Hi all, we have an old SOP used for determining if a patient may have a purely cold allo (or two) or auto antibody . The cold panel SOP has no reference to anything ("we've always done it this way") in terms of how long a screen (which actually isn't even in the procedure) and/or subsequent panel should sit in the frig before being read.

 

Can any of you point me towards a useful reference so I can revise this procedure with proper references? Thanks!  I am assuming this is actually a useful procedure at times particularly when we are doing a manual screen and panel which reacts strongly at IS. We just moved to the Echo so I'm not sure yet how often we will determine that Echo positive reactions may end up being attributed to a cold allo or auto. We do frequent pre-warms here which sometimes makes me nervous but the cold panel is only used by one tech 99% of the time. I think I might want to get rid of this SOP? Hope this makes sense?

I would get rid of it immediately.

 

What antibody, apart, perhaps from an anti-P in PCH, that reacts only in the cold, is clinically significant?

 

If you find an auto-anti-I, are you going to give units of Adult ii blood?  No!

 

If you find an auto-anti-H, are you going to give units of O_h blood?  No!

 

If you find an anti-HI, are you going to give units of O_h that are also Adult ii?  No! - partly because they don't exist!!!!

 

So, if you can safely give I+ blood to someone who has a cold auto-anti-I, and H+ blood to someone who has a cold reacting auto-anti-H, why can you not give, for example, M+ blood to someone with a cold reacting allo-anti-M?  The obvious answer is that you can.  It is only when these antibodies have a wide thermal amplitude that they become remotely clinically significant (and that is very rare), and if they do, you will detect them in the warm.

 

The cold technique, in almost all cases, is a complete waste of reagents and time (both of which equate to a complete waste of money).

 

Put the SOP through a shredder!!!!!!!!!!!!!

I concur.  And pre-warming should only be done VERY rarely, and VERY carefully.

Oh boy. Thanks, I am so glad I ask these questions to all of you. I am about to take a few days of vacation and will take care of this when I return. These responses are probably why I can't even find a procedure in AABB tech manual on how to do this anyway. Vacation, take me away!!!

I concur.  And pre-warming should only be done VERY rarely, and VERY carefully.

 ..........unless you do it often and are VERY, VERY competent at the technique!

Oh goodness, how does one measure competency. That's another whole story

You will probably find very few, if any, reactions on the Echo that can be attributed to a cold allo or auto (depending on your volume and patient population). That's a very good thing! It helps compensate for the extra warm autos you are going to find  .

 

We used to see anti-M fairly often, but only 1 since we started using the Echo 6 years ago. After testing with a prewarm panel and coming up positive for anti-M, we did transfuse M negative cells in that case, under the assumption that it might be clinically significant. All those other annoying things like anti-I and anti-H and the vast majority of anti-Ms...you won't see them.

t. All those other annoying things like anti-I and anti-H and the vast majority of anti-Ms...you won't see them.

 

Not even IgG Anti-M?

How do you resolve ABO discrepancies without knowing what you are pre-warming? The back type cells are really screening cells with a flavor (ie blood type).

What do you do to resolve IM xm that are reactive? Just pre-warm without knowing what you are prewarming?

 

My fear is the patient that is developing a new aby that is present in the IgM phase but is clinically significant.

Alana

Very, very unlikely Alana.

 

Even human polyclonal anti-D, when it is forming and you happen to catch it when it is in the IgM phase, will react at 37^oC, rather than in the cold.

Not even IgG Anti-M?

 

Yes, you will see the IgG anti-M, though they are few in number. That's why we don't ignore the ones we see from the Echo - we assume that they are probably clinically significant.

I would get rid of it immediately.

 

What antibody, apart, perhaps from an anti-P in PCH, that reacts only in the cold, is clinically significant?

 

If you find an auto-anti-I, are you going to give units of Adult ii blood?  No!

 

If you find an auto-anti-H, are you going to give units of O_h blood?  No!

 

If you find an anti-HI, are you going to give units of O_h that are also Adult ii?  No! - partly because they don't exist!!!!

 

So, if you can safely give I+ blood to someone who has a cold auto-anti-I, and H+ blood to someone who has a cold reacting auto-anti-H, why can you not give, for example, M+ blood to someone with a cold reacting allo-anti-M?  The obvious answer is that you can.  It is only when these antibodies have a wide thermal amplitude that they become remotely clinically significant (and that is very rare), and if they do, you will detect them in the warm.

 

The cold technique, in almost all cases, is a complete waste of reagents and time (both of which equate to a complete waste of money).

 

Put the SOP through a shredder!!!!!!!!!!!!!

Amen brother Malcolm. Preach on.

Many years ago while in the SBB program, our training institution told us it was very (very!) important to ensure the room temp and below reactive antibody is not clinically significant by ruling out one of the few significant allo antibodies that react in this phase, specifically Vel.  They told us of a recent case (recent back then) of how this was not done and the consequences was fatal to their patient.  Was this just a "bedtime boggyman" story to scare the student blood bankers or is it important to perform cold screens to establish a clinically significant allo antibody is not present?    

Gee - unless you worked in a reference lab I don't see how you would be able to differentiate a Vel from an I with a cold panel.  I cannot recall the last time I saw a Vel neg cell on an antigram.