Check Cells

[Kid At Heart]

Well, this is crazy. After all these years you would think there would be a consensus in our hospital blood bank. We need some current practice input here. For our tube testing method, the package insert for Panoscreen states to add checkcells to all negative and weak reactions. Some staff argue that reactions 1+ or less should have checkcells added. Others W+. What is your current practice please? Thanks for sharing.

[David Saikin]

I add them to any tubes that I cannot visualize agglutinates macroscopically (w+).

[Lcsmrz]

Same here ...

[Malcolm Needs ☆]

Same here...

[Brenda K Hutson]

Ditto...

Brenda

[eric1980]

We only add check cells to microscopically negative reactions. If it's a weak reaction, we will report it as such and will not add check cells.

What is the rationale of adding check cells to macro-negative, micro-positive reactions, and how do we interprete the results? I had always thought that if it's weakly positive, it is positive. So there's really no point adding check cells.

[TimOz]

To Eric,

We add AHG control cells to any macroscopically negative test.

Having said that, we also say that if you have well chosen reagents and test system system, the results should be read macroscopically ONLY for any routine test - ie Ab Screening, grouping and crossmatching. If results are weak or confusing, we would then say that you can go into investigation mode and the test is no longer routine and a microscope can and maybe shouyld be used depending on what you see. This of course does not apply to investigative and referrence labs.

I have seen labs in Asia that us Albumin additive method for antibody screening and then crossmatch with LISS (not additive but the old suspension method) and read the reactions under a microscope using a drop on a slide with a coverslip. Using this, everything is incompatible as far as I can see.

[Malcolm Needs ☆]

To Eric,

We add AHG control cells to any macroscopically negative test.

Having said that, we also say that if you have well chosen reagents and test system system, the results should be read macroscopically ONLY for any routine test - ie Ab Screening, grouping and crossmatching. If results are weak or confusing, we would then say that you can go into investigation mode and the test is no longer routine and a microscope can and maybe shouyld be used depending on what you see. This of course does not apply to investigative and referrence labs.

I have seen labs in Asia that us Albumin additive method for antibody screening and then crossmatch with LISS (not additive but the old suspension method) and read the reactions under a microscope using a drop on a slide with a coverslip. Using this, everything is incompatible as far as I can see.

I agree with Tim about the use of microscopes.

Peter Issitt, somewhere in the 3rd Edition of Applied Blood Group Serology (I'm not sure which page now; I read it cover to cover for my Fellowship examination, but that was many years ago) said that microscopes should be banned from Blood Transfusion Laboratories. Whilst I may not agree with him in every case, I do agree with him in principle.

[adiescast]

We also only add check cells to negative reactions. As Eric said, it doesn't tell you anything to add checkcells to a positive reaction.

I looked at all of the package inserts. The Panoscreen says as reported by Beth. The Checkcells says add to negative reactions. The AHG says add to negative reactions. The panels all say add to negative reactions. I think the Panoscreen insert may be a mis-print.

[eric1980]

My lab have been using microscopes since I joined and I have always been taking it as part of a routine BB.

So microscopes should not be used for routine tests? =S

If so, then in this context, macro-negative, micro-positive will be considered a negative reaction and should add check cells.

So we got to determine what defines a negative reaction?

[Malcolm Needs ☆]

My lab have been using microscopes since I joined and I have always been taking it as part of a routine BB.

So microscopes should not be used for routine tests? =S

If so, then in this context, macro-negative, micro-positive will be considered a negative reaction and should add check cells.

So we got to determine what defines a negative reaction?

I always take a macro-negative as negative.

EVen if there are a couple of cells "kissing" that can only be seen under the microscope, any resultant "incompatible" transfusion is not going to cause a clinically significant transfusion reaction. At worst, it will mean that the transfused red cells will not last as long as would be thought. It may cause a secondary reaction, but in most cases (almost all cases), unless the patient's bone marrow is compromised, their Hb will be back to normal with autologous red cells within a very short time.

Heresey I know!!!!!!!!!!

I await the world-wide flack!

:eek:

[adiescast]

We only read macroscopically when we do tube testing (most of our tests are solid phase now and there is no question of scoping those!). You definitely would not want to scope PEG enhanced tests. If you do have doubts and scope just to be sure, don't be looking for small, intimate groupings ("kissing" cells). There had better be a rock concert going on (many medium to large agglutinates in every field). Otherwise you will, 9 times out of 10, be chasing something that is not in the least significant. This is costly in terms of time and reagents. OK, now I will get off my soap box...

[TimOz]

Eric1980,

I think that using misroscopes is a little historical. When reagents were polyclonal and home made there was far greater variability and a general lack of sensitivity (although some home made reagents may be better). In this case microscopy has a place. In my opinion if you need to use a microscope (and I repeat) for the routine tests, there is a problem with your reagents. Use microscopy with PEG or Albumin techniques and everything is positive.

So that is my opinion and it applies to my lab but as with all of this, things are different in other labs and places and it would be interesting to actually do a simple study in your lab and see if you see anything potentially clinically relevant with microscopy that you miss macroscopically. Make a nice poster at a meeting!

An Malcolm, that's not heresy. It is common sense backed by experience and data.

[eric1980]

This is akin to opening a door to a new world to me. @.@

In my BB, after adding AHG/anti-IgG/anti-C' into a reaction, we will automatically read it under the microscope. We have a lot of "kissing" (new term I've learned) cells cases, which we picked up something non-specific almost all of the time. It really created more things to do, as well as delay of transfusion, for the rest of the patient's life in our record.

I'm not sure whether if it's the BB's rationale, but mine was "If it's there, it's there" and so if there's a reaction, something must be there. This was what I held in my mind when I interprete results all these years. But I didn't think about the chances of it being clinically significant, or the cost/benefit ratio (which I was not trained to think about until Malcolm posted in BBT).

Tim, I would love to do such poster, but I am no longer working in my lab's BB anymore.

If I could dig out a chance to mention this to my colleagues in BB, I will do so and hope that they could think about it...

[TimOz]

Here is a funny and peripherally related story.

I was training an elderly Asian gentleman on how to read and score BioVue cards. This was a small one man band private lab of an oncology clinic that grouped antibody screened and crossmatched transfusion dependant patients while they waited before topping them up (it was frightening). The guy I was training had what were obviously very strong and very old spectacles.

I made some weak reactions in a few cards and asked him to score them. He said "negative". I commented that he should say score 0, but look again. He said "score zero". I said no, look very closely, can you see the red cells agglutinates above the cell button at the bottom of the column. He said "no".

I asked him how long it had been since he had his eyes tested and he said about 10 years - then it dawned on me. I asked him if he was colour blind and he say "how did you know". I never found out what form he had but I suspect he saw grey dots on a background of grey dots. Maybe in this case some magnification would have helped but I think a change of occupation. He could not legally drive a train or fly a plane but he could do a crossmatch!!!

[eric1980]

This man needs to do an eye test ASAP! =S

And I am colour-blind too, but rest assured, I am very confident of my competency in scoring gel cards. ; )

My ex-supervisor went under the LASIK surgery back then, and she knew better than to be on the bench. So she pretty much did paper-work while recovering from the surgery.

However, in a moment of jest, we on the bench decided to ask her to score a weak reaction on a gel card anyway. Her reply was that it's negative.

So this man whom Tim trained should exercise judgement and responsibility and stay away from the bench until he's ready for it...