Discrepant D typing results

[Dar]

We have been recently having discrepant Rh typing results, especially from Moms whose pre-natal testing was performed in another Lab. I have been asked to send a memo to the Medical Staff explaining how this could happen. I was wondering if anyone has already had to deal with this issue. I began to quote Chapt 13 of the Technical Manual, but I realized that the physicians probably would not want to read anything in this detail. Any physician memos circulating out there regarding D antigen typing & clones from various vendors???

[galvania]

From the way your posting reads it sounds as though these discrepant results are not that rare. If that is the case, are you sure the discrepancies are not due to problems in one of the labs rather than a large number of mums with weak D / partial D phenotypes?

[Malcolm Needs ☆]

We have been recently having discrepant Rh typing results, especially from Moms whose pre-natal testing was performed in another Lab. I have been asked to send a memo to the Medical Staff explaining how this could happen. I was wondering if anyone has already had to deal with this issue. I began to quote Chapt 13 of the Technical Manual, but I realized that the physicians probably would not want to read anything in this detail. Any physician memos circulating out there regarding D antigen typing & clones from various vendors???

You have my entire sympathy. This is a problem that has come to light much more particularly since the advent of monoclonal reagents and, come to that, molecular investigations.

I think that you are quite correct in thinking that most physicians would be unaware of the various machinations involved in the RhD gene and molecule, and trying to give them a really detailed explanation would be a waste of breath. On the other hand, a certain amount of "ego massaging" may not go amiss, and so I have tried to put together a short document that may, or may not be of use.

I attach it below, and if you think it would be useful (even if you edit it) please feel free to use it. If you think not, then no harm is done if you choose not to use it (even in an editted form).

I hope it helps in some small way though.

:D:D:D:D

Change of RhD Antigen Status.doc

[Dar]

Malcolm, I love your verbiage! I am definitely plagiarizing it! Thanks!

[YorkshireExile]

That document is very good Malcolm. I may have to edit it slightly (only slightly) for our linguistically challenged doctors, but I will definitely use it the next time the "D grouping" question arises in my hospital.

[SusanM]

Love it, Malcolm!

[KarenJ]

Thanks Malcom, I will hang onto that form for the next "discrepancy" I find.

[Mary**]

Your document is very well done, but I think it will be more info than doctors can handle. I saved it for future use. Thanks.

[Malcolm Needs ☆]

Your document is very well done, but I think it will be more info than doctors can handle. I saved it for future use. Thanks.

Believe me, that was deliberate!!

:devilish::devilish:

[KKidd]

We were faced with a situation where a patient received different Rh resultsfrom our facility and another one. We no longer test for weak D and she had tested as weak D positive at our place 10 years ago. After much anguish and trying to explain the situation, we added the follong comment to our ABO/RH results "Weak D (Du) testing is no longer performed in compliance with The Joint COmmission and AABB standards".

When we all performed tube testing and weak D, perhaps our results correlated better. Automation and monoclonal reagents have changed things quite a bit.

:confuse:

[adiescast]

I am getting the impression that many of the larger general reference labs perform weak D testing routinely, but the hospital transfusion services have stopped doing them routinely. We have also run into this problem. Our physicians have been pretty receptive to the explanation (a miracle!), but they are confused about the RhIg decision for weak D positive mothers.

[Dar]

Thanks for everyone's reply! We stopped performing weak D a few years ago without any issues. Let's face it, our industry has needed some healthy reagent competition for years. Now that we have it, the D antigen testing is a challenge. Not only is it the antisera, but the increase of methods / instrumentation that also feeds into this equation. I'm afraid that this issue will not be solved quickly, but at least I will be able to calm down my physicians...well, maybe....

[Malcolm Needs ☆]

I'm afraid that this issue will not be solved quickly, but at least I will be able to calm down my physicians...well, maybe....

That's what I like to see; a triumph of optimism over experience!!!!!!!!!!!!!!!!!!!!!!!

:excited::excited:

[profbaud]

Are you using Ortho's bioclone D reagent? It doesn't pick up all the weak D phenotypes like Immucor's Anti-D does. We see this discrepancy when we do retypes after putting the pt. specimen on the Provue. Then we end up doing a Du to confirm that the patient is Rh pos.

[RWOOD57]

We changed from Ortho to Immcor's Reagent. We have had several discrepant Rh histories.

[Dar]

Yes, we are using Ortho. We also used Immucor in the past. The staff have been advised not to change a blood type without supervisor approval, so that the physician can be alerted appropriately.

[margaretcox]

What do others do about patients that come to light (for whatever reason) as "only" weak/partial D? Do you treat them as Rh negative or positive for transfusion or RhIg purposes? (We treat as negative).

And, do you report them as negative, positive, or positive with a "weak" comment?

[adiescast]

We do the immediate spin D test. If it is negative, we call the person negative and give Rh negative blood. For RhIg, we leave it up to the physician to decide whether to give a weak D positive patient RhIg or not. (We do perform the weak D before we do a fetalscreen.)

[Dar]

If our immediate spin test is 1+ or less, we call them Rh negative and give them RHIG. We might put some sort of weak note in their history. If it is weak like this with Ortho, but was strong in our Immucor days, we do not change the blood type. We are now seeing 3 or 4+ reactions as immediate spins that have been called negative by the physician's reference lab. In that case, we leave it up to the physician to decide.

[L106]

This is getting messy, isn't it??

[Deny Morlino]

Yes very messy and very confusing for physician's offices as well.

[adiescast]

The sad thing is that the patient antigens haven't changed, just the reagents. Now we have to develop new paradigms for what is a potential partial D that could develop an antibody.

[jlemmons]

We have run into this problem when testing was done at a laboratory that does all of their typing by tube. We have found that the Provue is more sensitive in this area and we will get a D positive when the other laboratory did tube typing without doing weak D testing (because it is not required) and we get to explain that the patient is really D positive and does not need RhIg. We do give the RhIg if the physician is insistent on it.

[Juliane]

We tend to have any discrepancy in Rh type be resolved with supervisory involvement. Read your package inserts, some say partial D is detected, some don't. I was told by a vendor that if it DOES detect a variant like DVI, then they have to disclose it. If not, they don't have to mention it. That is confusing, because we are left to ASSUME.... Also, we confirm the type with two separate venipunctures in these cases before giving type specific (including RH). We add a comment to attempt to explain this to physicians, that the Rh typing is very weak and in some cases, we go on to recommend receiving Rh negative blood (child bearing age females) but to understand that these patients are considered Rh positive as blood donors. We are also considering sending letters to these patients to make them aware that at some facilities they may be considered Rh neg, and at others, Rh pos so they can be aware of this chance in differing blood types being reported.

Do any of you participate with the National Patient Antibody Registry? Subscribers data is there to share their histories. It is small but trying to expand. Based out of New Jersey I think now. Curious how this will impact that dilemma of differing Rh types.....

[donnalander]

The transfusion service I worked at followed the AABB technial manual Method 2.9 Test for Weak D, Interpretation If the facility chooses to perform the test for weak D, and the result is clearly positive, the blood should be classified as D+. It is incorrect to report such red cells as being "D-, weak D" or "D-, Du."

"Weak D" patients received Rh Positive blood; no RhIG was issued.