Rh Interpretation Policy at your institution

[goodchild]

I realize the topic of Rh-discrepancies has been oft-discussed on these forums but I wanted to get an idea of what kinds of different policies are out there. A recent incident has brought this issue to a higher level of attention and we are looking at revising our current policy but before we do so, we'd like to find out how many other institutions have adopted something similar so we could feel comfortable that we'd fall under the umbrella of 'Generally Accepted Practice Standard.'

 

A prenatal patient was typed at an outside facility on a Galileo and found to be Rh-negative.

When the patient came in to deliver they were considered Rh-positive on the Ortho ProVue (2+ reaction).

We had no previous history on the patient so a second specimen was drawn and was also Rh-positive on the Ortho ProVue. (2+ reaction).

Our current policy says for women of childbearing age perform tube testing when anti-D is 1+ on ProVue. If tube testing is negative report Rh negative and if any degree positive report Rh positive with a comment that RhIg is at physician's discretion.

 

I don't think this is sufficient; I think we should look at 2+ gel reactions. I'm also concerned with the report of Rh-positive and a comment about RhIg administration. From a physician perspective, how do we know they are even seeing this comment to make the decision to administer RhIg? (the comments issue has been a long topic of debate through all sections of the laboratory, certain lab results show up in the EMR as SEE COMMENT specifically because of this) Partly based on recommendations from http://www.ncbi.nlm.nih.gov/pubmed/18067505.

 

There are definitely problems associated with changing the policy; how do we handle patients who we have previously typed as Rh-positive, change their blood type? Is it inappropriate to get positive anti-D results but report Rh-negative, will the techs or physicians be confused? Are we wasting our time/energy on something that isn't really worth it?

 

We're very curious to see how other institutions have handled this with the new anti-D reagents and testing platforms that are out there today.

[galvania]

I can't really fill in the questionnaire because the Swiss guidelines don't fit into any of those categories.  In Switzerland, patients are to be tested with 2 monoclonal anti-D reagents, at least one of which does not detect DVI.  If they are both negative the patient is treated as negative, if they are both 'properly' positive, then the patient is treated as positive.  If one is positive and one is negative, then the patient is considered as being a probable partial D and further investigations are carried out to ascertain which partial D is present.  The patient, regardless of age or sex, is treated as a D negative.  If both results are weak, then the patient is considered as being a probable D weak.  The way they are handled depends on age and sex.  A man (unless transfusion-dependent) is treated as D+, regardless of age, as is a woman who is past child-bearing age (defined as 50).  A woman of child bearing age, or anyone who is transfusion-dependent is genotyped to ascertain the D variant.  If found to be Dweak types 1, 2 or 3, they are considered as D+; any other type of Dweak, and of course partial D is to be treated as D Neg. 

Of course, this still misses partial Ds that react strongly positive with all (or most) anti-D reagents (for example DIII, DIV, DNB) - so of course, any apparant D+ with an anti-D would also be genotyped.

[goodchild]

Thanks for your detailed explanation Anna.

[Malcolm Needs ☆]

We are almost identical to Anna in the Uk.

[goodchild]

If I may ask, what is a proper positive? >1+ or >2+ ?

[galvania]

Well that depends on your numbering system.  If you have a numbering system that goes from 1-4, with 'half-points' inbetween, a proper positive is a 3+-4. In Bio-Rad (DiaMed) gel, that means that you have a really got line at the top of the gel, maybe with just a little bit of a shadow underneath.  In tube, that means complete agglutination

[AMcCord]

At UMich under Dr J Judd, a large study on anti-D reactions with gel was done in the earlier days of gel in the U.S. They concluded that anything less than or equal to 2+ by gel was suspect for weak or partial D. My poor memory thinks that the study was published in Transfusion at the time.

 

We use an Echo (2 anti-Ds) plus use a third anti-D for tube testing. If any one of the anti-Ds is less than 2+ we call the patient Rh negative and transfuse accordingly under the assumption that the patient's type is a possible weak or partial D. This is actually a pretty small number of people, so it's not sucking up the Rh negative blood supply. Someday...when molecular testing is cheaper...we will have them checked out so that we know for sure. If the patient was previously typed as Rh positive but is now called Rh negative we send a letter to the physician which explains some of the issues with Rh typing and why we are 'changing' the patient's type.

[Mabel Adams]

• 1. For all patients: for specific low anti-D reactions report Rh-negative with an explanatory comment

• I would have chosen the above but we will still turn out cord bloods as Rh positive so the mom will get RhIg appropriately.  We haven't formalized our policy yet but are leaning toward the options I have described and have been doing it on a case by case basis.

[Mabel Adams]

This is a comment that we have started entering on patient's with weakly reactive D's that we want to call negative.

 

Rh (D) type is weak and atypical.  As a blood donor this patient would be considered Rh positive; as a recipient or obstetric patient the patient should be considered Rh negative.

 

We had two patients who were D+ that made anti-D that we sent out a couple of years ago and they came back as Weak D Type 1 & 2 (using the Quotient/Alba partial D kit) who are not supposed to make anti-D at all.   They both typed weakly positive at IS testing--something less than 2+ anyway.  We had transfused one of them a few years before with D+ blood.

[galvania]

We had two patients who were D+ that made anti-D that we sent out a couple of years ago and they came back as Weak D Type 1 & 2 (using the Quotient/Alba partial D kit) who are not supposed to make anti-D at all.   They both typed weakly positive at IS testing--something less than 2+ anyway.  We had transfused one of them a few years before with D+ blood.

 

Hi Mabel

I don't think the Alba Partial D kit can tell you what type of D weak you have - it only distinguishes between different types of Partial D.  I would not be happy about classifying any weak D without carrying out a proper invesitgation at the molecular level.

On the other hand, several cases of AUTO-anti-D have been reported, I believe - so if you do get back a report on a patient with weak D type 1 or 2 with a weak anti-D, you do need to check this.  You should also check that the apparent anti-D is not really an anti-LW.

anna

[Malcolm Needs ☆]

Agreed Anna, although, just to muddy the waters further, before she retired, Joyce Poole did tell me of a very few cases of Weak D Type 1 and 2 making genuine alloanti-D.

[galvania]

Agreed Anna, although, just to muddy the waters further, before she retired, Joyce Poole did tell me of a very few cases of Weak D Type 1 and 2 making genuine alloanti-D.

Thank you for that Malcolm.  I had not heard that.  Were those cases published?  It would make very interesting reading.  (OK - I know!  I DO read novels too)

[AMcCord]

 

• 1. For all patients: for specific low anti-D reactions report Rh-negative with an explanatory comment
• I would have chosen the above but we will still turn out cord bloods as Rh positive so the mom will get RhIg appropriately.  We haven't formalized our policy yet but are leaning toward the options I have described and have been doing it on a case by case basis.

 

 

We qualify our cord blood results reported as Rh negative with additional test information - weak D testing results (such as negative, positive by weak D testing) or comments regarding possible variant D. We also include a 'test' result on cord blood panels which states whether or not mom is a candidate for RhoGAM based on the cord blood results, which she is if any reactivity is detected with anti-D. It is blood bank's responsibility to follow up on all cord blood testing to make sure that moms who need RhoGAM are offered RhoGAM.

[cthherbal ☆]

We require a 2nd specimen, and always test it by tube method (primary method is Provue or manual gel). This way we pick up discrepancies and transfuse with Rh neg appropriately. I was considering the Quotient D panel but given we only have sent 1 pregnant patient sample in 3+ years for molecular D testing, I am not sure it's worth the expense, or if it will be necessarily helpful. Anyone using it that have found it worthwhile?

[Malcolm Needs ☆]

Anna, I haven't forgotten your request, but have been up to my eyeballs (and way beyond) in setting exams, writing model answers, marking schemes, writing an obit, recruitment problems, HR Disciplinary problems, extended working hours problems and other problems, (poor excuses, I know), but will get back to you.

[Malcolm Needs ☆]

Hi Anna,

 

These are some references, as requested:

 

Beckers EAM, Ligthart PC, Overbeeke MAM, Maaskant PA, van Rhenen DJ.  A patient with weak D type 1 and anti-D: auto or allo.  Vox Sanguinis 2004; 87 (Suppl. 3): 75 (abstract).

 

Roxby D, Coloma M, Flegel WA, Poole J, Martin P, Abbott R.  Observation of anti-D after D-positive transfusion in an individual with weak D type-1 phenotype.  Vox Sanguinis 2004; 87 (Suppl. 3): 77-78.

 

Daniels G, Poole G, Poole J.  Partial D and weak D: can they be distinguished?  Transfusion Medicine 2007; 17: 145-146.

 

Pelc-Klopotowska M, Guz K, Walaszcyk A, Orzinska A, Michalewska B.  Weak D type 2 patient with allo anti-D.  Vox Sanguinis 2010; 99 (Suppl. 1): 367 (abstract).

 

Vege S, Fong C, Lomas-francis C, Nickle P, Horn T, Delaney M, Meny G, Westhoff CM.  Weak D type 2 and production of anti-D.  Transfusion 2011; 51 (Suppl 3): 41A (abstract).

 

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

 

Happy reading!

[Mabel Adams]

I looked back at the records and both my weak D patients were verified with molecular testing.  At least one of them was not an exact fit for type 1 or 2 (whichever she was) but was closer to that than anything else.  One case is pretty thoroughly written up here on the site somewhere from a couple of years ago.

[cbaldwin]

Hi Anna,

 

These are some references, as requested:

 

Beckers EAM, Ligthart PC, Overbeeke MAM, Maaskant PA, van Rhenen DJ.  A patient with weak D type 1 and anti-D: auto or allo.  Vox Sanguinis 2004; 87 (Suppl. 3): 75 (abstract).

 

Roxby D, Coloma M, Flegel WA, Poole J, Martin P, Abbott R.  Observation of anti-D after D-positive transfusion in an individual with weak D type-1 phenotype.  Vox Sanguinis 2004; 87 (Suppl. 3): 77-78.

 

Daniels G, Poole G, Poole J.  Partial D and weak D: can they be distinguished?  Transfusion Medicine 2007; 17: 145-146.

 

Pelc-Klopotowska M, Guz K, Walaszcyk A, Orzinska A, Michalewska B.  Weak D type 2 patient with allo anti-D.  Vox Sanguinis 2010; 99 (Suppl. 1): 367 (abstract).

 

Vege S, Fong C, Lomas-francis C, Nickle P, Horn T, Delaney M, Meny G, Westhoff CM.  Weak D type 2 and production of anti-D.  Transfusion 2011; 51 (Suppl 3): 41A (abstract).

 

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

 

Happy reading!

Thanks Malcolm for these references.

 

How do countries with high frequencies of the D antigen handle weak D patients?  Are they more apt to treat weak D patients as D positive?  The frequency of the D antigen in Brazil is 92%, the frequency in China is near 100%, according to my Immucor Antigen Frequency chart.

 

There is an article in the April 2014 Transfusion written by a group of Brazilian researchers entitled "How do we identity RHD variants using a practical molecular approach?".  It describes an algorithm that simplifies molecular testing for D variants using just certain exons so that the process and cost is reduced.  It's an algorithm that can be modified for other countries, other populations....They tested patients with atypical D expression, including discrepancies or reactivity weaker than 3+ in D typing.

 

The authors state that in the Brazilian population it is important to differentiate between partial D and weak D in order to conserve stocks of Rh negative blood.  I assume that in Brazil weak D patients are treated as Rh positive....

 

Weak D policies seem to be different in populations with high frequencies of D.

 

Catherine

[jojo808]

We do our antibody screen/ identification testing with GEL. Our ABO/Rh testing is tested with the tube method. Except for blood donors, transplant patients, and fetal testing why would it matter if you are weak D or D variant? I mean I know it matters but in regards to transfusing red cells or Rhogam administration? We used to report weak D patients as Rh neg, Du pos.

 

We stopped testing for weak D several years back due to the amount of patients we tested for weak D (about 2-5 per year). Now, if a patient tests as D neg (tube) we result as Rh neg with the disclaimer: "According to current regulations, testing for weak D is no longer performed. This may result in a discrepancy between an Rh type done previously on this patient at this or other testing facility." (STD 5.13.2).

 

I've also read that weak D types have been reported to make Anti-D. That being said, I like the fact that we save time and $ by being more conservative. It also help that we do our blood type testing with Tube method. Well actually although blood typing with tube is definitely faster than Gel, I'm not sure if costs less.

[Mabel Adams]

The stupid D nomenclature problem again raises its ugly head.  I think we are mostly speaking here of patients who react weakly at IS with anti-D rather than those for whom a weak D test was performed.  Those who react weakly at IS are more likely to be of the classification weak D type 1 or 2, I believe.  These people are supposed to have the whole antigen so usually can't make the antibody.  Certainly modern reagents are formulated so that they do not pick up partial D category VI unless we do the antiglobulin D test.  This is good, because people with this partial D are more likely than some other sorts to make anti-D. Of course, gel is good at picking up 

as D pos patients who would not react without AHG in tubes with most older reagents. The Quotient/Alba tube anti-D picks up a lot of weaker ones too.

 

Shall we post a poll that asks how many of us will begin referring to the old "weak D test" (which once was the Du test) as the "antiglobulin D test" so that when we refer to type 1 or 2 weak D patients it doesn't imply that they reacted only at AHG?  Or maybe a poll of better suggestions than mine.

[krp]

Hello All,

 

This is a really great topic and what I'm focusing my SBB project on.  My position allows me to visit multiple Transfusion Centers, and everyone is doing it a little different.  There is definately not a standard practice.  If you get a chance, please complete my survey so that I can tally the hosptial practices out there.

 

https://www.surveymonkey.com/s/ZMDFSLB

 

Thanks!