ABO\RH testing using Gel cards

[AUDREY]

We are currently using Gel cards to perform our antibody screens and ID's.This works for most patients. We are thinking about going to the ABO/RH gel cards instead of our current tube testing method. I watched a demo of these cards and the process seemed cumbersome, especially when compared to the ease of Gel antibody testing.

Money is tight and we will not be getting a Provue any time soon. I have read the posting on ABO/RH reverse discrepancies and I wonder how many of you are satisfied with the Gel ABO/RH process?? Is it as awkward as it seems or does it get better?

thanks!

[David Saikin]

What appears awkward about it? The only down side to using gel that I can see is the ten minute spin. We followed your scenario . . . absc/abid. After we were comfortable with gel we went "all the way". I haven't seen any more backtype discrepancies than I did using tubes. We use gel for as much as we can, including DAT (IgG/C3bd), ag typings, etal. We do still use tubes for IS XM, rosette testing, titers, STAT ABORh, and some antibody IDs.

[Malcolm Needs ☆]

We use gel typing for every single sample, unless one is sent in because of an anomolous ABO type (in which case we may not only revert to tubes, but also to human-derived polyclonal antisera) and we have had no problems whatsoever.

Yes, when you first start, it seems a bit fiddly, but the same can be said for most new technologies. You will soon get used to it and you may even wonder why you didn't do it earlier.

Most hospitals in the UK now use gel cards for ABO and D typing (usually automated) and we get sent in very few ABO anomolies (in fact, off the top of my head, I can only think of one occasion when a sample was sent in as such, that had a "normal" ABO group).

[TimOz]

Just a point about this thread. Gels aint gels!

The RCPA recently completed the second phase of an ABO grouping sensitivity study. The first was in 2004 and the second in 2008. This educational exercise went to all RCPA Immunohaematology subscribers and they are mainly i n Australian and quite a few Asian labs. This shows that certain brands of gel cards have very low test sensitivity. Our experience has also shown issues with very significant batch variability and I think quite a bit of instability. A few batches were recalled and one of these could not detect a normal A3 cell in our labs. This survey only covers 3 of the 5 common Column Agglutination technology systems (I prefer the CAT acronym as it is generic - gel is a few brands but this descriptor does not cover the Ortho BioVue which is glass bead rather than plastic gel).

When discussing this issue, remember that the the ID-MTS gel system as used in the U.S. is different from the DiaMed branded product found elsewhere in the world. and the newer Grifols system from Spain. The gel and plastic are the same but the ABD clones are different, are at very different potencies and have very different performance. This is hard to see with strong forms of ABO cells but throw a few weak forms in and see how they work.

If forum posters do not have their country or area identified, it is hard to know which gel system they are using.

Audrey, what gel system are you contemplating?

[RR1]

In the UK we see significant differences between the Ortho Biovue (which is glass bead based CAT) and Diamed (gel) CAT.

I think, but I am not entirely sure, that the UK Diamed system is the equivalent to the US Ortho ProVue system, just to confuse matters.

[Likewine99]

We have been using ABD/Reverse and ABD/ABD Ortho gel cards for well over 10 years. We find that the anti-D in either card is more sensitive than Ortho's anti-D tube reagent. We often have pts that typed Rh neg over 10 yrs ago with tube that are 2-3+ pos with the ABD gel cards.

We have had one instance when a donor unit that was labeled A neg from the blood supplier (using another reagent manufacturer) was 2+ Rh pos in a gel card and 2+ weak D pos in a tube test.

Like anything else new it was a little cumbersome at first but if we were to revert back to tubes our 20 techs that work in the BB would have a fit.

The only time we use tubes for ABO/Rh typing is the true emergent, actively bleeding patient and to do donor confirmations on the units associated with an active bleeder.

The generalists are comfortable with it and on eves and nights it gives the flexibility to walk away and do something else. Start your ABSC first and get it cooking, load the ABD/Reverse card, put it in the centrifuge. When the time is up spin them both together, you'll be amazed at how much time you have.

We have NOT noticed anymore ABO discrepancies that we did with tube, remember gel and tube testing are "tools on our BB toolbelt".

Gel reagents are cheaper for our organization due to the Materials Mgt people and contract pricing.

[AUDREY]

Thank you so very much for all of your responses!!

We are using Ortho Gel cards.

[swede]

We are planning on getting a Provue by year's end and will of course be switching from tube ABO/Rh to Gel. We have been using Gel for screens since 2001 and love it.

When you have switched to Gel typing and are now getting Rh positive with a history Rh negative, what are you doing? Are you switching the patient to Rh positive or keeping them Rh negative?

Also, for those few patients with no previous history that would have been typing as Rh negative in tube, but will be Rh positive in Gel, do you have a strength cut-off for Rh positive in Gel or is positive considered positive and the patient is Rh positive? I hope that makes sense!

[Sko681]

Hi, We currently use both gel and tube testing for ABO/Rh. We only use the gel on our automated analyzer. We found that not using gel exclusively was cheaper (we switched manufacturers). Also, we found that while gel testing is sufficient most of the time, it was more time efficient to use tube testing with critically stat specimens (because of the "10" minute centrifugation time of gel).

Also, we have noted issues in regards to the D antigen testing. The gel is much more sensitive and picks up D positive patients that were previously found to be D negative. Other issues that we have noted with the gel are mainly for the back type such as rouleaux, cold agglutinins, and antibody to the 0.8% reagent cell diluent. We have found that having the tube method reagents as a back up is very helpful. Our issues with the gel are few and far between though and most of the time works wonderfully.

[Sko681]

We are planning on getting a Provue by year's end and will of course be switching from tube ABO/Rh to Gel. We have been using Gel for screens since 2001 and love it.

When you have switched to Gel typing and are now getting Rh positive with a history Rh negative, what are you doing? Are you switching the patient to Rh positive or keeping them Rh negative?

Also, for those few patients with no previous history that would have been typing as Rh negative in tube, but will be Rh positive in Gel, do you have a strength cut-off for Rh positive in Gel or is positive considered positive and the patient is Rh positive? I hope that makes sense!

When we do find a discrepancy we have been keeping the patient as Rh negative. We have not established a cut-off for the positive patients, we have been calling them D positive regardless of reaction strength.

[David Saikin]

I have patients that in tube were classic weak Ds. In gel they are 3+ with the anti-D. John Judd's group will call D reaction of 3+ or less Rh negative; some folks use 2+ as Rh negative. There are some posts early on somewhere on this site with extensive banter about how to interpret these results. We call D+ reactions in gel Rh+, no cutoff as of this time to interpret as Rh negative.

[Malcolm Needs ☆]

I'm sorry, I know John has a very great name in Blood Transfusion/Blood Group Serology (and deservedly so), but I think he is wrong over this one.

If one is not sure about whether the individual is D+, D weak (still D+, of course), partial D or a true D-, then their blood should be checked at a molecular level. If then, there is no resolution, by all means treat them as a true D-, even if they are not.

[bbville]

We use gel cards for typing, but have had a ProVue for several years. The occasional bench typing we do is done by tube most of the time for no particular reason except it is quick. We retype units on the ProVue also with A/B/D/A/B/D cards. The discrepancies we have experienced have been rare. You will see some dual populations (non O patients who have received O blood or Rh neg pts who have received Rh pos blood) and need to deal with that in your procedure.

[Malcolm Needs ☆]

I agree with vsummerville. I don't think that i have ever come across a technology that will show up a dual population better.

We picked up a genuine chimera in Kent through this.

[David Saikin]

Malcolm - how about the anti-D in the cards used "across the pond". I believe the Ortho anti-D used in cards will not react with a Tippett Type VI D - is it the same over there? And you are so correct in the ability to detect dual cell populations.

Edited June 24, 2009 by David Saikin
Wanted to add more . . .

[Malcolm Needs ☆]

Hi David,

This is true for most cards, as the BCSH Guidelines state that partial D VI should not be detected in the case of a patient (despite this, I might add, we get a few in for confirmation every year from the hospitals), but there are some cards available that are marketed for use that will pick up partial D VI, for those that believe they need to know if a cord from an RhD Negative mum is a partial D VI (why, I really do not know!).

[NedB]

One of the best things about using Ortho gel (or any microcolumn) is the ability to see dual populations. When you get referred Patients, you don't always get histories immediately. Finding dual populations gives you an early clue.

[galvania]

If this works, I've attached a picture of an Rh phenotype ID-card (DiaMed - Europe) showing double populations

Anna:)

[Malcolm Needs ☆]

It shows the dual population beautifully galvania.

[SandyR]

Audrey - We also were doing ab screens in gel and ABDs in tube until now (ABD in gel was not available when we started) and when you do not learn these together it does seem cumbersome. (I felt your pain.) Too many variables or something. We did validate using saline as our diluent instead of adding yet another reagent so that helped a little. We are only calling 3+ & 4+ reactions for D as positive on routine patients and any reaction positive for cord bloods. That will more closely parallel our tube testing where we only did weak D testing on cord bloods. We're using John Judd from the University of Michigan as our reference. He's written and spoken on the D issue many times.