Is it possible for a pregnant patient to type D negative (no weak D testing performed), then at delivery type as 2+. I recognize this is likely either a tech error or a phleb error, but I was wondering if anyone knew of this happening?

Thanks

Teresa

Is it possible for a pregnant patient to type D negative (no weak D testing performed), then at delivery type as 2+. I recognize this is likely either a tech error or a phleb error, but I was wondering if anyone knew of this happening?

Thanks

Teresa

There could be several reasons, one is a large fetal-maternal hemorrhage. I suspect that since Weak D testing was not done and given a 2+ reaction with anti-D that patient is Weak D positive.

Who did the original type? If you are using Anti-D made by Ortho, it will not pick up weak D at immediate spin. If you are using Anti-D made by Immucor or Biorad, its a blend and will pick up some weak D's.

It has been noted in the literature that this has occured during pregnancy (D Neg going to D Pos - albeit weakly). Belinda Kumple (of the IBGRL) did a poster about this for a BBTS Meeting a few years back. I'm at home at the moment, but when I get into work tomorrow, where I have most of my Transfusion Science Journals, I'll post the reference.

As promised, although it is actually about the strengthening of the D antigen on another haplotype during pregnancy, it is still relevant.

Kumple K, Wreford-Bush T. Expression of the D antigen increases on R2r red cells during pregnancy. Transfusion Science 2010; 20 (suppl 1): page 30 (PO10).

I would guess that what you have is a very low grade Weak D that is now apparent by "normal" means.

I recognize this is likely either a tech error or a phleb error, but I was wondering if anyone knew of this happening?

Thanks

Teresa

I supposed that mostly clerc. or tech. error, the incidance of that O negative pregnant to produce anti D because she is actual patial D is very rare accorrding to AABB tech 17th edition>

One thing to consider also is the technique used by the technologists performing the tests. My first thought was that it is an Immucor/Orhto reagent problem. But if the same reagents are used and one technologist let the tube sit at room temperature for an extended length of time, that may change a negative reaction to a positive reaction. I have seen this with some weak Ds although going beyond 1+ is unusual.

Lots of ideas presented here.

Basically there are these possibilities and they all need to be considered/investigated:

1. Specimen from prenatal/previous testing was mislabeled, e.g. someone else's blood.

2. Tech made an error somewhere along the testing path or recording during the previous testing.

3. Tech made an error somewhere along the testing path or recording during this testing.

4. Sample 'today' is the 'wrong' patient ... misdraw, misidentification or maybe another patient who is not who she says she is (e.g. using someone else's insurance card, it happens a lot in my area).

5. You are picking up a large fetal-maternal hemorrhage.

6. Patient is Rh Pos (weak D).

Possibility 1 + 2: Cannot be determined at this time.

Possibility 3 + 4: I'm assuming you've investigated these already.

Possibility 5: A KB Stain and/or Fetal Hemoglobin Assay could answer this question.

Possibility 6: The content of Anti-D reagents differ quite a bit, so we cannot expect the RBCs from some patients to elicit the same results if we change reagents. The 'Ortho vs Immucor' reagent difference has been expressed in here, but this goes for other manufacturers as well. Check out the information in the Quotient website about their various Anti-D reagents (beta, optimum, delta, etc.) as an illustration of the vast differences of detection capabilities. And this includes, as someone brought up in here, technique and timing. It all depends on what you want to see (DVI, for example) and how you want to see it. (Note that some Anti-D reagents do not require an AHG phase to detect 'weak D', some don't even require an incubation, some pick up DVI while others won't, etc.) So, in order for you to address this possibility, you need to find out what reagents were used and what is their capibility.

'nuff said?

Did I forget anything?

I have a situation here and need help.

We have an antenatal patient in first trimester. We did her blood group on 18.12.2012 and she typed as B Rh Positive. We used two anti-D with tube technique, one an IgM & other IgG+IgM blend (both monoclonal), and they showed 2+/3+ reaction. The reaction became more visible after the tubes were left at RT for some time. We also repeated the group in gel card (BIORAD, previously DIAMED) with DVI- anti-D and it was also positive 3+. Hence, we reported it as Rh Positive.

Today, her gynaec called & said that patient had a previous report as D Weak Positive. Her mother who is a doctor, got her typed again at another hospital and they have again given her report as B Rh D weak Positive. I asked the patient to be sent to us again for re-testing. We collected another sample and all the results were as previous- ditto.

Subsequently, I spoke to that hospital and they are using Johnson & Johnson (Ortho Diagnostics) cards (beads tech. - instead of Gel) as well as the same brand of IgG+IgM blend of anti-D which we are using. They got a weak reaction (under microscope) with the blend and around 2+ reaction on card with anti-D. For IAT the used IgG+C3d card had positive reaction and hence they have given it as D weak positive.

The patient is 21 year old primi in first trimester. I understand that if ever transfusion is required we should stick to Rh Negative, but how do we determine her real Rh status?

I have a situation here and need help.

We have an antenatal patient in first trimester. We did her blood group on 18.12.2012 and she typed as B Rh Positive. We used two anti-D with tube technique, one an IgM & other IgG+IgM blend (both monoclonal), and they showed 2+/3+ reaction. The reaction became more visible after the tubes were left at RT for some time. We also repeated the group in gel card (BIORAD, previously DIAMED) with DVI- anti-D and it was also positive 3+. Hence, we reported it as Rh Positive.

Today, her gynaec called & said that patient had a previous report as D Weak Positive. Her mother who is a doctor, got her typed again at another hospital and they have again given her report as B Rh D weak Positive. I asked the patient to be sent to us again for re-testing. We collected another sample and all the results were as previous- ditto.

Subsequently, I spoke to that hospital and they are using Johnson & Johnson (Ortho Diagnostics) cards (beads tech. - instead of Gel) as well as the same brand of IgG+IgM blend of anti-D which we are using. They got a weak reaction (under microscope) with the blend and around 2+ reaction on card with anti-D. For IAT the used IgG+C3d card had positive reaction and hence they have given it as D weak positive.

The patient is 21 year old primi in first trimester. I understand that if ever transfusion is required we should stick to Rh Negative, but how do we determine her real Rh status?

You could send one of her specimens to a immunohematology reference lab for molecular testing. They could tell you if she was a partial D or D variant.

I was going to suggest that myself, but often get told that it is too expensive in the USA.

Another (relatively inexpensive) possibility to try before resorting to molecular testing is to send her specimen somewhere for testing with the ALBAclone Advanced Partial RhD Typing Kit from Quotient. I've sent a couple of patients for this kind of testing and it was helpful in deciding what to do with them. I sent mine to our region's Red Cross reference lab. I don't know if all ARC reference labs have the kit, but I'm sure they are not the only ones using it. Quotient might be willing/able to help you find a reference facility that uses it.

Additional thought..........some reference labs have multiple anti-Ds from multiple manufacturers and may be able to get the same type of answers depending on the reagents they stock.

Edited January 28, 201312 yr by AMcCord
New Thought

Didn't know you had access to that. I would agree entirely AMcCord....much cheaper and usually gets an answer.

Didn't know you had access to that. I would agree entirely AMcCord....much cheaper and usually gets an answer.

Depends on the answer you are looking for. The 'ALBA' kit is very good in making the differance between an Rh variant and a weak D antigen (all 12 Monoclonal anti D's will be positive). If one or more monoclonals are negative you are dealing with a variant. The kit is not very good in naming the variant.

So I think it is a very good kit for hospitals to determine if you are dealing with a weak D or a variant D.

Peter

Thank you all for your prompt replies. We don't have any facility for sending samples to reference lab., but I spoke to BIORAD and they are going to do further work-up and let us know. Will keep you all posted with what their results are.