwise routinely.

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At my facility, we've had two cases recently where an eluate was positive with specificity to an alloantibody even where the DAT (poly) was negative.

Is the antibody screen positive or negative? Mybe it is because not wash clear.
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The antibody screen was negative Shily...are you from India by chance? Noticed you mentioned performing minor xmatches in another post and I worked with a tech from India who did this.

Sure, since in the DAT, you're only testing one drop of blood versus an elution, where you're testing 1 ml of packed cells (huge volume difference), so you're bound to pick up more antibody specificity from an elution (a concentrating technique) vs. a mere DAT.

I'm wondering however in cases where the M.D. suspects a hemolytic reaction if the blood bank should perform an elution along with the DAT despite the DAT's negative result. I certainly wouldn't advocate doing elutions in most cases unless the suspicion was justified.

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When we perform workups for our smaller hospitals (I work in a donor center), we always do Gel DATs if the tube is negative. General difference is around a 2 plus . Anything over 2+ is usually seen in tube. Once we concentrate (eluate), we test in Gel. A surprising amount of these are clear antibodies when the screen was either negative or very weakly reactive. This is very common in recently transfused patient's.

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Thanks Opus...sounds like your facility is working in the 21st century :nod: At my facility, I always do a gel DAT with my tube DATs despite the fact that this isn't protocol where I am...and most of my co-workers don't try this. Also, our gel isn't validated where I am for elutions and they won't approve it, but I too will "sneak" in an elution in gel alongside the tube just to compare. I agree...it's probably more common than is acknowledged in post-transfusion situations.

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Thank you Labgirl153.

I am not an Indian. I come here just because I love bloodtransfusion medicine and want to learn more about it. This forum will not refuse a learner and a participant , ah? Thank you again for your post.

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  • 2 weeks later...

We recently had a patient who we were sure must have had a hemolytic transfusion reaction but we could not find any antibody (gel, liss, peg, you name it). The dat was negative both in tube and gel. How could we NOT try an eluate. (We never found an antibody in the eluate either.)

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Several years ago I saw a hemolytic reaction we think was due to Anti-C/e that we could not demonstrate in serologic tests. The patient had a catheter and when we gave blood postive for C and/or e the urine would turn red. When we gave C Neg e Neg blood, it did not. It might be a good idea to do some antigen typing on the patient. For example if patient is ccDEE, you might consider anti-C/e or if patient is Jk(a-), you might think about anti-Jk(a).

However, if this just happened with one unit, the possibility of a low incidence antibody is a consideration. Did you repeat the crossmatch with the implicated unit with a pre and post patient specimen?

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Thanks for the ideas. I did run the eluate on the 16 cell Immucor panel. We ended up antigen screening for Jka and Jkb. She tested negative for the Jkb so the next time we gave her Jkb negative red cells without incident. I did repeat the crossmatches, they were compatible.

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