15 hours ago, mollyredone said:

If we get a positive fetal screen we perform a weak D on the mother, and then look to see if the DAT is positive on the mother.  We would turn out the fetal screen as inconclusive and send the specimen out for a fetal Hgb F by flow.

Agree.

Unfortunately biology has a lot of gray.  There are an amazing number of genetic ways to be Rh positive or negative, for instance.  Not routinely testing for weak D is pretty accepted for transfusion recipients and pregnant people.  In the rare case that you have reason to run their D typing through AHG and find a positive, then you can give one dose of RhIG now and send them out for Kleihauer (and further elucidation of their Rh type, if desired).  Come May in the US, the American College of OB-Gyns plans to meet and accept a new standard that women with child-bearing potential who are found to be weakly reactive in the IS test with anti-D be genotyped for weak D types 1, 2 (and I think 3) to determine if they should be RhIG candidates.  At the AABB meeting they specifically said that they did not want us to go back to taking the test through AHG on specimens negative at IS.  Obviously we have to do this test to resolve problems at times.  You may want to get your computer reset to allow adults with a positive Weak D test to still be turned out as D negative.  Different for babies of course.

Maybe C and E typing would help? If the patient is C and E negative they're unlikely to be weak type 1, 2, or 3. The ethnic mix of you patient population would effect the usefulness of this strategy.

On ‎12‎/‎27‎/‎2015 at 11:07 PM, Mabel Adams said:

Unfortunately biology has a lot of gray.  There are an amazing number of genetic ways to be Rh positive or negative, for instance.  Not routinely testing for weak D is pretty accepted for transfusion recipients and pregnant people.  In the rare case that you have reason to run their D typing through AHG and find a positive, then you can give one dose of RhIG now and send them out for Kleihauer (and further elucidation of their Rh type, if desired).  Come May in the US, the American College of OB-Gyns plans to meet and accept a new standard that women with child-bearing potential who are found to be weakly reactive in the IS test with anti-D be genotyped for weak D types 1, 2 (and I think 3) to determine if they should be RhIG candidates.  At the AABB meeting they specifically said that they did not want us to go back to taking the test through AHG on specimens negative at IS.  Obviously we have to do this test to resolve problems at times.  You may want to get your computer reset to allow adults with a positive Weak D test to still be turned out as D negative.  Different for babies of course.

Mabel,

When you say "..weakly reactive.." are you refering to a ranking of 2+ or less?

Depends on whether you are testing with gel or tube, but I think all methods reacting 2+ or weaker would fall under this recommendation.  We have seen some patients who react 3+ in MTS gel, 1+ with Quotient anti-D in tube and negative with Immucor Gammaclone in tube.   

On 12/22/2015 at 8:00 PM, amym1586 said:

I just wonder if that will suffice to give one dose of RhIg to an Rh Neg Weak D pos mother of an Rh Pos baby.  Or if more testing is required.

I guess we are getting by with our procedure of them not being a candidate but I don't like that.

 

I still don't understand why there is so much gray area in blood banking. I feel like there should be way to do it and that is the way to do it. 

It can be, except when it isn't and without KB or flow you would never know - until the mother develops and antibody and you end up with HDN in the next pregnancy...

If we have a mother who types weak pos we send a sample out for molecular testing.  Just had our first one under the new policy and she is not a candidate for Rhig. 

On 12/30/2015 at 0:46 PM, KarenJ said:

If we have a mother who types weak pos we send a sample out for molecular testing.  Just had our first one under the new policy and she is not a candidate for Rhig. 

Can you let me know where you are sending your testing and how long it takes to get back?  Also - how clear is the report - clean answer or so much molecular verbiage you don't know what they mean?

Can I just remind everyone that whatever you do, you will NEVER provide anti-D to everyone who needs it and avoid giving to everyone who doesn't - at least not until someone comes up with a foolproof, cheap and quick way of genotyping.  Some partial Ds (who should receive anti-D) will be missed because they react exactly like normal D+, unless you are lucky enough to have a clone that misses the one epitope that they are lacking too.  Not all partials have decreased amounts of D antigen, and not all weak Ds can be sensitised to the D antigen.  This is 'grey areas' in spades.  The word 'simple' just does not exist when talking about Rh.

Rh_null individuals, of the amorphic type, express no Rh antigens of any sort.

SIMPLE Anna!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.................................but you are soooooooooooooo correct!!!!!!!!!!!!!!

 

 

So sorry!

The problem I'm running into is our OBGYN clinic sends out their prenatal Type and Screens to a reference lab that is doing Weak D's and reported the patients as Rh Positive.

I get them in the hospital for delivery, type them are Rh Negative and the floor will call back and say that doesn't match so we add on the Weak D to confirm.

 

This patient will NOT get an RhIG injection via our procedure.

I'm looking at my AABB Standards for Blood Banks and Transfusion Services. I can't see where it says a Weak D positive woman needs a RhIG in writing.  

First - I would verify that we drew the right patient and verify that our results are correct as reported - immediate spin results. I would also do the weak D test to confirm what the reference report is saying. That makes the discussion we may be having with the patient's doc about the discrepancy easier. Then we would report our results - Rh negative - and recommend RhoGAM (with a Kleihauer-Betke performed). This is the protocol for our facility. Until there is a published guideline for molecular testing results and who gets RhoGAM (which is going to be coming soon from the College of OB/GYN), if the patient is IS D negative, we recommend RhoGAM. Our house, our rules (our liability). I would take the results to the pathologist on call so that he/she is on top of things if the physician calls for a consultation, which they generally don't.

For the rare occasions that we've dealt with this, the OB/GYN docs have given the RhoGAM and a midwife refused it. If the provider declines to give RhoGAM, that is their perogative, however I would request that they document in the patient EMR that they have seen our Rh results and have declined to issue RhoGAM. And that's the end of it.

If we had a previous result on file for testing performed by us that was weak D positive, we would report it as Rh negative, previously reported as variant or weakly reactive D. I have sent a letter out in the past explaining why results for D testing can vary from lab to lab (or change from pos to neg here) that goes into a few details about the complications of D typing. (I'm sure their eyes glazed over reading it). All the medical staff currently with us have now seen that letter if they so desired.

Thankfully we are back to doing almost all the prenatal panels for the OBs we deliver.

12 minutes ago, AMcCord said:

First - I would verify that we drew the right patient and verify that our results are correct as reported - immediate spin results. I would also do the weak D test to confirm what the reference report is saying.

We do that first as well.

 

13 minutes ago, AMcCord said:

Then we would report our results - Rh negative - and recommend RhoGAM

 I like that!

 

Thank you so much for your feedback !

I will get back to this post on Monday, as I think I have a couple of things to say, BUT, I will say one thing immediately, and that is that if I gave a midwife my considered opinion as to whether the lady was D Positive, D Negative, Weak D, Partial D or DEL, and he or she ignored me and decided that he/she knew more about the Rh Blood Group System than do I, with particular reference to the D antigen, AND ignored my opinion as to whether anti-D immunoglobulin should or should not be offered to the lady, at the very first opportunity (when one of the ladies produced an immune anti-D), I would offer my services to her, for free, as an expert witness, and take the midwife for every penny (or cent) we could squeeze out of her.

To enjoy some of the complexities of the Rh antigen visit here: http://www.uni-ulm.de/~wflegel/RH/

 

Agreed Mabel; another wonderful site.

On 1/15/2016 at 1:49 PM, Malcolm Needs said:

I will get back to this post on Monday, as I think I have a couple of things to say, BUT, I will say one thing immediately, and that is that if I gave a midwife my considered opinion as to whether the lady was D Positive, D Negative, Weak D, Partial D or DEL, and he or she ignored me and decided that he/she knew more about the Rh Blood Group System than do I, with particular reference to the D antigen, AND ignored my opinion as to whether anti-D immunoglobulin should or should not be offered to the lady, at the very first opportunity (when one of the ladies produced an immune anti-D), I would offer my services to her, for free, as an expert witness, and take the midwife for every penny (or cent) we could squeeze out of her.

True to form, and having enjoyed a relaxing weekend, I have forgotten what I was going to say, however, two papers on the subject are a very worthwhile read.  These are:

Daniels G.  Variants of RhD - current testing and clinical consequences.  British Journal of Haematology 2013; 161: 461-470.

Sandler SG, Flegel WA, Westhoff CM, Denomme GA, Delaney M, Keller MA, Johnson ST, Katz L, Queenan JT, Vassallo RR, Simon CD.  It's time to phase in RHD genotyping for patients with a serologic weak D phenotype.  Transfusion 2015; 55: 680-689.

Essentially, both say the same thing, in that women who are Weak D types 1, 2 and 3 do not require anti-D immunoglobulin, whilst all other weak and partial types should be offered anti-D immunoglobulin - although, of course, you can't force them to accept it!  Also, if possible cffDNA should be used to predict the foetal D type (if possible) to see if the woman requires it or not - she may be carrying a D Negative foetus.

I think we are about to begin a big shift in this country. CAP and AABB issued a joint statement in Oct 2015 urging molecular testing. Once the American College of Obstetricians and Gynecologists comes on board with their guidelines - and apparently this is supposed to happen with their annual meeting this year - that should start the ball rolling downhill for OB cases at least. At that point we can start arguing that it is the standard of care and hopefully the insurance companies will start paying for it. The next very important step will be technology that makes the testing more accessible (a platform that is affordable in the hospital setting) and cheaper to do.

40 minutes ago, AMcCord said:

The next very important step will be technology that makes the testing more accessible (a platform that is affordable in the hospital setting) and cheaper to do.

I think that this could be some way off, as the technique and technology used for weak and partial D typing is very different to the "quick and dirty" (for want of a better way of putting it) technique and technology used for normal genotyping, where only certain exons are probed.  To genotype for all weak and partial D types, you would have to perform a complete RHD gene sequence - which is both time consuming and very expensive.

The suggested phase-in would be to genotype for type 1, 2, and 3. There is no recommendation at this point for the complete sequence. The treatment recommendation would be no RhoGAM for the type 1, 2 or 3 patient and give RhoGAM if the patient is anything else.

True, but the problem is that the mutations that are seen in these weak D types can also be seen in other weak and/or partial D types, and unless you do the full RHD sequencing, such mutations may be missed - mind you, having said that, they are rare.

AABB Technical Manual 17 ed pg 637

"Women with red cells that are clearly positive on the weak D test should be considered D positive and not receive RhIg"

That being said I guess there are many ways to define "clearly positive on the weak D test"

On ‎12‎/‎22‎/‎2015 at 9:56 AM, Malcolm Needs said:

No David.  Sadly, it was in the UK that the term "D^u" was first coined (the "^u" bit standing for unagglutinable) by the above mentioned Fred Stratton.  It was a very interesting paper, as was that by Race and Sanger.

 

We do not give anti-D immunoglobulin for Weak D types 1, 2 and 3, but do for all other Weak D types and, of course, for ALL Partial D types.

Thank you!  Our students always ask what the "u" stands for and I never knew.