CLiaa & Prewarming Procedures

[ModernDayVamp]

a CLIAA inspector recommended some changes to prewarmed procedure. Specifically, she wanted to see written limitations on when the prewarmed technique is used so that we don't go to it too quickly.? gel used for antibody screens and IDs.? use tubes for back-up and trouble shooting and to give further information in problem cases.? the inspector may be trying to avoid techs going to a prewarmed method just to get a negative reaction and possibly ignore something significant.? She would like to see us list reasons that we believe it may be a cold and want to move to a prewarmed method as well as reasons that we should not move to a prewarmed method.? There are certainly specific things that are considered but it does seem difficult to come up with an exhaustive list.

Does anyone here have any advice on this issue.? Any thoughts would be appreciated.

[Lcsmrz]

I've always thought prewarmed technique was used in unwarranted situations, mainly when not knowing what you're prewarming away. Too many facilities see reactions <2+ and prewarm to see if the reactivity goes away. It has its greatest utility when multiple antibodies are present, one warm and one cold.

I like to know first what I'm dealing with: Anti-Le(a) barely reactive at IS, cold auto Ab reactive at RT or below, Anti-M that is nonreactive at IS but 2+ at RT, etc, etc. If I determine that the cold antibody is clinically insignificant, then prewarming is a valid technique to use to see if other, more significant antibodies are present..

[Malcolm Needs ☆]

If an antibody is non-reactive above about 30oC, it is NOT going to be clinically significant, whatever the specificity (with the exception of anti-P in PCH, which is a special case).

I would like to know on what personal experience, as opposed to reading learned papers, the inspector bases her knowledge about warming clinically significant antibodies (as opposed to potentially clinically significant) antibodies away. I wouldn't mind betting that it is not extensive, as there is very little (apart from John Judd's papers) about actual cases where truely clinically significant antibodies have been warmed away in the literature, and even John did not cite any cases where a clinically significant haemolytic transfusion reaction had occurred.

:(:(

[adiescast]

One thing that always bothers me is when people do a pre-warm without showing that they have an antibody that is cold reactive. When you are using IgG Coombs, are using only plasma samples, have reactions only at the Coombs phase, and do the pre-warm...what have you learned? I'm not saying that it isn't a cold reactive antibody; it's just less likely than it used to be with serum, polyspecific Coombs, and reactions at room temperature. I've seen people pre-warm Coombs reactions away and then, when someone finally does any testing at temperatures below 30 C, there were no cold reactions to begin with.

[Malcolm Needs ☆]

One thing that always bothers me is when people do a pre-warm without showing that they have an antibody that is cold reactive. When you are using IgG Coombs, are using only plasma samples, have reactions only at the Coombs phase, and do the pre-warm...what have you learned? I'm not saying that it isn't a cold reactive antibody; it's just less likely than it used to be with serum, polyspecific Coombs, and reactions at room temperature. I've seen people pre-warm Coombs reactions away and then, when someone finally does any testing at temperatures below 30 C, there were no cold reactions to begin with.

I agree in principle, BUT, when these people have pre-warmed away these antibodies, have they ever caused a clinically significant haemolytic transfusion reaction, or is it just that the more modern techniques of CAT and solid-phase (which, I will freely admit are more sensitive than the pre-warmed, warm-washed LISS tube IAT) are, actually, in many circumstances, over sensitive, and you are detecting non-specific rubbish (to put it scientifiically - because I cn't think of another, better phrase just for the moment).

:confused::confused:

[kharbert]

Here's an article describing clinically significant antibodies (Anti-D, for example) that weakened or disappeared with the prewarm technique:

Weakening or loss of antibody reactivity after prewarm technique

Regina M. Leger and George Garratty I

Volume 43, November 2003

TRANSFUSION

To be sure, the authors did not prove that any of these patients would have had a transfusion reaction if given blood based on the false negatives prewarmed caused--but with all due respect to Malcolm (and the respect due is considerable)-- is that a valid standard? It seems to me that that would be very very difficult to prove for many blood bank practices.

[Malcolm Needs ☆]

Here's an article describing clinically significant antibodies (Anti-D, for example) that weakened or disappeared with the prewarm technique:

Weakening or loss of antibody reactivity after prewarm technique

Regina M. Leger and George Garratty I

Volume 43, November 2003

TRANSFUSION

To be sure, the authors did not prove that any of these patients would have had a transfusion reaction if given blood based on the false negatives prewarmed caused--but with all due respect to Malcolm (and the respect due is considerable)-- is that a valid standard? It seems to me that that would be very very difficult to prove for many blood bank practices.

Yes, I have read this paper.

It is always very difficult, if not impossible, to prove a negative, and I would not for one moment deny that antibodies can be "warmed away". However, I go back to saying that these antibodies quoted are potentially clinically significant, and that there has not been a sudden decrease in the number of patients who have undergone clinically significant haemolytic transfusion reactions since the introduction of CAT and solid phase techniques, except for the introduction of some of the Good Manufacturing Procedures that have improved (a little) sample taking, sample identification and checks made before transfusion; in other words, procedural improvements.

I would not deny for one minute, however, that the pre-warm and warm-washing of LISS tube IAT is something that needs to be constantly practiced, so that the operator remains competent in detecting very weak reactions. I am more worried about the operator "bashing away" weak reactions at the end of the test, than the technique itself.

:redface::redface:

[hati]

We do a mini cold first , if it turns out to be positive,that's the only time we proceed to prewarm technique.

[AMcCord]

I also have a problem with people going straight to a prewarm procedure. The problem is that they are not THINKING first. They get reactions that scream warm auto and they prewarm. They get a weak reacting panel and instead of considering doseage, they prewarm. When the prewarm doesn't make all their problems go away, they stop dead, instead of addressing what they actually have. I am working on them to try a cold antibody screen first. IF that is positive, then prewarm. If it's not positive, then they need to try a different enhancement method (step down from solid phase), another panel, think doseage, all the good stuff we do to solve a problem. In other words, use a plan of action instead of the hit-and-miss method.

I did have a tech prewarm away a developing anti-Fy(a) one evening. The reactivity was weak, but the pattern was there with doseage. The patient was discharged immediately after transfusion and sent home 100+ miles away, so all we could do was notify her surgeon (who probably didn't do anything about it). The next time we saw the patient was for a surgical referral months later. Her anti-Fy(a) was then reacting 3-4+. Did she have any kind of reaction? If she did, we never heard about it.

Edited April 30, 2010 by AMcCord
spelling

[L106]

I also have a problem with people going straight to a prewarm procedure. The problem is that they are not THINKING first. They get reactions that scream warm auto and they prewarm. They get a weak reacting panel and instead of considering doseage, they prewarm. When the prewarm doesn't make all their problems go away, they stop dead, instead of addressing what they actually have. I am working on them to try a cold antibody screen first. IF that is positive, then prewarm. If it's not positive, then they need to try a different enhancement method (step down from solid phase), another panel, think doseage, all the good stuff we do to solve a problem. In other words, use a plan of action instead of the hit-and-miss method.

I totally agree with you, Ann.

[Deny Morlino]

You would think in the field we work in that strong logical thinking skills would be some sort of prerequisite. Strange that there is much evidence of people either not possessing, or failing to use this skill set. I agree as well...form a plan and work the plan to logically eliminate possibilities instead of stumbling around in the dark. Sometimes I am not certain if people truely understand the why behind what they are doing. OK, I relenquish the soap box to someone else.

[Malcolm Needs ☆]

I also have a problem with people going straight to a prewarm procedure. The problem is that they are not THINKING first. They get reactions that scream warm auto and they prewarm. They get a weak reacting panel and instead of considering doseage, they prewarm. When the prewarm doesn't make all their problems go away, they stop dead, instead of addressing what they actually have. I am working on them to try a cold antibody screen first. IF that is positive, then prewarm. If it's not positive, then they need to try a different enhancement method (step down from solid phase), another panel, think doseage, all the good stuff we do to solve a problem. In other words, use a plan of action instead of the hit-and-miss method.

In the WRONG hands, I would totally agree with what you say.

In the hands of fully trained, fully competent operators, such as Joyce Poole FRCPath, CSci, FIBMS, Head of Red Cell Immunohaematology at the International Blood Group Reference Laboratory (and her ilk), I'm sorry, but I would have to disagree.

:eek::eek:

[BankerGirl]

We had a patient transfered to us from another facility who had extensive workup done at their regional Red Cross lab. They identified anti-Fya and anti-E, but we had several extra reactions that we could not explain. We sent her to our ARC and they reported a non-specific cold antibody as well, so one of our techs prewarmed her next specimen 8 days later. There were some other clinically significant antibodies that she could not rule out, so we sent her to ARC again. They said that we pre-warmed away an anti-Jkb (we ruled that one out based on the pre-warm). The tech that originally worked her up here was actually worried about Jkb, but couldn't ID it for sure. The patient had other complications, so we were not able to say if the Jkb-positive units were a problem for her or not, but it sure shook me up! As it turns out, the next two specimens we tested showed no reactivity with Jkb positive cells.

[AMcCord]

In the WRONG hands, I would totally agree with what you say.

In the hands of fully trained, fully competent operators, such as Joyce Poole FRCPath, CSci, FIBMS, Head of Red Cell Immunohaematology at the International Blood Group Reference Laboratory (and her ilk), I'm sorry, but I would have to disagree.

:eek::eek:

A good reference person has the knowledge and something undefinable that I'll just call good instincts, for lack of a better description, plus enough experience to see the possibilities. They just 'know' where to go first - they 'see' it.

Unfortunately, my bench techs are what Malcolm would call the Wrong hands - good enough at the basics but not good enough to 'know'. They have to stick to a plan or they are never going to make it out of the maze. Some techs on some days I don't think even realize that they are IN the maze .

[Malcolm Needs ☆]

A good reference person has the knowledge and something undefinable that I'll just call good instincts, for lack of a better description, plus enough experience to see the possibilities. They just 'know' where to go first - they 'see' it.

Unfortunately, my bench techs are what Malcolm would call the Wrong hands - good enough at the basics but not good enough to 'know'. They have to stick to a plan or they are never going to make it out of the maze. Some techs on some days I don't think even realize that they are IN the maze .

There I would agree 100% with what you say.

What worries me is the seemingly blanket opinion that it is the technique that is to blame, rather than the operators.

I would absolutely agree that there is a certain "green-fingerness" about being able to perform certain techniques, and those who have not got this "green-fingeredness", and/or who have not been thoroughly trained and remain competent (by constant practice) should not be allowed anywhere near such specialised techniques; but it is not the technique itself that is at fault. This is why there are Reference Laboratories whose raison d'etre, amongst other things, is to remain competent in the more esoteric techniques.

:redface::redface:

[Malcolm Needs ☆]

We had a patient transfered to us from another facility who had extensive workup done at their regional Red Cross lab. They identified anti-Fya and anti-E, but we had several extra reactions that we could not explain. We sent her to our ARC and they reported a non-specific cold antibody as well, so one of our techs prewarmed her next specimen 8 days later. There were some other clinically significant antibodies that she could not rule out, so we sent her to ARC again. They said that we pre-warmed away an anti-Jkb (we ruled that one out based on the pre-warm). The tech that originally worked her up here was actually worried about Jkb, but couldn't ID it for sure. The patient had other complications, so we were not able to say if the Jkb-positive units were a problem for her or not, but it sure shook me up! As it turns out, the next two specimens we tested showed no reactivity with Jkb positive cells.

Antibodies to the Kidd antigens are notorious for being difficult to detect in vitro, and if there is even a hint that either an anti-Jka or an anti-Jkb is present, then Jk(a-) or Jk(b-) blood should be cross-matched, particularly as both are clinically significant nd can often cause an anamnestic response.

Did your tech try an IAT using enzyme-treated red cells, which is the most sensitive technique for detecting antibodies within the Kidd Blood Group System?

:confused::confused:

[BankerGirl]

Antibodies to the Kidd antigens are notorious for being difficult to detect in vitro, and if there is even a hint that either an anti-Jka or an anti-Jkb is present, then Jk(a-) or Jk(b-) blood should be cross-matched, particularly as both are clinically significant nd can often cause an anamnestic response.

Did your tech try an IAT using enzyme-treated red cells, which is the most sensitive technique for detecting antibodies within the Kidd Blood Group System?

:confused::confused:

We do not have enzyme-treated red cells, so that was not an option. Personally, I wonder if the Kidd was there the first time, but the ARC tech said she looked back at her first workup and it wasn't. We knew from the workup at the previous hospital that the patient was Jkb negative, which is what helped to cause our suspicions in the first place, but we deferred to the reference lab and gave what they sent us for compatible units (they actually did the crossmatch of record as well, since we sent them all our specimen).

[Malcolm Needs ☆]

We do not have enzyme-treated red cells, so that was not an option. Personally, I wonder if the Kidd was there the first time, but the ARC tech said she looked back at her first workup and it wasn't. We knew from the workup at the previous hospital that the patient was Jkb negative, which is what helped to cause our suspicions in the first place, but we deferred to the reference lab and gave what they sent us for compatible units (they actually did the crossmatch of record as well, since we sent them all our specimen).

I strongly suspect that this was also a case of, if there is even a hint of a Kidd antibody being present, assume the worst and assume that it is there; give either Jk(a-) or Jk(b-) units, whichever is appropriate.

In such a case, I should say that Reference Laboratories are not above "assuming"!

I had a case last Sunday morning (at 3 o'clock in the morning, actually, which made me very happy) that was a new anti-M+U. I did not have sufficient reference cells to rule out/in an anti-Jkb (M-, U-, Jk(a-b+) red cells are extremely rare) and so I just ordered M-, U-, Jk(b-) units from our National Frozen Blood Bank, to be on the safe side.

:D:D:D:D

[tbostock]

I have in my prewarmed policy:

Pre-warming should be used very cautiously, as it may result in the removal of clinically significant antibodies as well. Also, the use of no enhancement also limits the detection of any underlying alloantibody. This technique must never be used to eliminate unidentified reactivity.

I also have in my antibody ID policy that you must first detect a cold reacting antibody and perform a gel panel before trying to "get rid" of the cold by prewarming.

[AMcCord]

I have in my prewarmed policy:

Pre-warming should be used very cautiously, as it may result in the removal of clinically significant antibodies as well. Also, the use of no enhancement also limits the detection of any underlying alloantibody. This technique must never be used to eliminate unidentified reactivity.

I also have in my antibody ID policy that you must first detect a cold reacting antibody and perform a gel panel before trying to "get rid" of the cold by prewarming.

I LIKE your statement.

[L106]

So do I, Terri.

[Deny Morlino]

Policy work day today. I think I will "borrow" your idea Terry! I like the way you have phrased this point.

[GilTphoto]

In the past 6 months, we have had 2 patients with saline reactive (IS + RT) newly developing anti-K. Both were negative at IAT.

I believe in identifying all antibodies before prewarm.

[jayinsat]

In the past 6 months, we have had 2 patients with saline reactive (IS + RT) newly developing anti-K. Both were negative at IAT.

I believe in identifying all antibodies before prewarm.

AMEN! I've seen many anti-E's prewarmed away by techs with little knowledge of bb theory.

[C Lumbert]

I remember an article in the journal Immunohematology from 1994 titled:

Misidentification of anti-Vel due to inappropriate use of prewarming and adsorption techniques

Authors: J R Storry, D Mallory

Immunohematology / American Red Cro.... 02/1994; 10(3):83-6.

...later. Retrospective testing in our laboratory detected anti-Vel in both pretransfusion... examples of anti- Vel at the IAT. The posttranshision serum was grossly hemolyzed and anti-Vel... hemolysis) was strongly reactive (3+s) with Vel+ RBCs but compatible with 10 examples of Vel- RBCs...

The authors reported a fatal hemolytic reaction after the referring laboratory used the pre-warm technique in the rbc panel and crossmatches.

Granted anti-Vel is uncommon, but it seems that sufficient examples showing missed clinically significant antibodies using the pre-warm technique should justify caution in any investigation.