D typing

[MHiggins]

We have recently switched from using the Ortho ProVue to the BioRad tango Optimo. With this, we have encountered some issues. The tango does not pick up Du on the routine ABO/Rh strip. The ProVue ABO/Rh card does. So, we have had a lot of discrepant Rh types since we have started using the tango. We use the Quotient D Blend as our serologic reagent, which does pick up Du at immediate spin, as well as Du & D6 at IAT. In the last week we have had two OB patients type as Rh negative both on the tango and at immediate spin with the Quotient D blend. On one patient, the nurse called and stated that the patient had a history of being Rh Positive in their prenatal workup that was done at another lab. On the other patient, their Rh type was not questioned until their Fetal Bleed Screen was performed and was macroscopically positive. Both were testing through IAT with the Quotient D blend and with the Ortho ABO/Rh gel card (manual method) and were found to be Rh positive.

I feel like when we run into these patients with discrepant types, we are chasing our tails testing by 3 methods to confirm their Rh type and am wondering if there is a better way/process? What does your facility do for routine D testing? What about Du testing? We typically only perform Du testing on Rh negative babies born to Rh negative mothers and of course when an investigation is needed like the above situations.

Any wisdom is great appreciated! TIA!

 

[Malcolm Needs ☆]

It's a bit late now, as I have been marking examination scripts all day, but I'll try to address your question tomorrow, if someone else has not given a satisfactory answer before then. 

[mollyredone]

Some labs may still do Du routinely on patients, unless maybe that was when she was a donor.  We just do immediate spin on all patients except newborns as you noted above.  If we have a positive FMH the first test we run is a Du on the mother.  We have had some Du positive results.  The FMH is not valid in this case, as it is also not valid for a Du positive baby with our test kit.  I would not want to report out a Du routinely on a mother, since she could still form anti-D. If we have a baby who is Du positive, we report it as negative (not wanting to change the type later in life) but enter the comment "Baby is weak D positive.  The mother should be considered a candidate for Rhogam prophylaxis. FMH results are not valid.  Please order a HGB FETAL if a fetal bleed is suspected.”

I could be wrong, but I wouldn't want to report out Du positive, calling the patients Rh positive, routinely.  If women start getting genotyped, as it is now being suggested, to find out if they can form anti-D (not types 1,2, or 3)  we could avoid some Rhogam and Rh negative units.

[Dansket]

2 hours ago, mollyredone said:

If we have a baby who is Du positive, we report it as negative (not wanting to change the type later in life) but enter the comment "Baby is weak D positive. 

Currently, to avoid any confusion amongst physicians, nurses and generalist blood bank staff, all patients are reported as either Rh Positive or Rh Negative.  Meditech is configured to automatically reflex Weak D test and Weak D control on newborns whose red cells do not react with anti-D in the A/B/D Monoclonal and Reverse Grouping Gel card on ProVue.  If the Weak D test is agglutinated and the Weak D control is not agglutinated, again on ProVue, newborns are classified and reported as Rh Positive without any disclaimer.

BTW, I thought the term "Du" was obsolete and had been replaced by "Weak D".

[Malcolm Needs ☆]

The problem, for me, in answering this question is that we do things differently in the UK, but there are one or two comments I would make (and probably make myself very unpopular in so doing).

Firstly, as Dansket says, the term "D^u" has been obsolete for many years now, and has ,indeed, been replaced by the term "Weak D".  Secondly, though, as there is no such thing as either "anti-D^u" or "anti-Weak-D", but only anti-D reagents that are capable of detecting a weakly expressed D antigen (be this a Weak or a Partial D), and so an individual cannot be described as either "D^u Positive" or "Weak D Positive".

BCSH Guidelines in the UK (Guidelines for pre-transfusion compatibility procedures in blood transfusion laboratories, Transfusion Medicine 2012; 23(1): 3-35) do not "encourage" testing for Weak or Partial D phenotypes, except in certain circumstances (for example, if the patient is female and 50-years-old or less, is the patient likely to become transfusion-dependent, is there an apparent anti-D present in the plasma of an apparent D Positive patient, is the individual donating blood, to name a few), but we are not encouraged to determine whether or not a cord blood expresses the Partial D^VI phenotype, as there is very, very little evidence that such cord blood has ever actually caused a mother to become sensitised (even though I think that I am correct in saying that the authors of the original paper on this were from the UK!).  The other reason that an anti-D that will detect the Partial D^VI phenotype is not encouraged in a Hospital Laboratory, even for testing cord blood, is that there is a danger that normal patients (as opposed to donors) may be tested with this reagent, and therefore may be wrongly defined (in our terms) as D Positive, rather than D Negative, meaning that females of child-bearing potential may be immunised against the D antigen.

[mollyredone]

13 hours ago, Dansket said:

BTW, I thought the term "Du" was obsolete and had been replaced by "Weak D".

I apologize.  I was just following the original poster's language.  We have Meditech and it does have weak D testing for babies-although Meditech still calls it Du!  Has that changed in your version of Meditech?  We do ABO/Rh in tube and do not perform weak D on anyone other than babies (or moms with positive FMH)  Therefore, we don't want to call a baby Rh positive with a weak D test if later in life we wouldn't perform weak D testing.  We report the baby as Rh negative.  But we do want to warn the physician that the mom is still a candidate for Rhogam.  Otherwise they would see, mom neg, baby neg, no Rhogam needed.  Does that make sense?

 

[mollyredone]

14 hours ago, Dansket said:

Meditech is configured to automatically reflex Weak D test and Weak D control on newborns whose red cells do not react with anti-D in the A/B/D Monoclonal and Reverse Grouping Gel card on ProVue.  If the Weak D test is agglutinated and the Weak D control is not agglutinated, again on ProVue, newborns are classified and reported as Rh Positive without any disclaimer.

It sounds like you would have to change the type of the baby from Rh positive to Rh negative if he/she came back in at a later time.  We wanted to avoid that.

[MHiggins]

Thank you all for the responses! I should also explain, I have only been in the field for 8ish years, BB supervisor for 4, and have only ever worked in a Transfusion Service at the hospital I am at now so the way things were already being done here is the only way I have known! With that being said, I do feel like there are a LOT of things that need "improved", this being one of them.

My senior techs are telling me that they have always reported patients who tested positive for Weak D (our system still calls it Du as well) as Rh positive. We ONLY test patients for Weak D if there has been some discrepancy or if they are a Rh negative baby born to a Rh negative mother. In the case of the infant testing, if we report them out as negative, they might not give the patient the RhoGam. And from I am gathering, giving all Rh negative mothers would not be an ideal process either? Also, what about these reagents that are detecting Weak D at immediate spin such as the Ortho Gel cards and the Quotient reagents? Is that a bad thing?

 I did recently attend the AABB Annual Meeting where I heard a lecture about these Weak D positive patients developing anti-D. I had not heard that before!! So, currently we are reporting these Weak D positive patients as Rh positive. Does anyone have a literary source about these developing anti-D that I can use to convince my director/pathologist that we need to change our process? 

Thanks again for all of the information! I am always learning and appreciate any input!

M

[Malcolm Needs ☆]

43 minutes ago, MHiggins said:

Does anyone have a literary source about these developing anti-D that I can use to convince my director/pathologist that we need to change our process? 

If you (or your Director/Pathologist) can get hold of Geoff Daniels Human Blood Groups.  3^rd edition, 2013, Wiley-Blackwell, and look at Table 5.5 on pages 197 and 198, he gives references for quite a few reports of both Weak D and Partial D phenotypes that have produced allo-anti-D.  It is not quite a comprehensive list, but it is not at all bad (as you would expect from anything written by Geoff!).

[Carrie Easley]

Our primary method is gel.  If we get =/< 2+ reactivity (on someone pregnant or with childbearing potential), we repeat with tube reagents to see if it reacts at IS.  If not, we incubate @ RT for 15minutes.   If tube reactivity is not 2+ or more, we tentatively call the patient Rh- and request an order for Rh genotyping from the physician.  The vast majority do come back as being a variant that can be treated as Rh+ for transfusion/RhIg purposes.  There have been a couple that we were told have the potential to make an anti-D. 

I uploaded one reference to the library under Educational Materials.  There was also a good article in Transfusion Volume 55, March 2015

[AMcCord]

We are currently doing types on the Echo and if the results with the anti-D reagents are not both 2+ or greater, we repeat the type by tube using the Echo's anti-D reagents and the anti-D (monoclonal blend) we use for routine tube testing. If the tube tests results are not all 2+ or greater, we call the patient Rh negative. We are not yet sending out these patients for molecular testing. Right now my medical director is not comfortable with recommending RhoGAM based on molecular testing results, so he doesn't want to send out for testing he's not going to use for treatment recommendations. I think we'll move in that direction, just not yet. These patients are treated as Rh negative for the purposes of transfusion and we recommend RhoGAM. If RhoGAM is needed, the patient must have a Kleihauer-Betke performed. Our patient population doesn't include very many of these individuals so we are not 'wasting' a bunch of Rh negative blood or RhoGAM.

Baby types are interpreted the same way. If the anti-D reagents are not reactive 2+ or greater, the patient is reported out as Rh negative. We include weak D testing results on the cord blood reports. The weak D can be reported as 'negative' or 'positive by weak D test'. So a baby with weak reactions with anti-D would be reported as Rh Negative, Positive by Weak D test. In addition, we would report 'Mother is a candidate for RhoGAM'. If baby has funky D results and mom needs RhoGAM, mom needs a Kleihauer-Betke. If the baby is Rh negative and the weak D test is negative, we would report 'Mother is NOT a candidate for RhoGAM'.  By reporting baby types this way, we don't have to change the Rh type later in life.

https://www.aabb.org/advocacy/statements/Documents/statement150722.pdf

I don't think my link above is going to work, but you can cut and paste it to find the article. This is the current thinking on the topic of Rh typing and OB patients. We treat all of our patients the same as we do the OBs. Towards the end of the article there is a small flow chart that indicates how the authors recommend that the results of Rh typing should be interpretated/handled. One of the authors (Connie Westhoff) has written the Rh chapter in the recent AABB Technical Manual so that's another easy reference point.

 

[mollyredone]

AMcCord said it better than I did, but that is how we do it too.

[Mabel Adams]

Since starting to use Quotient anti-D and Ortho gel ABD cards we have a little comment that we attach to such patients' reports that goes something like: "This patient has a weak and atypical Rh type.  Different labs may report different Rh type results.  As a donor she/he will be considered Rh positive.  As a recipient or obstetric patient she should be treated as Rh negative."  We are currently calling them Rh neg unless they react stronger than 2+--especially if they have childbearing capacity.  There are exceptions like if we have transfused a male as Rh pos in the past and he has made no antibody, then we might continue to call him Rh pos.

I wouldn't allow them the choice to do a Kleihauer instead of a fetal screen.  In the only cases I have seen that needed more than one dose of RhIG (absent some sort of trauma) there was absolutely no clue clinically.

We would change the baby's blood type to negative if they ever came back in needing transfusion.  I don't think we've had to yet.

[BBfuntimes]

On ‎12‎/‎6‎/‎2016 at 7:52 AM, mollyredone said:

I apologize.  I was just following the original poster's language.  We have Meditech and it does have weak D testing for babies-although Meditech still calls it Du!  Has that changed in your version of Meditech?  We do ABO/Rh in tube and do not perform weak D on anyone other than babies (or moms with positive FMH)  Therefore, we don't want to call a baby Rh positive with a weak D test if later in life we wouldn't perform weak D testing.  We report the baby as Rh negative.  But we do want to warn the physician that the mom is still a candidate for Rhogam.  Otherwise they would see, mom neg, baby neg, no Rhogam needed.  Does that make sense?

 

Meditech is built by the facility, so you should have the capability to call  "Du" anything you want in that test dictionary.  EMR IDs come as is, and I believe this one says "Weak D (Du)". 

[Malcolm Needs ☆]

I hate to say this, as it sounds so egocentric, BUT, as I said in my first ever post on PathLabTalk in 2009 (or, if it wasn't my first one, it was one of my first ones), if people used the correct nomenclature (as stated by the ISBT - and this INCLUDES the people who produce computer systems for Blood Banks (who seem to think that they are exempt from this kind of thing), this kind of problem would never happen.

Just saying!