We are having a major battle at my hospital right now. The "old techs" as they called themselves are putting up a fight because I want to do away with our prewarm procedure becuase there is no enhancement media. I was wondering what other institutions are doing.

It all started because one tech used 4 drops of serum to preform an IAT. Turns out this is normal for her as she doesn't want to miss an antibody. Package insert for LISS states the amount of serum to LISS needs to be in proportion to each other.

Long story short, does anyone out there still use the prewarm procedure without enhancement media? Thanks.

I use PW on occasion, but I do use enhancement with it (either PeG or LISS).

If you use it on occasion, do you use REST instead?

We are having a major battle at my hospital right now. The "old techs" as they called themselves are putting up a fight because I want to do away with our prewarm procedure becuase there is no enhancement media. I was wondering what other institutions are doing.

It all started because one tech used 4 drops of serum to preform an IAT. Turns out this is normal for her as she doesn't want to miss an antibody. Package insert for LISS states the amount of serum to LISS needs to be in proportion to each other.

Long story short, does anyone out there still use the prewarm procedure without enhancement media? Thanks.

I'm none too sure that I would count LISS as an enhancement medium, but I would definitely count PEG, albumin and enzymes as enhancement media.

We use pre-warmed LISS IAT almost every day in the Reference Laboratory, although we use column agglutination technology as the first "line of attack".

When I started training at the Blood Group Reference Laboratory in circa 1973, pre-warmed saline IAT (with an hour and a half incubation) was the norm. The 90 minutes incubation was largely because that was how long Rob Race and Ruth Sanger took for lunch in the MRC Blood Group Unit, and the BGRL adopted this technique!!!!!!!!!!!!!

Yes, we still use prewarm without enhancement occasionally. We have an SOP that details when and how to use it. I would retrain the tech using 4 drops LISS ASAP and make sure she is not modifying any other procedure/test. JB

I would retrain the tech using 4 drops LISS ASAP and make sure she is not modifying any other procedure/test. JB

I agree with you 100% Joan.

Incidentally, on rare occasions, will will still use pre-warmed saline IAT, when all else fails.

We occasionally do a prewarm with NO enhancement. Wow, 4 drops, that's a lot of serum!!

And as a former inspector, Madame 4 Drops is not following the SOP as written. :-??

Would using 4 drops in LISS be considered an FDA reportable error?

jb

answered my own question: RT-61-05 Testing performed, interpreted, or documented incorrectly for antibody screening

We do prewarm LISS screens here occasionally, but I have discouraged the use of pre-warmed screens because techs were using them to "prewarm out" what they were assuming was a cold reactive insignificant antibody. They didn't understand that prewarmed techniques were not designed to get rid of unwanted reactions, but rather to confirm the temperature range where the antibody is active.

Somebody died from an anti-Vel that was pre-warmed away. John Judd always disparaged the technique. It simply MUST NOT be done if you haven't first proved that there is indeed a cold antibody present. Then it must not be abused. John used to call it the pre-fried technique because techs would heat the saline to 40 degrees to be sure it "worked" (i.e. got rid of any reactivity that was annoying them). In modern AHG reagents it is seldom needed except in the presence of a very strong cold agglutinin. There was an article in Transfusion some years back that had two sides debating the question. Seems to me John Case was involved in the debate and he passed away quite a few years ago. I think the Tech Manual addresses it also.

It is possible to use increased serum/cell ratio in LISS but you must keep the proportions correct. There are those that say you can't just use 4 drops serum and 4 drops LISS because the saline the cells are suspended in is a part of the calculation of the proportions. Others say it is close enough. Maybe you should just change to PEG or gel as a better way to get increased sensitivity and not use up the sample so fast. Of course, you would have to have a procedure for it--and it would have to be followed.

She was using 4 drops of serum and 2 drops of LISS. I have talked to her and explained that can't happen. Thanks for the post.

We are looking into gel and hoping to get it in soon. We always perform a cold screen with our prewarm. But I want to do away with the prewarm and use REst instead. Do you use PEG? We are a small lab that only keeps LISS and albumin on hand.

I use PW on occasion, but I do use enhancement with it (either PeG or LISS).

For some reason I didn't see the last part of your statement yesterday. Duh. Thanks.

You DO have to be a little bit careful with RESt; it adosrbs out more than just "cold" antibodies.

Regarding RESt, I would be interested in some hospitals experience with it - - worth having or not? How about the cost and shelf life?

We used it here many years ago, when we still did tube testing but abandoned it at some point. We now use Gel routinely.

Thanks!

I am a small hosp too . . . my techs really bought into gel testing. I have never used REST - never really had the need to.

We are looking into gel and hoping to get it in soon. We always perform a cold screen with our prewarm. But I want to do away with the prewarm and use REst instead. Do you use PEG? We are a small lab that only keeps LISS and albumin on hand.

There wasn't any more to my statement . . .

For some reason I didn't see the last part of your statement yesterday. Duh. Thanks.

If you skip the immediate spin phase on antibody screens (not planning to detect ABO incompatibility there anyway, were you?), you will almost never need a solution for cold agglutinins. If you use anti-IgG for AHG testing and don't routinely read everything under a microscope, you will seldom find any colds. If you find weak reactions at AHG that you suspect are colds, then probably it is persistent agglutination, not antiglobulin-dependent reactivity. Repeat the test, but do only the antiglobulin phase and maybe even warm the LISS, cells and serum before combining them just to avoid any chance for cold agglutinins to react. No need to wash with warm saline. If it is completely negative now at AHG, it was probably a cold agglutinin.

Another trick is to test for persistent agglutination: repeat the test as usual but after washing but before adding the AHG, look at the tubes microscopically. If there is reactivity there, it is persistent agglutination from something that happened prior to the AHG phase--probably a cold. Once you add the AHG you can pin it and again read it microscopically and you may find essentially the same reactivity as you saw without the AHG. Although you wouldn't use a Coombs-only technique routinely, it can be valuable when avoiding colds. Of course you have to have proved there is a cold present first.

This is from years ago, before gel, when we had to think of these things. I had a long debate over it online with John Judd and John Case (who was a guru at Gamma before he retired and then passed on). John Case told me that the above approach was acceptable and he was not the one that absolutely forbade pre-warming. Judd also published an article in Transfusion a few years back showing the decreased sensitivity of the pre-warmed technique and all the antibodies that they missed using it--probably because of the lack of enhancement agents. Historically they used to say that PEG and LISS would enhance colds so that is why they weren't used. If you can use them pre-warmed and get past the colds, that's great. For what it is worth, we had an Ortho rep tell us to keep the LISS on the heat block all of the time to avoid any problems with colds. It always worked well for us but that was in the 80's before validation had been invented, I think. You wouldn't want to do that if it took you a month to use a vial. But small places that are always pulling the reagents out of the frdge (or nght shifts) can cause themselves a lot of trouble with colds by plopping that cold LISS into the tube.

K. That's all I've got on that.

We occasionally do a prewarm with NO enhancement. Wow, 4 drops, that's a lot of serum!!

And as a former inspector, Madame 4 Drops is not following the SOP as written. :-??

So I was flipping through AABB for fun and they say you can use 4 drops of serum to 1 drop of cells, if the proportion of LISS is kept the same. I still don't know where I am going to go yet with this issue.

I was always taught not to use enhancement on PW techniques because you do not want to enhance a cold.

I agree with Mabel 100% about the dangers of trying to "prewarm antibodies away". We cannot continue old practices just because "that's how we've always done it".

Agreed Terri, the pre-warm is a dangerous technique in inexperienced hands.

 

In experienced hands, however, it is a VERY useful and SAFE technique.  We have used it in our Reference Laboratory day in, day out for years and years as a back-up technique, and STILL have not killed anyone.

 

       

I pretty much use PW only to determine if an anti-M is clinically significant or not (after r/o other allos).

To those who use LISS tube method, do you perform any quality control on LISS reagent? If yes, could you please share how often and how you do it?

Thank you in advance.