Echo users - any false neg antibody screens?

[kate murphy]

Our validated 6 month old Immucor Echo has produced 4 false neg antibody screens in the past month. The first 2, after intensive investigation, we concluded were due to contaminated strips form one pouch of strips. All other repeated results agreed with testing with a different lot of screening strips and testing with another method.

Now we have 2 more. Not the lot. Not the strips. Echo functioning as expected, all maintenance up to date, QC passes.

One sample was 0, then 4+ when run with the same lot over a few days - a known Anti-E.

We've taken Echo off line, and we're not confident we'll reinstate it.

Our Galileo is up and running, no problems with that.

It seems that a process control we thought was in place to verify sample addition is not part of Echo's programming, as it is on Galileo. We were told there was a process control, and in fact, the Operator's manual has this process control.

Immucor has addressed this issue with Technical Communication to explain that bubbles/foam may cause lack of sample pipetting. We already do this, but it's a poor process control.

My question: are other users seeing these issue on Echo?

[marvy1]

We have had a few cases over the last couple years where we had a neg screen and then later found an antibody on a new sample. We went back to the old sample and re-ran it and found the antibody strongly reacting. Conclusion from Immucor was that the sample must not have pipetted into the well when the initial screen was done. That was when I found out there really is not plasma check done prior to testing. Antibodies in question were Anti-K and E.

[medtechristy]

Kate,

We are currently having this issue of false negative Echo antibody screens at our hospital and were told the same thing, that bubbles may be causing the sample to not pipette plasma. What was the resolution at your hospital and are you still having this issue?

[Eagle Eye]

this is not good.....You could miss an antibody and patient will have hemolytic reaction!!!!!!!! I under stand if you miss antibody altogether with ECHO and only picked up by Gel or PEG screen......This should have been addressed by manufacturere....What is the use of automation if you can not reproduce the same result???? I think I would prefer Gel non specific reactivity over "missed antibody"!!!!

[AMcCord]

We've seen one sample, that I'm aware of, with the foam problem. It was a case where a previously ID'd antibody was not detected with the antibody screen (anti-E). I have not seen 'new' antibodies which I suspected of being a miss on a previous screen, so I don't believe that we've missed a large number of antibodies. Fortunately foamy samples are quite uncommon in our patient population. It is something that also seems to recur with specific patients, so making a note of it in the patient's record may be worthwhile. I've communicated with all the techs to watch out for foam and remove it before placing the specimen on the Echo. I don't know what else we can do at this point. It would be a very good thing if that process control described in the manual was added to the Echo!

Fact is, process control is pretty shaky in tube testing - we should perform our testing process the same way every time to help ensure that we have done everything correctly every time...we should notice if the fluid level in the test tube we are holding is low (did I forget to add something???), but do we always? especially less experienced techs? or busy experienced techs? Automation should be an improvement in process control, and it is, but there is still no substitute for careful attention to what you are doing, whether it's a manual or automated process. I constantly harp on the fact that the Echo is only a tool . That it's a spare hand to help with the workload. We are still supposed to be the brain. (And every day, I hope everyone remembers to use their brain! :fingerscr)

Edited May 7, 2012 by AMcCord

[sdweaver29]

Can you exPlain to me what kind of samPles would be foamy?

Overall, what kind of performance do you get by having automation? If techs are not thinking through the process, with automation they will totally forget how to think as most get. Omfortable. We have had a provue for a few years now, now techs fear doing anything the tube method

[Injun Blood Doc]

This usually occurs when the lab technician brings reagents out of the refrigerator and either shakes or swirls red cell reagents to re-suspend them, and in the process, causes the antisera reagents to foam (high protein content permits foaming to last for a while). When the probe enters the foamy reagent, the level sense is fooled by the foaming and thinks reagent has been picked up. The proper technique is to bring reagents out of the refrigerator, make sure a stir ball is in all red cell reagents, and place on the instrument without mixing. The instrument mixes red cell reagents automatically if a stir ball is present. No foaming should occur.

[OxyApos]

So why is it so hard to pop the cap and inspect for foam in the patient specimen? We have lots of these, probably due to all of our specimens being drawn with vacutainers. Aspirate the foam or respin. The techs should be checking for short draws and hemolysis anyway. An antibody shouldn't be missed from foamy reagent...the LISS doesn't bubble up, like the Anti D typing reagents sometimes do.

[AMcCord]

Reagents for the Echo should not be mixed by hand. Techs should check the patient sample for hemolysis, short draw and foam. Exactly right! These things are not difficult to do nor do they take much time. Should be part of the routine. That's what I nag about.

What patients do we see with foaming? Vacutainer draws can cause foaming in specimens. In some cases if the needle is withdrawn before the tube is filled and the tube vacumn pulls air through your sample you'll see some nice bubbles. We have a few patients that seem to be foamy no matter how they are drawn and the foam does not go away even when respun. We have to snorkel it off - no big deal with that. These folks have been oncology patients, so I am assuming that there is something off with their serum protein levels. They are the ones that get a notation on their record to watch for foam.

What do we gain with automation?

We remove a lot of places for human error in the test process. (We do need to remember that NO system is 100% and absolutely error free. That awareness can help us detect errors when they occur - the false negs due to foaming are a case in point.)

With the current interest in keeping staffing levels as lean as possible, automation is important for improving workflow while maintaining or improving turn around times. And I think it's essential for maintaining sanity some busy days.

We still do some work with tube methods - confirmatory blood types, DATs, an occasional antibody screen for problem solving, cord blood samples, competency samples and CAP survey samples. It's enough to maintain competency and comfort with the manual methods. We all like to put samples on the Echo and walk away, but we are all capable of doing it the old fashioned way if we need to because we work at maintaining our skill levels. If you have a tech who is not comfortable with manual methods, maybe a little retraining time would help. We may change platforms as vendors make improvements, but I don't ever plan on going back to all manual testing.

[kate murphy]

We follow all that has been written - careful loading of reagents, checking all specs for hemolysis/foam prior to running, etc...

After the last post, we ran several known antibody specs repeatedly till spec was exhausted. Watched the instrument perform, made sure all reagents pipetted as expected and all steps ran as expected. Some variation in positivity is expected - no matter what methodology. But we did not expect a 3+ to repeat as a 0 with the same exact cells run only 90 minutes apart.

Immucor now advocates manual reading of all negative screens (!) Not really the reason we want automation!!

Immucor is now addressing some of these issues - more robust camera, incorporating process control steps, etc. However, the above cited positive specimen - when manually reviewing the negative screen, all staff polled would also have called it negative.

I'm not sure why the same methodology utilized on Galileo works like a charm, but on Echo does not.

I really was looking to see if other Blood Banks were experiencing the same issues which points more to a design flaw, rather than something we are doing.

[Injun Blood Doc]

Echo has had software and camera problems in the past, as you mentioned, with promised fixes in the works (Immucor has been promising these fixes a long time now). Seems Immucor has gotten too big to respond quickly - may be related to turnover of key personnel and management. The Echo camera processes four well images at a time, versus 48 wells for Galileo, so much more of the well is "seen" and processed on the Echo. Maybe the extra detail and information is causing problems on the Echo - I'm not an engineer or optics expert and am only speculating.

[estiner]

No we have had our ECHO up and running since Feb 2010 and have not seen this at all. We love our ECHO - it is so sensitive that sometimes we get positives that cannot be duplicated in PeG but not the other way around. We have a lot less problems than we did with gel. We do daily check on bubbles in the reagents when they are loaded onto the instrument. However, we usually get invalid if bubbles occur.

[AMcCord]

We are not a heavy volume site, so we're not running huge numbers of tests, but if it was a systemic problem or an instrument problem, I'd like to think that after 4 years running the Echo that I would have noticed it by now. I have not seen the problem you describe with non-repeatable (positive to negative) reactions on a particular patient sample. I have seen a few patients whose reaction strengths were 3-4+ on an Extend I panel and 1-2+ on a Ready ID panel....why? don't know. Is it possible it's something related to the specific patient - diagnosis, meds, contrast media infused prior to sample draw, protein issues? I'm sorry I don't have anything more to offer.

You mentioned manual reading of all the negative screens. That was something we were instructed to do routinely when our Echo was installed. Our Echo is not interfaced and we are manually reviewing results anyway, so it isn't a big deal for us. And again, we are not high volume, so that makes it not so time consuming to do. Probably not your situation at all! We definitely see more positives visually than the Echo does and the titers on those antibodies are usually so weak that tube testing with PeG (our backup method) either doesn't pick them up at all or only weakly. We are picking up some Kidd and Duffy antibodies that way. Maybe a camera upgrade will help with that. I was told by someone with Immucor that the original cameras on the Echos are just basic web cams, so the resolution is not real high.

[Eagle Eye]

I believe ProVue has ability to detect low volume of (sample/reagent)...it doesn't give interpretation if the volume pipetted was low. When you look at the card, you see very minor difference but/.....ProVue will not read those card. We see one or two specimen like this every Q...we repeat the testing.

[kate murphy]

I'm glad to hear that some Echos are operating well - we are swapping ours out for a new Echo and we'll see how that validates. I agree that Immucor has had some growing pains in the recent past and may not have had all the key staff necessary. Our Galileo is running great - very few issues there. Capture technology is good - sensitivity and accuracy is good and operating expenses are reasonable. So we'll give it another go, and I'll keep you all posted. Thanks for your help!

[AMcCord]

Hope the new instrument works out for you. Good luck!

[BBCLS]

How about the Neo? Do you see the same issues? We validated the Echo also but most of the staff still prefer Provue which we have now. Agent is pushing Neo.

Thanks.

[sdweaver29]

Please tell me why staff prefer to use the Provue over Echo. I am working on the Echo validation.