Weak D

[momie]

the thing i am wondered aboout......since if a lab is not performing a weak D on adults the if a case comes up like while doing the ABO and D typing, it gives a weak reaction in tube for the D -antigen....so what should the protocol be for those hospitals who dont do weak D testing on adults............does they always give RH-neg blood to those who are Rh-positive?????

[David Saikin]

They should . . . there are a variety of scenarios which result in weak D+. Some of these may result in the patient becoming sensitized to the D ag. It is more prudent to consider these folks as Rh= for transfusion purposes. Donors who test weak D+ are called Rh+.

[Kathy]

What about patients who get autologous units? They would be Rh negative in the blood bank system, but their unit would be labeled Rh positive.

[David Saikin]

You are absolutely correct . . . You ned to have a policy which addresses this . . .

[Kathy]

You are absolutely correct . . . You ned to have a policy which addresses this . . .

I am new to this "supervisor" thing. Do you have any suggestions for what my policy should be? Maybe require the patient to be transfused with only Rh negative units except for the Rh positive autologous units? I don't even know if my computer system will allow the patient and autologous unit's Rh types to not match.

[BBK710]

I am new to this "supervisor" thing. Do you have any suggestions for what my policy should be? Maybe require the patient to be transfused with only Rh negative units except for the Rh positive autologous units? I don't even know if my computer system will allow the patient and autologous unit's Rh types to not match.

When we receive an autologous unit labeled Rh positive for a patient who types or has a previous Rh negative we will do weak D testing. If the patient tests weak D positive we report the patient as Rh positive with a comment that it is a weak D and patient should be transfused with Rh neg blood after the autologous unit has been transfused.

[adiescast]

We also do the weak D test if an autologous unit comes in labelled Rh positive. When we report it, we report the patient as Rh negative, weak D positive. The computer will still give a QA failure for it and we answer the QA failure with the weak D info. That way the patient's permanent type is still Rh negative for future transfusions.

[Malcolm Needs ☆]

I know (and understand) what you mean Julie, but just playing the Devil for the moment, where do you get your "anti-weak D"?

[YorkshireExile]

Malcolm,

From Diamed, we use "ID-Anti-D for confirmation of D variants by IAT" - to quote the manufacturers instruction title. To further quote - "This can be performed using a monoclonal anti-D formulated to detect weak D`s and DVI on the ID-card coombs anti-IgG." We use this reagent for confirmation when our cord blood groups are Rh negative.

Is this equivalent to "anti-weak D", or are Diamed using marketing terminology falsely!

[Malcolm Needs ☆]

Well, yes. What you are using are anti-D reagents that are picking up specific epitopes, or a mixture of epitopes, but they are still anti-D reagents - not anti-weak-D reagents.

In other words, these reagents will also detect the "normal" D antigen.

As far as I am aware, there are no reagents that detect weak D that do not also detect "normal" D.

[adiescast]

I know (and understand) what you mean Julie, but just playing the Devil for the moment, where do you get your "anti-weak D"?

Haha Malcolm! We get our "anti-weak D" from Tradition. Where do you get yours?

Seriously, its gotten to the point where you bend over backward to get the computer to do what you need it to do. There are times when I wish for the days when blood banking was as much art as science and you could just use common sense to decide what to do. On the other hand, we were doing alot more testing then that is no longer considered to be necessary, so maybe it's not so bad.

[Malcolm Needs ☆]

True, true!!!!!!!!!!!!!!!!!!!!!!!!!!!

[mla]

Just to add a little to this discussion. We don't normally test for weak D on adults, unless they have an Rh positive autologous unit. We recently had a patient with an autologous unit who tested weak D positive. The zinger was that he also had anti-D. (Last transfusion was 20-30 years prior.)

[AMcCord]

Just to add a little to this discussion. We don't normally test for weak D on adults, unless they have an Rh positive autologous unit. We recently had a patient with an autologous unit who tested weak D positive. The zinger was that he also had anti-D. (Last transfusion was 20-30 years prior.)

Cool! Bet explaining that to the nurses was fun.