Hello,

Does anyone use the Biotest "D" reagent and if so, have you had any problems with false negative reactions??

We have had a problem with very weak reactions however, I don't think there have been any false negatives.

With Immucor, techs were used to a 4+ the vast majority of the time. With Biotest, you can expect a 3+ frequently. Sometimes, (much more frequently than with Immucor) you get a +/- or a 1+. Techs who are expecting a 4+ will shake too hard and too long and they can shake away a +/- or a 1+ until it looks negative. This has happened several times with us. For adults, it is a tollerable error (no IAT is done on adult patients). For newborns and cord bloods, we have always required IAT on negatives (weak D testing), even with Immucor. What we find with Biotest is that if it is weak at IS, it doesn't really get stronger at IAT, but it doesn't go away either. Our rule for Biotest is: if it is positive in any way at any phase, the person is to be considered Rh positive.

Aren't you concerned that you might be sensitizing some D mosaic patients?

Sorry David, but do you actually mean D mosaic, or do you mean partial D? The two are not synoymous.

I guess I mean partial D (only a part of the mosaic) . . .

Sorry David, but do you actually mean D mosaic, or do you mean partial D? The two are not synoymous.

I assumed he meant DVI - being called Rh+, getting Rh+ blood, and then forming anti-D.

I assumed he meant DVI - being called Rh+, getting Rh+ blood, and then forming anti-D.

Oh that it were as simple as that! Partial DVI is only one of very many (about 70) partial D types that can produce an alloanti-D; it is just that partial DVI is the "most famous".

:cries::cries:

Hello,

Does anyone use the Biotest "D" reagent and if so, have you had any problems with false negative reactions??

Yes, We do have problem with this reagent with false negative, and we have already informed our supplier.

We also were having problems. Switched back to Ortho anti-D.

We also see too many "weaker than expected" reactions with this reagent. We are switching back.

We have strong reactions. But it is only used for retyping donor units.

But many of those partial D's that can make anti-D will react 4+ with anti-D typing sera of various sorts. Not all patients that type weakly with the anti-D are partial D either, right? Wouldn't it be nice if we had a reagent that would always react differently with those capable of making anti-D?!

Isn't VI one of the more common ones that can make anti-D that has a monoclonal antibody that can detect it at IS? That reagent is good for donors and babies at least. I'd rather not use it on my other patients.

These variations in reactivity make it tricky to compare the anti-D antisera on the market. There is some good data on how they all react but it is hard to find all in one place. Maybe someone could put that together for this site. Might even be a good SBB student project. Of course, the Bio-test (now Bio-Rad) and Alba (now Quotient) reagents bring a whole new mix to the equation.

So in the rare case that the patient, as long as there is no potential for child bearing, makes anti-D. So what. The worse case scenario involves transfusion of Rh pos red cells in an emergency. This could cause an extravascular reaction, meaning decreased red cell survival.

We used this reagent and much to our dismay we found that when some of the the patients we called Rh neg went to the hospital to deliver they were typed as Rh positive 4+ in tube and in gel. We had the hospital send us the samples and they were repeatedly negative with Biotest anti-D blend on immediate spin. They all came up as weak D positive with Biotest but we do not do weak D testing. Consequently, we changed to Quotient Anti-D alpha and we have not had anymore discrepancies. We had so many upset patients and physicians thinking we had mis-typed the samples that our credibility came under suspicion until I could explain it to the docs (don't think they understood anyway).

Thanks for the input. As it stands now we have to confirm all negatives with Ortho...