Give me your two cents....

[vdvictory]

What do you think?

Patient has a positive gel antibody screen. Gel panels are suggestive of JKb and M (showing dosage). Night shift BB tech antigen types patient as positive for JKb and M. So it can not be Jkb and M. Night shift BB tech does a prewarmed tube antibody screen that is negative.

Day shift arrives....BB Tech informs next shift that they would have had prewarm crossmatched units ready if they'd had more time. Day Shift BB tech starts from scratch....Panels are a clear cut JKb and M showing dosage....Patient is JKb and M negative. Day shift BB tech gel crossmatches units that are antigen negative.

When questioned the nightshift tech said that they had followed procedure for antigen typing and when they got positive it threw them off. Said they would not have given blood without antigen typing units because it couldn't be ruled out on panel.

Was this patient in danger????

[Eagle Eye]

Yes!!!!! If the tech had time tech was going to do prewarm crossmatcch??????? Unless patient is transfused recently or AC is postive, when your patient is M+ & Jkb+ positive, was your tech going to give Jkb- & M- units???

Tech was ready to do prewarm crossmatch....that tells me patient was in danger??

This kind of technical error goes on my deviation form.

[RR1]

Possibly. As they had ruled out Jkb and M from the antigen type and their tube-IAT was negative...I presume they would have crossmatched by tube ?

Did another tech re-test the tube screen? If this was positive-it's possible the test was not performed correctly, in which case a tube xm would not have demonstrated an incompatibility (especially against a weak antibody).

Were you able to check their Gel cards and were pos and neg controls correct ?

Was the patient DAT positive (presumably not if the repeat antigen typing was neg)

Could an incorrect sample have been antigen typed?

The night tech however, did say that antigen neg blood would have been used, but....

If the patient antigen type was incorrect-how do you know the units would have been typed correctly (or do you obtain these from a different center)?

Seems like a bit of re-training is required....

I asked various staff what they would do if they had identified a straight forward anti-Fy or anti-S, but the antigen typing was positive. The response from some was to give anything!!!. Sometimes I think antigen typing confuses the issue for inexperienced staff.

[vdvictory]

Not sure how antigen typing was done if the "procedure was followed" and the nightshift tech still got wrong results. Tthe patient was indeed Jkb-, M-. I pulled out the first 4 units of blood in our refrigerator and prewarm tube crossmatched them....compatible. I also gel crossmatched them.....2 out of 4 were 2+ positive. It's hard to say what the tech would have actually done if time permitted. Would they have prewarmed like they had indicated to the day shift tech? Or would they have antigen typed like they said when questioned about it?

[Jaimie Nicholson]

I don't trust tube IAT very much any more, it seems like it's the test you do if you want a negative result I think that this patient might have been in danger of HTR if the prewarmed tube method had been used for Xmatch.

[RR1]

Either way, you need to ensure their training was current, and if it is, then thorough practical re-training is required from basic sample handling principles onwards. A few made-up problem scenarios could also be incorporated as a written exercise (you could get these from the Traq website or write your own-to check overall understanding).

Night shifts are difficult for everyone.....if this has never been a problem with them before- a bit of gentleness might achieve a better outcome.

Edited May 7, 2009 by RR1
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[RR1]

Hi Jaimie,

In the UK we consider the tube IAT to be the 'Gold Standard' technique. If this is performed correctly with adequate controls set up and weakly sensitised cells added at the end of the test, to ensure correct washing procedures...and the tech trained to read the test properly- it's an excellent test.

However, it is fiddly and the Gel test is excellent for routine use.

Edited May 7, 2009 by RR1
spelling

[Eagle Eye]

Most of your 1+ (some time even 2+) on Gel will always be negative. If my Gel is postive and tube is negative I give Gel compatible blood. If we need to give tube crosmatch(in case of warm auto) or prewarm crossmatch compatible)in case of stron cold abs) we need MD approval as our routine procedure is Gel.

At my place we do not allow prewarm technique unless it is approved by on call person. In this kind of case tech. would need to call supervisor before releasing unit.

We have several setps in place before we release blood for any patient who doesn't have clear cut antibody or inconclusive ab. I can sleep better at night with the process we have.

[Mabel Adams]

I must step in for John Judd and make his points about the "pre-fried" technique (aka pre-warmed). His lab did a study showing that this technique missed quite a number of significant antibodies. This was before they started using gel so was a comparison with a tube AHG technique using an enhancement, probably PEG or LISS--I don't remember. Pre-warming is often used to "get rid of" bothersome unknown reactions and that is totally inappropriate. It is often abused by heating the saline beyond 37 degrees (hence pre-fried). It is a saline only technique which means it is the least sensitive AG test out there. If I were looking at something that looked like a Kidd antibody, I would want more sensitivity, not less. Another point made clear in a pair of pro and con articles on pre-warminig in Transfusion a few years back was that no one should ever do pre-warmed testing without proving that a cold reactive antibody is present, i.e. one that is actually reacting at room temperature. There are other ways to bypass cold antibodies in tube testing that do not require the the risks of the pre-warmed technique. In places that do something besides tube testing routinely, the less experienced techs are not as likely to have that "feel" for reading the tube tests that us oldies developed after years of experience.

[Malcolm Needs ☆]

To answer the first point, yes your patient was in danger that night, and so was every other patient with clinically significant atypical alloantibodies.

The practitioner should not be allowed to work unsupervised (day or night, and however senior they may be) until a root cause analysis has been performed. This is not a disciplinary measure (although it may sound like it). It is purely to protect patients if the practitioner did something wrong (and I am not accusing him or her of having so done).

If the practitioner did follow the procedure and obtained markedly different results from other people, then it is certainly a case for re-training, and he or she should not be allowed to work unsupervised (day or night, and however senior they may be) until they have shown competency in a number of test conditions after the training has been completed.

The other thing that must be done after such an incident it to validate the procedure itself. You have to prove that the procedure is correct, and this should be done under stress conditions, if possible (very difficult I know, as "false" stress is almost impossible to do).

If the practitioner is found to not have followed the procedure, well...........I think that should become a disciplinary matter (but only if proved).

I agree with Rashmi that the pre-warmed (only to 37oC), warm-washed (with saline warmed only to 37oC) LISS tube IAT is the gold standard in the UK. However, I also agree with Mabel that it can be lethal in the wrong hands. It needs to be used on a very regular basis to get experience and maintain competence. I've seen people not mixing the red cells and the saline properly between centrifugation during the washing phase. I've also seen people hammer the tubes on the bench at the reading phase. Not surprisingly, they got false positive results!

[LaraT23]

Okay so if the patient was pos for both antigens to which an antibody was found, wouldn't the autocontrol be at least some what positive? I have ruled out based on phenotyping actually just recently my patient had an M, but the panel could rule out E, and Fya ( also V and Lea but am not worrying about those in our population). The patient was pos for E and Fya. But again, your AHG ( look Malcom I didn't say Coombs) crossmatch will catch those. Then if still not compatible, back to the drawing board. After all that, yes very much danger for the patient. We always do full XM for pos antibodies.

[Malcolm Needs ☆]

Hey, good for you Lara!

Either my thread on Nomenclature is getting through, or I've managed to bore the world into submission (probably the latter!).

I can just hear people rushing to their computers to tell me to substitute "certainly" for "probably"!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[RR1]

These are sometimes very complex problems to solve. As Malcolm mentioned, a thorough Root Cause Analysis must be performed. It is also very easy to blame individual staff for incidents when actually they have never really had proper (documented) training (i'm not saying this is the case here).

We are all under time and resource constraints where we work, and performing thorough training is so important, but not always easy to achieve. I personally feel that all staff that work in the Transfusion dept need a minimum of 5 days training a year + 1-2 days / month, to ensure high quality practice. Realistically, this just won't happen at the moment.

When I look at the incidents/ deviations occurring in my lab- the root cause seems to generally fall into the 'insufficient staffing to meet requirements' category.

[OPUS104]

We hear, on a regular basis, techs telling us that the sample they are sending us was positive on three of 11 cells but went away when they pre-warmed. We arent allowed to tell these facilites what to do, but we cringe everytime. We have started trying to get everyone to study CURRENT literature about the very present dangers of random prewarming. There are only a few times that we see a (I cringe to say justified) reason to even think about this "tricky" technique. Many of the seminars I have been to set out pretty strict criteria to meet before even thinking about this. I think many of our smaller hospitals are being taught the "thats how we've always done it" way of dealing with results that dont match up perfectly. Unfortunately this is another one of those subjects that everyone has their own opinion on. Good Luck to all who run into it, but for us it is not a usual choice at all.

[Malcolm Needs ☆]

I do totally agree with you OPUS104, that the technique can be tricky and most definitely is not to be used in inexperienced hands, but, in the right hands, it is still a superb technique.

I wasn't advocating going back to tile antiglobulin or capillary tube techniques!

[pluto]

To answer the first point, .................

I've also seen people hammer the tubes on the bench at the reading phase. Not surprisingly, they got false positive results!

Do you mean false negative results , if they hammer them on the bench the agglutination breaks up

[vdvictory]

The patient in question was actually negative for JKb and M. The nightshift tech performed the antigen typing wrong.

[Malcolm Needs ☆]

Yes Pluto, I do mean false negatives.

I wish I could say it was a deliberate mistake, but I'd better be honest.

[Joanne P. Scannell]

All over the place here ... yikes. Back to the facts at hand:

Yes, retraining is definitely in order here ... mainly about prewarming but also about using one's intelligence.

Prewarm should only be used when one is certain there is a cold agglutinin AND the method used in Prewarm Technique is not going to miss any clinically signficant antibodies (and yes, you CAN prewarm anything, including gel). Unless there was some indication that there is a cold agglutinin in the mix (eg. reaction at RT with pooled O cells and/or mixed field/cell reactivity with gel), then prewarm is NOT the way to 'automatically' go!

Gel is more sensitive ... don't expect tube testing to correlate with gel 100% of the time. The patient could indeed have a weak clinically significant antibody that is only detected in gel. Be careful when changing enhancement/procedures.

Unexpected results, ie. positive antigen typing for Jk(: The tech should have stopped, taken a breath, looked at his/her reagents carefully and repeated the tests ... we are human, we make mistakes.

Anti-M: Gel is well known to be super sensitive to Anti-M because of the acidity of the system. PLUS, I do remember reading somewhere years ago that if you looked hard enough, you'd find Anti-M in many plasmas. It's clinical significance needs to be determined ... enter 'prewarm' here. The clinical significance of Anti-M is up for discussion anyway.

Furthermore, patients producing Anti-M sometimes do type 'M-pos' ... most often because they are actually 'Mg-pos' (which is detected by your Anti-M reagent). So, we don't type patients for M at all ... in fact, I don't even stock the stuff.

[L106]

To: OPUS104

Would you be kind enough to list some of the current literature that cites the dangers of random prewarming? (We have a couple techs that jump to the prewarming technique a little too indiscriminately, in my opinion.) Thanks in advance.

Donna

[Sandy L]

We also use Gel as our standard method and quite agree that tube methods are less sensitive for most clinically significant antibodies than gel, (we use tube LISS as a backup). We would only prewarm when we have demonstrated a strong cold agglutinin (positive Immed spin/room temp in tube method. Most clinically significant antibodies that are 1+ in Gel will be negative in Tube LISS and many that are 2+ in Gel will be negative by tube methods. Prewarming reduces the sensitivity even further, so techs are insructed to consult a supervisor before using this technique. We use tube testing only in very selected instances, e.g. warm auto antibodies, potent cold auto antibodies, also those pesky antibodies that we used to call "HTLA" .

[Eagle Eye]

To: OPUS104

Would you be kind enough to list some of the current literature that cites the dangers of random prewarming? (We have a couple techs that jump to the prewarming technique a little too indiscriminately, in my opinion.) Thanks in advance.

Donna

Can you not specify in your policy to contact supervisor before perfoming prewarm?

[L106]

Sure, I could do that. But both my techs and I would feel better about that policy if we had some references that explained why the prewarming technique should be limited to certain situations and how/why the prewarming technique might sacrifice sensitivity. I would be interested in researching some of the current investigations that have been done with prewarming.

[Griffin L]

I would also be interested in current literature regarding prewarm. it is always easier to convince our pathologists when we have literature to site. I would appreciate a few current articles to consult.

[GilTphoto]

The first problem I see, is why did the tech get antigen positive for M and Jk(a)?. There was no mention as to whether the patient was recently transfused or DAT positive. They will both invalidate antigen typings. What antisera was used for M? Ortho's anti-M procedure requires NO SPINNING after RT incubation, while Immucor's does require spinning.

I have no experience with Gel, but do understand tube testing is STILL the Gold standard.

Most anti-M's I've seen are very strong and many are still reactive at IAT. Was the Jk(a) identifed with M negative cells?

We do our XM and Antibody screens using Immucor N-Hance, but require