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Cold agglutinin SOP revisited


labgirl153

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Folks, need some tech info on my facility's cold mini-panel SOP. The SOP was written by a former manager who then provided no documentation, references etc. [gee, refs for any SOP should be a given, eh?].

The SOP states that all cells tested must react at > 2+ at 4C to consider the id "a cold antibody". Given that colds often don't react at exactly the same strength since cells vary in their "I" epitope numbers, all cells might react but some at 1+ while others react at 3+. According to the protocol, then even if all cells reacted, it would not qualify as a "cold antibody". I would even wager that if 3 out of 4 cells react - even with one negative, that a cold antibody is possible, if all other alloantibodies have been ruled out by other means.

Am saying that the SOP author arbitrarily chose a reaction strength level by fiat w/o any documentation that I can see. The technical manuals seem to be iffy on this as well. Our mini-panel consists of 2 screening cells, an auto control and one or both of the reverse cells (A and/or B) depending upon the patient's blood type.

Thoughts on this and if you don't mind, offer a better alternative SOP-wise. Thanks.:fingerscr

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labgirl153,

What is your intended purpose of the cold panel in your context, please? When I began to think about your question, I realized that I haven't done one since school. I wondered if that is because we use gel and don't see as many colds [though you can-and they have a weird look to them, but if we get one of those, we switch to tube PeG and it goes away], or because on the occassion that we do a tube antibody screen (always w/PeG) we no longer do an immediate spin, avoiding colds in the first place, or if it's because we give up on potential colds because we DON'T do a cold panel, and so we send them to a reference lab. So, in your context - you lab - what is the value of the mini cold screen to you? What prompts you to use it?

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Same here. Since switching to gel (no IS) there is little need to run a min-cold panel for interference investigation.

Having said that, a google search should turn up some procedure references for you. And of course, to change your SOP, you need your pathologist's input. If you are doing gel, you may want to ask if you can just drop it all together.

Scott

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Gang, my workplace uses both gel and solid phase. The solid phase instrumentation usually doesn't pick up on colds, but the gel actually does. I work in a high volume trauma hospital so we see just about everything. Most of the time we can get away with not detecting colds. Unfortunately, we perform I.S. crossmatches instead of electronic ones and we do sometimes start out in gel and pick up colds - so we can't ignore them.

An abbreviated SOP on cold panels is fine and I've seen my share of them here and there, but wanted a quick answer to this w/o having to dive back into the paperwork. Were it up to me, we'd have no I.S. crossmatches and would start all screens in sold phase. The prewarm technique has been frowned upon by the gods of blood bank for a few years now so we can't "go there" any longer. A quick panel to ensure it's "just a cold" is usually a winner but the protocol I have to deal with is nebulous at best. If you two don't encounter colds but rarely in your work then that's wonderful. I'll let others weigh in as they see this. Thanks.

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Actually, if the cold interference causes a big problem with our gel screen (we have a pretty good idea what cold agglutinin interference looks like), we would start a prewarmed tube screen. If time is a big deal, we would also simultaneously start a 30 min and a 60 minute settle. (I would think that "verifying" the cold with a mini panel does not help much by itself.)

Scott

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Scott, yes we too can readily see that it's a cold in gel...what do you mean by "settle"? Am assuming you allow the gel to sit for that 30-60" and then re-read? Do you perform I.S. x-matches and then prewarm them for a few minutes prior to re-reading them?

Mabel...when we suspect it's a cold in gel, we automatically run a panel in gel, then do a quick screen with 2 cells in LISS and PEG to ensure it's a cold ab. Then we proceed to a mini cold panel in 4C. I liked the prewarm panel technique from years back, and yes as you noted, one must first ensure it's a cold and not something more serious.

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  • 6 months later...

I am currently working on a cold procedure because EVERYTIME we get one (which is pretty frequently in gel) it is this huge ordeal that ends up being nothing. We have just purchased PEG and will be using that in a tube screen.

We usually see these in the gel screen, all 3-4+. We then do a tube screen in 4c. If positive, it is a cold. Run screen with PEG and the colds shouldn't interfere. (at least that is what I am hoping because that is what I have been told.) If the tube screen is negative we would go ahead and do the AGH crossmatch since the IS will probably be positive. I am still a little iffy on what do to as far as the crossmatch though. Our reference lab says no AHG crossmatch in this situation, but I think I would want to since there were issues.

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In the big debate over using prewarmed technique a few years back, one thing all agreed on was the need to verify that you actually had a cold antibody before you tried to prewarm it away.

Would anyone be willing to post their cold policies? We would like an SOP so we could know/prove we have a cold to justify doing a prewarm (we use tubes and PEG). Folks are still tempted to warm stuff away...:wow:

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