Gel Product Notification

[jssa1891]

How are you responding to Ortho's notification that their 0.8% rbcs may not detect anti -K or anti -E? The choices offered were: do nothing; incubate for 40 minutes or dilute 3% rbcs manually to 0.8% at the time of testing.

In parallel testing using PeG and gel, we have seen weak to negative reactions in gel with an anti-E that was positive in PeG, and this is using red cells that were diluted with MTS Diluent 2 at the time of use.

How long are you incubating gel panels - 15 minutes or 30 minutes? Forty minutes is starting to look appealing to me.

[donellda]

Are they referring to prediluted cells or cells diluted by the user? It sounds like cells diluted by the user. If so, is it a way for Ortho to try to get you to buy their prediluted cells?

[SandyR]

Orhto is referring to their prediluted 0.8% cells. We did a poster at AABB on the discrepancies we found between freshly diluted 0.8% cells and the prediluted 0.8% cells. In our case we found the reactions with freshly diluted cells matched our PeG reactions when we had enough specimen to run both. The 40 minute incubation didn't help the few times we tried it. We do a daily dilution of our Selectogens (from 3% to 0.8%). If our screen is positve we run a prediluted 0.8% Panel A. If the reactions do not match the strength of the reactions we saw with our Selectogens we dilute a 3% Panel B to 0.8%. I'm sure we missed a few before we adopted this process. We saw mostly Anti-E's being affected but we also had an Anti-K and an Anti-Jka. An Ortho researcher met us at our poster in Seattle and said Ortho is working on a new diluent for their diluted cells. Since then other members of the Ortho group have said that all antigens are affected and hopefully a new 0.8% product will be out in 2006. Ortho would like to hear from anyone seeing these problems and would like specimens to test.

[bmarotto]

The notification was about the prediluted 0.8% cells. One of the recommended options was manually diluting 3% cells with Diluent 2 which does not have the propylene glycol preservative.

We decided to continue using the 0.8% cells with 15 minute incubation. If a screen is positive and the panel is inconclusive but shows weak reactions with any K or E pos cells, we may investigate further with PeG and/or diluted 3%cells.

I have seen no data on the clinical significance of the "missed" antibodies. Those who have been around long enough will remember that enzymes detected Rh antibodies that were not detected by the routine methods in use at the time. These "enzyme only" antibodies were unlikely to be implicated in hemolytic reactions and most blood banks did not incorporate enzyme testing into their antibody screen procedures. We have known for years that no method will detect every antibody. I can't see adding 15-25 minutes to turnaround time to possibly detect a weak anti-K or anti-E of uncertain significance. Another thing to consider: would routinely incubating 40 minutes cause the detection of more nuisance antibodies?

If studies show these antibodies to be clinically significant, then we will reconsider our position.

[SandyR]

As an addendum, 2 of our weakly reactive Anti-E's are now 4+ reactions. One patient received blood at another facility and came back to us for more. The other patient was given E positive blood, reacted, and after the hemoglobin dropped 3 days after surgery we could only identify the Anti-E with freshly diluted 0.8% cells. So these seem to be clinically significant. I'd also like to add that when the sensitivity studies were done in the early days of gel there were no prediluted 0.8% cells available. Using the current prediluted product seems like taking a step backwards.

[Sandy Jo]

Today we had another Anti-E that was nearly missed with the Ortho Gel Methodology. There have been several in the last 3 years at this facility, although I really don't recall any in the previous 6 or 7 years using gel at another facility. This particular patient was transfused 7 days ago and had developed the Anti-E as a result of that transfusion. The tech performing a negative patient control with a (that) prior day's specimen detected the weak reactivity in one screening cell and then used PEG methodology to confirm the presence of a weak anti-E presenting more strongly with homozygous cells.

I am a strong believer that no one method detects ALL of the antibodies ALL of the time. I AM concerned about why one tech detected it and the other did not in a testing method that is considered to be more standardized such as Gel. I DO feel it is important to remind techs that increased workloads and pressures can breed familiarity and this shouldn't take the place of taking the time to read the Gel cards carefully and thoroughly, against a white background while observing both the front and the back of the Gelcard.

I do not want to routinely increase the incubation time with Gel as the turn-around-time (in batch testing) with this methodology is one of the important positive aspects of the procedure. What I am going to do is discontinue use of the prediluted 0.8% screening cells and dilute our own from 3-4% screening cells that we stock. I will continue to stock the prediluted 0.8% Ortho panel, but will instruct techs to consider increased incubation time when using that panel or to consider diluting a 3-4% antibody panel to use with gel testing. I hope this issue is resolved as soon as possible as I do like the gel methodology in general.

[bbbirder]

SandyR,

I am curious if you did any testing with LISS? Do you think these antibodies that did not show up withe Gel, but that PEG found would show up with LISS?

I don't doubt that some of these are clinically significant. But LISS misses an occaisionally clinically significant antibody also...

[bbkdiane]

I was not thrilled with the Ortho letter. We all knew about the issue with weak E's and other antibodies from a few years ago. Since we stepped up to Gel from tube testing, I felt that even though Gel had its warts, it was a safer system than tube testing for multiple reasons which we all know.

Now, Ortho's latest letter appears to be suggesting that we 'change' our procedures to one of 2 options. I didn't care for either option. We use a PEG screen to follow up weak Gel reactions before we waste time on a panel. When we do perform a Gel panel following weak Gel screen reactions we automatically increase the incubation time.

We've been on Gel for 4 years. It has enabled me to crosstrain some folks who were too scared to come into BBK for the lack of confidence in their tube shaking. Gel has standardized our tech to tech readings, and I can review the work of the helper techs on second and third shifts. Gel is great.

We look at our 4 year history and have not had any clinically recognized delayed reactions due to a Gel miss. I'm sure they are out there, but we have decided not to change anything. The only difference in the Ortho letter is that now they know why the problem exists and they will address the glycol issue. Before, they just stated that not one system detects everything and we were okay with that. Now that the reason is known, there is the need for the company to 'do the right thing' and give us interim options. I do not agree with the wording of the letter, however, I do understand where they are coming from legally. Now, it is our turn to make the decisions: go through your medical director and risk management department and let them assist you with your decision. We are legally comfortable with ours to continue with our current policies.

I also think we are a little irritated at this type of grey area issue because we have been the brunt of other legal grey areas such as random platelet bacterial testing (don't get me started!) and the old solvent detergent FFP routine (buried for good, I hope)

I want concrete guidelines that make sense, but lately, we seem to be recipient to wishy washy edicts from sanctioning organizations and vendors all due to the legal climate.

Thank you for listening.

[SandyR]

bbbirder - We did not test any of our patients with a LISS tube method. Our freshly diluted 3% to 0.8% selectogens picked up "something" and then a freshly diluted 3% to 0.8% panel or a PeG panel was needed to identify it because the prediluted 0.8% panel was either negative or weakly reactive. Conceding that not every technique picks up every antibody, we're talking about the same technique here - gel. Fresh dilutions work better than the current prediluted dilutions. The PeG tube method that we were able to run in parallel with some of our patients just verified our freshly diluted gel results.

To help those considering the risks involved we found 8% of our workups were affected. Those facilities that use prediluted 0.8% screening cells will never see this anomaly.

[David Saikin]

Is gel really worth all this? Is the increased sensitivity so important? Are people switching to gel because of Ortho "scare" tactics? If it is so good, why are some of these comments so lengthy? I know some institutions in my area are concerned because they find "something" in gel, but cannot get it identified . . . are these clinically significant? These are purely rhetorical questions from a non-believer. Don't give me the line that you can look at the work of your off-shift staff.