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Missing "D's" on the Galileo???


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We seem to be having a problem lately, getting a lot of D negatives on our Galileo. Per the AABB Standard, we don't routinely test for Weak D, which leads to mass confusion when the prenatal patient delivers and the hospital does test for Weak D, and the OB calls us demanding to know "what happened". Recently, we re-checked the patients's history (as usual) and she was Rh negative on 2 previous occassions. After testing as D positive in the hospital, the doctor ordered Weak D typing. She typed D negative again on our Galileo, but when we tube typed her, she was weakly positive. Upon RT incubation, she was 2+ (Immucor). So we tried using Gamma (monoclonal) and she was immediately strong 3+ at immediate spin. Yet still, on the Galileo, she results as negative, and we're stuck trying to explain this to her doctor. Anyone else seeing anything like this? Suggestions? (And no, we can't use the Gamma on the Galileo because it does not have a barcode!) :cries:

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We have seen this problem twice in the last month on our Echos.

The first case was a patient who had weak D testing performed accidentally, and the Echo reported it as weak D pos. The patient then typed as Rh pos in tubes using Immucor's monoclonal D rgt.

If you happen to discover anything, please post, as I am very interested in this problem myself.

Karen

The second case is an oncology patient who also had weak D testing performed accidentally. In this case the weak D testing was positive. When the patient needed additional blood 2 days later, a tube retype found the patient to be Rh pos.

Currently our policy is to perform weak D testing on all females <50 years with no previous history. If it were not for our techs forgetting the age requirement, we would not have caught either case. Although not detrimental to the patient, our Rh-neg blood inventory needs all the help it can get.

I mentioned this in passing to Immucor, and they did not know of any problems with this. If I find any more occurances, I will be putting in a call to tech support.

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krickards: You still perform the weak D testing on prenatal patients, even though the AABB Standards changed? I am just curious because we do not perform Weak D testing on prenatals (or anyone for that matter, due to the AABB Standard) and I find myself faxing copies from the Technical Manual nearly every day to OB's about Weak D.

I'm going to call tech support at Immucor today, as we have seen too much of this. I'll keep you posted.

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I know the standards have changed since our last policy revision. I had planned on getting us up to date on that in the very near future, but am now hesitant to take any action until the problem is resolved. We can't get enough Rh neg units to take care of our true Rh neg patients without adding false Rh negs to the mix! I'll be very interested in what Immucor has to say.

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I know the standards have changed since our last policy revision. I had planned on getting us up to date on that in the very near future, but am now hesitant to take any action until the problem is resolved. We can't get enough Rh neg units to take care of our true Rh neg patients without adding false Rh negs to the mix! I'll be very interested in what Immucor has to say.

That makes perfect sense to me. Had it been up to me, I would not have changed the standard in the first place. Seems more reasonable to test for Weak D anyway.

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I heard from Immucor just now. If you check your user manual under "Limitations", Section 9 - 7, it states, "Warning: The Galileo cannot reliably detect hemagglutination reactions that are graded as 1+ or less in test tube methodology. The Galileo does not differentiate mixed-field reactions." So any of our patients who are 1+ or less are going to show up as Rh Negative on the Galileo. I'm not quite sure how we're going to handle this, as we test several hundred samples per day.

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I think I would rather call a weak or questionable result "Rh negative" and give them Rh negative blood and RhIG than call them positive and have a partial D that gets sensitized. We follow John Judd's recommendation and anything less than 2+ with anti-D in tube is called Rh negative. He recommened less than 3+ when testing using gel. (I am not talking about donor testing, just patient).

Not all reagents are the same, and they react with different D variants differently. You should see some variations in reactions with different reagents and methods.

There have been multiple articles about this, and most recommend dropping the weak-D test.

Linda Frederick

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Thanks for all the information! I checked the Echo's manual, and it has the same limitation on tube reactions of 1+ or less. I think the solution for our facility will be to hurry up and discontinue weak D testing as quickly as possible. This way, we will catch fewer of these situations. If no one knows there's a discrepancy, then we'll all sleep better at night!

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WE dropped weak D testing on all patient's except babies of Rh negative mothers years ago and have not seen an increase in Rh negative patients. There just aren't that many weak D people out there to justify doing weak D just to save a few Rh neg units. That is an old tired worn out excuse not to let go of the past. Time to move on.

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I think I would rather call a weak or questionable result "Rh negative" and give them Rh negative blood and RhIG than call them positive and have a partial D that gets sensitized. We follow John Judd's recommendation and anything less than 2+ with anti-D in tube is called Rh negative. He recommened less than 3+ when testing using gel. (I am not talking about donor testing, just patient).

Not all reagents are the same, and they react with different D variants differently. You should see some variations in reactions with different reagents and methods.

There have been multiple articles about this, and most recommend dropping the weak-D test.

Linda Frederick

In this case, the patient sample was clearly positive in the tube method. Immucor Series 4 Anti-D she was 1+, and with the gamma clone Anti-D she was 3+, both at immediate spin. On the Galileo, she resulted D negative. Therefore, she is not, in fact, Weak D, (or Du) positive, she is D positive.

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  • 4 weeks later...

We have had the Galileo for over two years and had this same experience right off the bat! Our decision was to manually tube type the D unless there was already a manual result to verifiy the analyzer. Initially everyone huffed about this new rule, since we have automation, no one should have to verify the analyzer. But it is quite fast and we don't even think about it anymore.

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We have stopped performing weak D test for any patients except neonates. Due to different reagents and methodology one is going to find discrepancy from time to time depending upon institution's policy and testing method. We use Ortho PROVUE and have found same issue. We have a policy that if patient does not have have previous record and require blood transfusion we perform ABO/Rh confirm by another tech. Routine ABO is done by automation but confirm ABO/Rh by forward grouping only by tube method. This is when we find discrepancy some times. That is negative by automation and positive by tube at immediate spin. We are still not doing weak D test but to avoid givinh Rh Immune Globulin to potential Rh positive patients (immediate spin positive by tube test, neg by auto), we changed our policy to repeat Rh by tube method (IS only) for all Rh negative patients.

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  • 3 weeks later...

One of our clinical affiliates uses the Galileo, and they have encountered the same situation: Rh negative on the Galileo and 4+ Rh positive in tube testing.

Immunohematology published an article in 2005 about FDA approved anti-D antisera and partial D cells. The citation is:

Judd WJ, Moulds M and Schlanser G. Reactivitily of FDA-approved anti-D reagents with partial D red blood cells.Immunohematology Journal of Blood Group Serology and Education. Vol 21, 2005

It appears from their results that partial D patients could expalin the variability of reactions with different antisera, but these situations occur fairly frequently in our laboratory, perhaps too frequently to be explained by partial D.

If these situations DO represent partial D patients, wouldn't typing them as Rh negative make sense?

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One of our clinical affiliates uses the Galileo, and they have encountered the same situation: Rh negative on the Galileo and 4+ Rh positive in tube testing.

Immunohematology published an article in 2005 about FDA approved anti-D antisera and partial D cells. The citation is:

Judd WJ, Moulds M and Schlanser G. Reactivitily of FDA-approved anti-D reagents with partial D red blood cells.Immunohematology Journal of Blood Group Serology and Education. Vol 21, 2005

It appears from their results that partial D patients could expalin the variability of reactions with different antisera, but these situations occur fairly frequently in our laboratory, perhaps too frequently to be explained by partial D.

If these situations DO represent partial D patients, wouldn't typing them as Rh negative make sense?

In my opinion, No. Why would you want to call them Rh Negative when in fact they are not? By doing so, you are subjecting the patient to potentially unnecessary procedures - administration of RhoGam. I don't need to go into the potential (though small) risks associated with RhoGam, but there is also the cost associated with it. I do not believe it is ethical to change the basic principles of blood banking to fit the limitations of an automated instrument. The Galileo does not detect 1+ or mixed field reactions. (Section 9 -7 of the Users Manual)

Typing everyone who reacts less than 1 or 2+ on immediate spin (as one paper has suggested) as D negative, seems to be a "work around". It would make just as much (and save money) to simply do away with D testing and call everyone D Negative. Except in donor centers, of course. :cries: Anyone who has been in blood banking for a while knows that old soldiers from WWII are all "O Negative". That's what their dog tags said. That too, was a work around. Just err on the safe side and call them all O Negative.

It seems we are digressing in bloodbanking. I can't believe I'm seeing the day where educated professionals are calling macroscopic reactions, 1 to 2+ upon immediate spin, "negative". You have an antigen-antibody reaction taking place in that tube - what does that tell you? What if you took that anti-D tube that tested 1+ at immediate spin all the way through AHG and got a 3+ or 4+? Then would you call it a partial or weak D, or would you call it D Positive? :confused:

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  • 11 months later...

We repeat in tube any Rh negative from the Galileo with no history or a history of Rh positive. I agree with the frustration of having to manually follow up on your automation. You only have two choices when the automation has short comings: follow up manually or do away with that particular automation. I don't think there are any perfect instruments out there, but the Galileo seems to have more than its share of problems.

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For our testing on the Galileo, we also have previous patient history; either a historic type or if the patient is new, a type check before the sample is placed on the Galileo. If someone turns up Rh negative on the Galileo, the sample is repeated on the bench with the Weak D in mind. We have seen this frequently enough, that we now have a code that we add to our LIS that alerts our techs that the patient is a historic weak D and the ABO testing is then done manually. The Immucor D4 reagent is suppose to pick up weak D's better, but we know from our experience that it misses weak D's.

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I totally agree with this. My hospital discontinued 'weak D' testing long ago after following AABB recommendations. I also agree that I'd much rather result 'Rh negative' and give Rh negative blood rather than call someone Rh positive and then give Rh positive blood and then they become sensitized. To my knowledge, and also according to our reference laboratory, if you are a donor facility the weak D test is done but if you are a facility whose focus is giving blood to patients the weak D test should be eliminated......

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I don't think this is an issue strictly with automation - it has more to do with monoclonal anti-D reagents that are on the market now.

Previously, the anti-D reagent we were all using was human origin and most likely included antibodies to several epitopes of the D antigen. Now we are all using monoclonals that have reactivity to one of the epitopes on a large antigen. Each company has a proprietary monoclonal line, sometimes several. That's why Immucor has 2 anti-Ds (series 4 and 5) on their instruments, but the manual bench reagent is a blend (series 3 and 4). Ortho also has a blended monoclonal for manual but a single monoclonal for the cards. The end result is that there are a lot more "partial Ds" out there than previously thought. Are they all "D pos"? Probably. I know this doesn't really help in what to do with them, but it's an explanation. The manufacturers are aware - there was a session at AABB in October. To change reagents on the instruments requires re-applying for FDA clearance. Not quick.

There is another player on the reagent market - Quotient (formerly Alba in Europe) that has 3 or 4 different Anti-D reagents.

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