Jump to content

D Pos then D Neg


Recommended Posts

Work at a reference lab, use the provue. We had two separate maternity patients D pos, then 6 months later they are D neg. The doctors are mad since now the rhogam was not given. One was found because the mom was pregnant again. We dont have access to any other history for these patients.

Thanks!!!

Link to comment
Share on other sites

There are a number of possibilities:

1. Specimen collection/labelling error

2. Pipetting or other technical error

3. Different technique/method being used for the two tests

4. Different reagents (2 different clones, or once human, once clone) being used on the two occasions

5. Contamination in the first test, causing false positives

6. Contamination in the second test causing false negatives

Possibly others......

Link to comment
Share on other sites

There are a number of possibilities:

1. Specimen collection/labelling error

2. Pipetting or other technical error

3. Different technique/method being used for the two tests

4. Different reagents (2 different clones, or once human, once clone) being used on the two occasions

5. Contamination in the first test, causing false positives

6. Contamination in the second test causing false negatives

Possibly others......

If it wasn't a mix-up in patient's/tubes, then I would bet it's the different reagents. I deal with this same issue every single week, having to explain to the doctor's why we get Rh Negtatives and the mom delivers and is typed at the hospital as Rh Positive. We use Immucor series 4 and 5, but one of the main hospitals uses the Gamma Clone. Drastic difference it the reagents.

Link to comment
Share on other sites

We had this problem too. When I investigated, i found that Ortho uses a mixture of clones for the ABO Gel cards versus their Anti-D typing reagent. We would get a positive on provue and neg when we did the retype using tube method. We then switched to Immucor Anti-D for Rh typing on bench and it matched the provue results. Ortho KNOWS that there is a problem with their typing sera but won't admit it.

When we have a discrepancy between Rh types, we have done a weak D test on new negatives that were previous positives and they always reacted at AHG.

Either the patient has less D antigens on cells or change in strength of testing reagents. Tell the doctors that the ONLY pateint that will develop Anti-D is the partial D patient, which is rare. Weak D patients won't develop Anti-D

Link to comment
Share on other sites

If it wasn't a mix-up in patient's/tubes, then I would bet it's the different reagents. I deal with this same issue every single week, having to explain to the doctor's why we get Rh Negtatives and the mom delivers and is typed at the hospital as Rh Positive. We use Immucor series 4 and 5, but one of the main hospitals uses the Gamma Clone. Drastic difference it the reagents.

We (NHSBT in the UK) have had a spate of RhD Negative pregnant ladies "turning" weakly RhD Positive towards the end of the pregnancy, and this is using exactly the same technology and reagents throughout the pregnancy. We are going to be doing a proactive study on such cases, and look at there RHD gene.

I will let you know the outcome, eventually, but they are rare cases, and so the study could take some time to come to fruition.

:confused::confused::confused:

Link to comment
Share on other sites

We have a lung cancer patient who was typed twice in 2008 as O Negative by two different techs. When she came in two months later she typed very weakly O Positive by two different techs. We decided to transfuse her with O Negative again, since that was her history. Since that time, her anti-D reactions have gradually increased in strength to where she is reacting 4+ with the antisera. Nothing has changed during this time--reagents, manufacturers, procedures--nothing. The doctors office says she is not on any "strange" drugs that would cause this. I have heard of antigens weakening with age/treatment, but can anyone come up with an explanation for this? We finally changed her blood type and are now transfusing O Positive red cells with no negative consequences.

Link to comment
Share on other sites

There is a theory going around that it may be a clone of red cells that are D Positive that would normally be supressed, but that in certain disease states, this clone can grow and take over the D Negative clones.

This theory has been put forward by some extremely emminent workers in the field (although I will not name them here, until more work has been done to prove/disprove their theory).

Link to comment
Share on other sites

Interesting!! Please bring this topic up again here on BloodBankTalk when you have more information that you can share.

Not quite the same topic, but we are taught that some leukemias and malignancies can cause a temporary weakening of the antigens of the ABO System, in particular the A antigen. I observed several examples of this phenomenon early in my career, but have not seen such a case for many, many years. (I'm not talking about any change involving/caused by a transplant.)

Have some of you observed this pattern? (ie: Observed in the past, but rarely today.) Does anyone know how/why this phenomenon happens? (And why it happens less today?) (Stronger reagents?) (Different treatment/chemotherapy regiments?)

Link to comment
Share on other sites

Interesting!! Please bring this topic up again here on BloodBankTalk when you have more information that you can share.

Not quite the same topic, but we are taught that some leukemias and malignancies can cause a temporary weakening of the antigens of the ABO System, in particular the A antigen. I observed several examples of this phenomenon early in my career, but have not seen such a case for many, many years. (I'm not talking about any change involving/caused by a transplant.)

Have some of you observed this pattern? (ie: Observed in the past, but rarely today.) Does anyone know how/why this phenomenon happens? (And why it happens less today?) (Stronger reagents?) (Different treatment/chemotherapy regiments?)

Will do.

We do see the weakening of the A antigen on a fairly regular basis still.

There was one Consultant Haematologist at a London Teaching Hospital who, unfortunately, had AML himself. The Laboratory could tell whether he was in remission or in relapse by the strength of the A antigen on his red cells.

:eek:

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
  • Advertisement

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.