Rh neg history in Tube - now Rh positive in Gel

[SBriggs]

I am working to create a protocol regarding patients that were typed as Rh negative by the tube method, but are now Rh positive in Gel. We have found this problem a handful of times recently from our own history and also due to prenatal testing that is being performed at another facility in town. Our current procedure states to give RhIg to individuals if their reaction with anti-D is <2+. I am not sold on this and we are seeing these patients are sometimes >2+ with anti-D anyway. Physicians still want RhIg because patients have had it in the past. . .

I am looking for advice from anyone who has encountered this problem or anyone who has insight.

Thank you.

[Malcolm Needs ☆]

Patients "changing" their RhD type was a common problem a few years ago, because many had been previously typed with human-derived polyclonal anti-D, which gave negative reactions, and were now typed with much more avid monoclonal antibodies.

It has become less common these days, but, as you say, it still occurs, but for different reasons.

That having been said, I would personally err on the side of giving anti-D immunoglobulin prophylaxis in such circumstances (unless you are very sure of what your anti-D clones will and will not detect), on the grounds that there have been very, very few cases where anti-D immunoglobulin has been blamed for a transfusion-transmitted infection (except those where the anti-D immunoglobulin was not appropriately tested) and, of course, there has been the odd case with a patient with a potent anti-IgA who has reacted, but such cases are far less costly, both in terms of money and individual angst, than a lady who produces an alloanti-D because anti-D immunoglobulin prophylaxis was not given.

Being sued can be extremely expensive.

[LaraT23]

Hello, I actually had this happen last week! One of our OB docs was none too happy so, we do all OB patients by tube and gel and then err on the side of the negative. I built in a canned text to explain briefly when there is a discrepancy. This helps as our deliveries are not always typed prebnatally here.

[Mabel Adams]

What we really need is a test that separates those that can make anti-D from those that can't since serologic typing doesn't really work 100%.

[Malcolm Needs ☆]

What we really need is a test that separates those that can make anti-D from those that can't since serologic typing doesn't really work 100%.

True Mabel; got any suggestions, because even molecular work can't do that??????!!!!!!!!!!!

[Rh-fan]

It is not completely 100% sure but with the 2+ or less rule is the easiest way. You wil not cover all Rh variants (specialy those with a high expression DIII, DIV), but when testing in a sensitive methode (gel) there must be something wrong with the antigen if the reaction is only 2+. Ofcourse there are also normal antigen with a weak expression but they will not be harmed when they recevie RhD neg blood or anti D Ig.

[AMcCord]

Hello, I actually had this happen last week! One of our OB docs was none too happy so, we do all OB patients by tube and gel and then err on the side of the negative. I built in a canned text to explain briefly when there is a discrepancy. This helps as our deliveries are not always typed prebnatally here.

We are also faced with the problem of some OB patients who have not had their prenatal types performed by us. We follow the 2+ rule, so needless to say, we are picking up a few patients over the course of a year who are reported as Rh neg, previously Rh pos. We recommend RhoGAM and it's up to the physician to decide whether or not they want to give it. They always have, so far, but they are unhappy about the whole scenario.

The medical director and I composed a letter that attempts to explain - briefly - why the Rh type 'changed'. This letter is sent out to the physician any time we have any Rh neg patient who was previously reported as Rh positive.

[Barbarakym]

We have a policy that when gel is not at least 2+ on D to go to tube. We do not do the old Du extended D testing except on apparently O neg babies of O neg moms. We do not call people O positive unless they are macro by tube D testing. Weak D people we still call Rh neg. we found after following AABB recommendation of the 90's by calling these patients pos that we gave at least 2-3 people a year anti D. You can not tell the difference at reg BB level between mosaics and weak Ds.

[Mabel Adams]

Right Malcolm, but I like us to have clear goals!

I wonder if we get more and more data including molecular results on these sort of patients whether we will eventually tease out enough information on who will make the antibody to make doing molecular testing on them more worthwhile--or maybe eventually lead to a test that can tell us if they can make anti-D.

[Mabel Adams]

AMcCord, any chance you could post your letter?

[Mabel Adams]

I built in a canned text to explain briefly when there is a discrepancy. This helps as our deliveries are not always typed prenatally here.

Could you share your canned text?

[AMcCord]

Here's my letter - such as it is. We wanted to keep it to one page and keep it uncluttered with 'technical Blood Bank stuff', which the physicians aren't generally interested in anyway. The explanation of the weakly reacting D antigen is not blood banker worthy, but it has been sufficient for the docs. The recommendations are based on Dr. Judd's SOPs for Rh typing in Judd's Methods in Immunohematology, 3rd ed., conversations with reference lab folks and some reading I've done about the newest work done with the D antigen. We choose to play it very safe.

[ATTACH]581[/ATTACH]

[Malcolm Needs ☆]

Brilliant letter!

[Malcolm Needs ☆]

Right Malcolm, but I like us to have clear goals!

I wonder if we get more and more data including molecular results on these sort of patients whether we will eventually tease out enough information on who will make the antibody to make doing molecular testing on them more worthwhile--or maybe eventually lead to a test that can tell us if they can make anti-D.

I doubt it very much. Certainly not in the foreseeable future, as papers are appearing more and more about new Weak and Partial D mutations all the time, and also papers about established Weak D mutations that, by the old definition, shouldn't be making anti-D.

What is more to the point, I hope not. It would put Reference nerds like me out of a job - and I have a wife, son, mortgage and alcohol bill to support!!!!!!!!!!

:devilish::devilish:

[DPruden]

Thanks for posting this letter. We have actually had this come up a number of times, maybe there is a large population of strange Rh patients in my area!

[LisaM]

We've had the opposite happen once or twice, where the gel testing was negative for "D", and it came up positive in tube during Du testing. The only reason that was picked up, was because we get samples sent in from other sites that pay us to do their prenatal type and screens, and they're sort of not with the program a little in the respect that they insist upon Du testing for all Rh negative's, so we have to recheck all negative-D's in gel, by tube and Du. Even though gel is pretty reliable, there's always the occasional exception!

[Rh-fan]

We've had the opposite happen once or twice, where the gel testing was negative for "D", and it came up positive in tube during Du testing. The only reason that was picked up, was because we get samples sent in from other sites that pay us to do their prenatal type and screens, and they're sort of not with the program a little in the respect that they insist upon Du testing for all Rh negative's, so we have to recheck all negative-D's in gel, by tube and Du. Even though gel is pretty reliable, there's always the occasional exception!

That sounds like RhD variant DVI. The cards are for testing patients (and will not detect DVI variants), when you do a Du typing you wille detect DVI variants.

For recepiants or prenatal diagnostics it is better to call them RhD negative (even better do not perform a Du test), when it is a donor or cordblood call them RhD positive.

Peter

[LisaM]

^^Thanks, Peter! Aside from opening a can of worms with the Du testing on this particular group of patients and not going with just the gel results, it's also wasteful, cost-wise, and redundant, because 99% of the time, they check through perfectly and agree with the gel. But, we have no choice but to do it this way, per order of the facilities we get the samples from. On our own patients, we don't do that, unless there's some problem/question with the gel.

[Deny Morlino]

Lisa,

Any possibility of your pathologist educating the ordering physician or lab regarding the reasons for not performing the Weak D protocol? Just a thought.

[LisaM]

Lisa,

Any possibility of your pathologist educating the ordering physician or lab regarding the reasons for not performing the Weak D protocol? Just a thought.

I wish, but I don't see it happening. We don't have anyone in our court as far as being a "higher up", that has an extensive knowledge of blood bank, or one enough to vouch for us in instances like this. The BB supervisor has other things on her plate, and I'm not sure if she plans to address this at all at some point, or if it's considered minor in the scheme of things.

[Rh-fan]

^^Thanks, Peter! Aside from opening a can of worms with the Du testing on this particular group of patients

I agree, but as my forum-name is telling, I do not agree on the fraise "worms" when you talk about the wonderfull world of variant RhD antigens. For me it is "The more RhD discrepancies the better". At this moment we do fetal DNA typing on all RhD neg women (27th week) and the amount of discrepancies is big, but stil I say "the more the better".

As one of my co-workers says "every mad-man his one stangeness".

Peter

[LisaM]

I agree, but as my forum-name is telling, I do not agree on the fraise "worms" when you talk about the wonderfull world of variant RhD antigens. For me it is "The more RhD discrepancies the better". At this moment we do fetal DNA typing on all RhD neg women (27th week) and the amount of discrepancies is big, but stil I say "the more the better".

As one of my co-workers says "every mad-man his one stangeness".

Peter

True, but we aren't a reference lab where I work, and as much as I'd love to get into all the different, odd, and funky things that blood bank has to offer, we must keep it fairly basic, and simplistic for our customers. Not to mention, we don't have all the resources in the way of reagents and supplies to go much further than a certain point; we even send out our warm autos for work-up at the Red Cross because we don't have the means to neutralize them.

[jerriemc]

We have had this happen several times since we switched to gel. Our pathologist has us go by the old type and give them Rh negative blood. He feels the patient will be more at ease gettting the same blood type they got in the past. Granted most of our cases have been elderly patients.