Weak D Testing Policy

[cinbb]

A question for all transfusion services.

Do you perform weak D tube testing for all prenatal patients (no previous history) presenting as Rh negative by MTS gel ABD Reverse Cards?

If the answer is yes, how many have you documented?

Thanks!

[jlemmons]

We only do weak D testing on Rh negative babies of Rh negative moms. And we actually do it on the Provue using Anti-D as the serum and the cord blood as the cells and performing an AHG crossmatch. I believe that AABB only actually requires Weak D testing on Rh negative units after they are drawn from the donor. We have had a fair number of moms who test at another lab, who use only tube typing, come to us for delivery and when we test them on the Provue, they test as Rh positive. We will tube type them and weak D test them and they have always tube typed as Rh neg Weak D positive. Now explaining to the doctors why we are calling the patient they know as Rh negative Rh positive is an interesting experience.

[bbville]

Weak D testing done only on Rh negative babies of Rh negative moms. We do call D testing by gel of 2+ or less Rh negative for RhIg candidates.

[Deny Morlino]

We do call D testing by gel of 2+ or less Rh negative for RhIg candidates.

Can anyone tell me the basis for this practice? I have come across references to the same practice in other posts (referring to automation of som sort I think) and do not recall MTS having this practice recommended anywhere. Curious as much as anything.

[vilma_mt]

Performing weak D testing on pre-natal patient is unnecessary. Weak D testing on baby's blood to determine if mom is a candidate for Rhogam is necessary. You may want to look into 'what if your D testing reaction is <2+', specially if you are using a monoclonal blend Anti-D. Weak Ds and partial Ds although can be considered not a candidate for Rhogam can still ellicit an immune response and therefore need Rh neg blood or RhIg. When in doubt it is far safer to give Rhogam than deal with the complications of not giving it. However, when performing an FetalBleed Screen with Anti-D reagent you may want to perform weak D testing as a control. Rh Pos maternal blood would give a 'false positive' result.

[vilma_mt]

Performing weak D testing on pre-natal patient is unnecessary. Weak D testing on baby's blood to determine if mom is a candidate for Rhogam is necessary. You may want to look into 'what if your D testing reaction is <2+', specially if you are using a monoclonal blend Anti-D. Weak Ds and partial Ds although can be considered not a candidate for Rhogam can still ellicit an immune response and therefore need Rh neg blood or RhIg. When in doubt it is far safer to give Rhogam than deal with the complications of not giving it. However, when performing an FetalBleed Screen with Anti-D reagent you may want to perform weak D testing as a control. Rh Pos maternal blood would give a 'false positive' result.

correction: Weak Ds and partial Ds although can be considered not a candidate for Rhogam can produce Anti-D and therefore need Rh neg blood or RhIg.

[BloodBank]

We perform weak D test only for cord blood of Rh negative (ProVue) mom. For all other patients including prenatal are resulted as negative or positive resulted by ProVue.

[Steven Jeff]

correction: Weak Ds and partial Ds although can be considered not a candidate for Rhogam can produce Anti-D and therefore need Rh neg blood or RhIg

It has always been my understanding that patients who are weak D do not produce anti-D and can be transfused Rh(D) positive blood. Partial D's should be treated as Rh(D) negative

Regards

Steve

:confused:

[Malcolm Needs ☆]

correction: Weak Ds and partial Ds although can be considered not a candidate for Rhogam can produce Anti-D and therefore need Rh neg blood or RhIg

It has always been my understanding that patients who are weak D do not produce anti-D and can be transfused Rh(D) positive blood. Partial D's should be treated as Rh(D) negative

Regards

Steve

:confused:

No, sorry Steven, but weak D individuals have now been described who have produced a true alloanti-D (albeit that the anti-D is weak). Joyce Poole was one of those authors, so I'm not going to argue with her!!!!!!

That having been said, it is still convention to treat them as RhD Positive as recipients, but for the more unusual weak D types, I would always check with Rhesusbase (Franz Wagner's website).

:o:o:o:o

[Steven Jeff]

Thanks Malcolm, I don't mind being corrected, and as you say my comment was based on the convention of treating weak D patients as Rh(D) positive. That said I think we had one this week on a gentleman in his late 70's, I didn't refer on to you Malcolm as I know you respond by saying why!!! and other expletives!! However, I advised my colleagues to treat him as Rh(D) negative - patient on Chemo and undergoing regular RBC transfusions and three adult doses of platelets this week. So you could say I went against convention on this patient.

Steve

:)

[Malcolm Needs ☆]

Thanks Malcolm, I don't mind being corrected, and as you say my comment was based on the convention of treating weak D patients as Rh(D) positive. That said I think we had one this week on a gentleman in his late 70's, I didn't refer on to you Malcolm as I know you respond by saying why!!! and other expletives!! However, I advised my colleagues to treat him as Rh(D) negative - patient on Chemo and undergoing regular RBC transfusions and three adult doses of platelets this week. So you could say I went against convention on this patient.

Steve

:)

I am exceedingly glad that you didn't refer this gentleman to us, but I have to say that I disagree with giving him D Negative blood and components (WHICH DOES NOT MEAN THAT YOU ARE WRONG)! This is why.

Here we have a male patient who is in his late 70's. Obviously, I do not know if he is weak D or Partial D, but he is not going to become pregnant, and so it does not matter whether or not he produces an anti-D.

In addition, he is on chemotherapy, which means that his already age-weakened immune system is going to be even more weakened by this chemotherapy. Therefore, even if he is a partial D, he is less likely than most patients to produce an anti-D.

If he does produce an anti-D, then I would switch to D Negative blood and components.

BUT THIS IS ONLY MY OPINION.

:redface::redface:

[AMcCord]

Can anyone tell me the basis for this practice? I have come across references to the same practice in other posts (referring to automation of som sort I think) and do not recall MTS having this practice recommended anywhere. Curious as much as anything.

This is a recommendation from Dr. W John Judd. The blood bank at U. Michigan, Ann Arbor (under Dr Judd) has done a lot of research/work with gel technology since it came out in the US. Based on the work they did, that's how they decided to name 'em when they saw 'em (weakly reacting Ds that is). If you read up on testing for the D antigen, you will see Dr Judd's name all over journal articles and AABB Technical Manual suggested reading.

[rravkin@aol.com]

I am exceedingly glad that you didn't refer this gentleman to us, but I have to say that I disagree with giving him D Negative blood and components (WHICH DOES NOT MEAN THAT YOU ARE WRONG)! This is why.

Here we have a male patient who is in his late 70's. Obviously, I do not know if he is weak D or Partial D, but he is not going to become pregnant, and so it does not matter whether or not he produces an anti-D.

In addition, he is on chemotherapy, which means that his already age-weakened immune system is going to be even more weakened by this chemotherapy. Therefore, even if he is a partial D, he is less likely than most patients to produce an anti-D.

If he does produce an anti-D, then I would switch to D Negative blood and components.

BUT THIS IS ONLY MY OPINION.

:redface::redface:

Hey Malcolm,

I'm reading the posts here and seeing all of this bold lettering and letters in red and I'm not sure why. I have to say that given this patients situation I would disagree with giving Rh-Pos blood for therapy because why potentiate an additional problem with an already complicated situation. If the patient were exanguinating Rh-Pos for sure. I understand where you are coming from; it is just as easy to change to Rh-Neg PC's when issuing therapeutic PC's for transfusion and I also understand the associated inventory issues; but we are not speaking of large volumes here, so I think that it is best for the patient to give PC's that would not potentially incur any additional complications. :)

[Steven Jeff]

Thanks rravkin for yout input, however that doesn't mean I don't agree with Malcolms comments. I have taken a conservative approach with this gentleman, I have no idea whether he is a weak D or partial D. His diagnosis is that of small cell carcinoma of the lung. As you say rravkin I have no wish do add to his problems, but how likely is he to produce an anti-D?

Steve

:)

Edited April 10, 2010 by Steven Jeff
wrong word

[rravkin@aol.com]

Thanks rravkin for yout input, however that doesn't mean I don't agree with Malcolms comments. I have taken a conservative approach with this gentleman, I have no idea whether he is a weak D or partial D. His diagnosis is that of small cell carcinoma of the lung. As you say rravkin I have no wish do add to his problems, but how likely is he to produce an anti-D?

Steve

:)

Hey Steve,

Thank you for your response. I agree with you and Malcolm that the chances of this patient developing an allo D are highly remote. However, this patient's condition is also somewhat remote and unless untilizing O Neg PC's for therapeutic transfusion was going to deplete the O Neg PC inventory and/or there would be a significant difference in cost why take the chance of producing yet another complication. You and Malcolm would have to agree that the very best PC product for this patient is O Neg, IRR, and CMV-Neg (dispite the potential redundancy).:)

[Malcolm Needs ☆]

Hey Malcolm,

I'm reading the posts here and seeing all of this bold lettering and letters in red and I'm not sure why. I have to say that given this patients situation I would disagree with giving Rh-Pos blood for therapy because why potentiate an additional problem with an already complicated situation. If the patient were exanguinating Rh-Pos for sure. I understand where you are coming from; it is just as easy to change to Rh-Neg PC's when issuing therapeutic PC's for transfusion and I also understand the associated inventory issues; but we are not speaking of large volumes here, so I think that it is best for the patient to give PC's that would not potentially incur any additional complications. :)

By the use of bold, coloured, upper-case letters I was trying to emphasise that my post is just matter of opinion - there is no correct or incorrect answer in this case.

It certainly is not just a question of using up the D Negative inventory, although that does come into it. My argument is that there is little or no chance of this gentleman making an alloanti-D in the first place, and so the use of D Positive blood would not compromise his clinical condition. That having been said, the use, particularly of D Negative platelets, were they are not required, does deplete the stocks substancially. D Negative platelets are made either of pools of donors platelets, or from individal donors giving by thrombopheresis. Platelets are rarely given as single units, and so there is almost always a shortage of D Negative platelets.

If this gentleman has not yet been primarily immunised, it should take more than the volume of red cells remaining in a unit of platelets to cause such an immunisation (if, indeed, he could be immunised against the D antigen in the first place), and so there is little or no danger to him by exacerbating his condition by giving D Positive platelets, whilst this would leave more D Negative platelets for those really in need.

All of that having been said, I still say that I would also give D Positive red cells with a clear concience.

:):)

[Steven Jeff]

Thanks Malcolm, I will check tomorrow the Rh status of the platelets transfused and review. With respect to the red cells, as a low volume transfuser of blood coupled with the need to keep O Rh(D) negative emergency blood at three sites we are often grateful for a patient to transfuse them too prior to expiry. However, I accept your well reasoned arguement for transfusing Rh(D) postive blood.

Regards

Steve

:)

[rravkin@aol.com]

By the use of bold, coloured, upper-case letters I was trying to emphasise that my post is just matter of opinion - there is no correct or incorrect answer in this case.

It certainly is not just a question of using up the D Negative inventory, although that does come into it. My argument is that there is little or no chance of this gentleman making an alloanti-D in the first place, and so the use of D Positive blood would not compromise his clinical condition. That having been said, the use, particularly of D Negative platelets, were they are not required, does deplete the stocks substancially. D Negative platelets are made either of pools of donors platelets, or from individal donors giving by thrombopheresis. Platelets are rarely given as single units, and so there is almost always a shortage of D Negative platelets.

If this gentleman has not yet been primarily immunised, it should take more than the volume of red cells remaining in a unit of platelets to cause such an immunisation (if, indeed, he could be immunised against the D antigen in the first place), and so there is little or no danger to him by exacerbating his condition by giving D Positive platelets, whilst this would leave more D Negative platelets for those really in need.

All of that having been said, I still say that I would also give D Positive red cells with a clear concience.

:):)

Hey Malcolm,

I hope that you are feeling alot better; I'm guessing that you are . With respect to platelets I fully agree. I guess it is always best to keep our options open. But I can tell you that I have encountered patients like this and I have given the Rh-Neg PC product because there is no question, no possibility, of developing an antibody (not withstanding the inventory issue); and I have practiced under management that promoted this practice. :)

[adiescast]

We actually end up gving D negative products to this type of patient because we do not routinely perform weak D typing. I absolutely agree with your argument, Malcolm. It just doesn't work with our process.

[Steven Jeff]

Hi adiescast, I don't have the ability to do weak D testing either. My assumption of a possible weak or partial D is based on the reactions against the two anti-D's in the Ortho ABO card that we use. One was weak and the second negative. However, as the patient is male and 81 years old, do we need to know whether he is a weak or a partial D? I am almost certain that if I referred this to Malcolm's lab he would give me an ear bashing!!!! or point out the errors of my ways, and rightly so.

Regards

Steve

[Malcolm Needs ☆]

Hi adiescast, I don't have the ability to do weak D testing either. My assumption of a possible weak or partial D is based on the reactions against the two anti-D's in the Ortho ABO card that we use. One was weak and the second negative. However, as the patient is male and 81 years old, do we need to know whether he is a weak or a partial D? I am almost certain that if I referred this to Malcolm's lab he would give me an ear bashing!!!! or point out the errors of my ways, and rightly so.

Regards

Steve

A genlte soul like me - as if!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

:giggle::giggle:

[MAGNUM]

We perform a weak D on all patients without previous histories who test negative on the Gel. Babies are tested for the weak D also. All OB patients who test as Rh negative have a weak D performed irregardless of their history. As to how many, we do approximately 15 OB patients a day with about half having no previous history.:cool:

[kmh76]

We do weak D testing only on neonates 4 months old or less. All our D negative prenatals are given RHIG @ 28 weeks and if applicable after delivery. We have had 3 cases of weak D positive patients not getting RHIG and developing Anti D. We currently have a prenatal that another hospital typed as A Negative Weak D positive. She now has an Anti D. We sent her out for molecular testing and she is a partial D category 6 capable of producing Anti D which can cause fetal fatalities. This is the 3rd patient in 6 years we have had like this. That is why we do not do weak D testing on prenatal patients. The results of not getting Rhig can be devistating!

[clmergen]

Wow, our partial D patients with Anti-D tend to test as 4+, they don't need weak D testing at all.

[Malcolm Needs ☆]

Wow, our partial D patients with Anti-D tend to test as 4+, they don't need weak D testing at all.

Hmm, not sure about that. Some Partial D types (e.g. Partial D VI type 4) give very weak reactions with even the best direct agglutinating monoclonal anti-D reagents.

:confused::confused: