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jojo808

inconclusive antibody ID

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With an inconclusive antibody ID where all common, clinically significant alloantibodies have been ruled out, how long does one do 'full/complete' crossmatch until it is no longer necessary? 

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As long as the antibody screen is positive and/or your computer system is configured to classify an "inconclusive antibody identification" as "clinically significant".

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For as long as it takes to actually identify the specificity, so that you know whether or not it is likely to be either clinically significant or clinically insignificant.

Remember two things.  Firstly, the antibody may reappear as the result of an anamnestic response.  Secondly, if there is one specificity present, there may be others, one or more of which may be clinically significant.

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Agree with those who say that as long as it cannot be ruled as an artifact at some point, one must do a AHG crossmatch for the life of the patient.

Scott

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Even if the antibody screen is subsequently negative? Our night shift tech initially did a panel because one of the screening cells on this patient looked 'suspicious' A panel (Ortho panel A) was tested and there was one cell out of that panel that was a 1+. He then did panel B, which was completely non reactive. Of course all common clinically significant alloantibodies were ruled out. Now if this patient continuous to come back with negative screens ... you know I'm trying to find a reason why we can stop doing this without being irresponsible. 

So Smiller how would you prove it was an artifact? And Dansket what does your lab do if screens are now negative? Again trying to find an out. 

Thanks everyone in advance!

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In that case, I would have wanted to see the reaction with that one cell in panel A for myself.  There is most certainly a difference between genuine weak agglutination, and a couple of red cells "getting to know one another".  IF someone with real experience says it is the latter, I would be happy to go to either "immediate spin" or electronic issue.

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If Panel A has one cell with a 1+ reaction and all other cells are negative, I would call it positive. The iffy/suspicious screen cell that may or may not be an artifact becomes irrelevant. The patient would remain on full cross match forever due to the positive panel A cell. 

Trying to prove the reactions to be artifact at this stage may be very time consuming and still not resolve the issue. It seems more efficient to just do the full cross matches while the screen is being run. 

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IF it looks like a real reaction and it's only one cell then it may well be an antibody against an LFA. If you send a good sample from the patient together with the cell concerned to your reference centre, they may be able to identify it for you - although that's on an interest-only basis

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JoJo808,

Which test method is used for routine testing at your facility?  Were the "suspicious results" only observable by microscope? Were the night tech's "suspicious test results" reproducible?

Based on my routine testing protocol and detailed protocols for investigating "positive" antibody screens (that includes criteria for referring samples to a reference laboratory), I would not flag a patient with a history of "inconclusive antibody identification" for antiglobulin-crossmatching-in-perpetuity when subsequent antibody screens are negative.

It all depends on how well you feel your test system performs.  If I didn't have a tightly controlled system, I might choose to require routine antiglobulin crossmatches in perpetuity for patients with a single positive antibody screen attributed to an "inconclusive antibody identification".

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We use Ortho gel and you could see it macroscopically and yes it was reproducable. Again thanks for the great info. I think we will continue antiglubulin crosshatching for now and possibly discontinue it later. We did not send to our ref lab on the basis of one positive panel cell.

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On 1/8/2019 at 3:11 AM, jojo808 said:

Even if the antibody screen is subsequently negative? Our night shift tech initially did a panel because one of the screening cells on this patient looked 'suspicious' A panel (Ortho panel A) was tested and there was one cell out of that panel that was a 1+. He then did panel B, which was completely non reactive. Of course all common clinically significant alloantibodies were ruled out. Now if this patient continuous to come back with negative screens ... you know I'm trying to find a reason why we can stop doing this without being irresponsible. 

So Smiller how would you prove it was an artifact? And Dansket what does your lab do if screens are now negative? Again trying to find an out. 

Thanks everyone in advance!

By artifact I mean gel interference/mixed field/cold agglutinates that go away with a redraw or alternate method such as tube, proving that it was specimen or technique related and not otherwise.

The thing is, if you have even one stubborn positive cell, it could be a sign of a developing atypical antibody that might be significant down the line (if the patient is given blood from a donor with that particular antigen).  Granted -- I would think it's extremely unlikely that the patient would ever have a problem with a transfusion just because of a limited situation like this.

But I know of at least one big university hospital that will NOT bother with future AHG crossmatches in situations like these.

Scott

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Posted (edited)
2 hours ago, SMILLER said:

Granted -- I would think it's extremely unlikely that the patient would ever have a problem with a transfusion just because of a limited situation like this.

You know me Scott, I hate to look for zebras when I hear the sound of horses hooves (!!!!!!!!!!!!!), but did you see the reference below, where a patient "came across" the same donor a second time (fortunately ex-vivo).

Lemay A-S, Tong TN, Branch DR, Huang M, Sumner C, Oldfield L, Hawes J, Cserti-Gazdewich CM, Lau W.  The first case of severe acute transfusion reaction caused by anti-Sc2.  Transfusion 2018; 58: 2506-2512.  Doi:10.1111/trf.14867.

Edited by Malcolm Needs
ex-vivo should have been italicised, and wasn't; my bad!

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Oh no, I get it.  We do not dismiss things like this here out of hand either!  But I know of other Labs where they have different policies regarding follow-up testing for cases like these. (I suppose they would say that when they hear the sound of horses hooves they don't bother looking for aardvarks, pigeons or spyrogyra...)

Scott

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