I have been scratching my head:confused: trying to come out with an explanation of this strange serological finding of a neonate sample. This baby girl was born two days ago and mum has anti-G. ABO/Rh and DAT were requested to be performed on the baby's sample. Baby girl's blood type was group O which is compatible with mum ( mum is group O negative). The D typing of the baby was negative at IS and the weak D test was negative. The DAT performed later was found to be 3+ with anti-IgG. Baby's Rh phenotype: C+,c+,e+,E-. My question is why weak D testing was negative where cells have positive DAT? Wondering if anyone has encountered such testing scenarios or perharps a good explanation to this finding. Thanks

Emergency room

Did the results come out the same when repeated?

That would be my question too. Having said that, the anti-D reagents used in the UK for testing cord blood are direct agglutinins, and so a positive DAT would make no difference.

Are you certain the the anti-D you use detects DVI? It probably does but may not . . . check the pkg insert. It still should have been positive with a positive DAT, esp one so strong.

Are you certain the the anti-D you use detects DVI? It probably does but may not . . . check the pkg insert. It still should have been positive with a positive DAT, esp one so strong.

Sorry for being thick David, but was your question addressed to emergency room or to me? If it was to me, the answer is "yes", they do detect Partial DVI.

Sorry for being thick David, but was your question addressed to emergency room or to me? If it was to me, the answer is "yes", they do detect Partial DVI.

To emergency room - YOU, sir, are not thick.

I've seen weak pos DATs elute off during the incubation for weak D testing, but never a strong one like that. And blocking of the D sites with maternal anti-D (or G) wouldn't explain it because the cells are coated with antibody so should react at AHG regardless of their antigen type. Hmmm. Either the IgG detected by the DAT is not "real" or the testing elutes antibody off or the weak D test is falsely negative for some reason. Did you use the same AHG reagent for both tests?

Sorry everyone for the late reply. I went back and reviewed the workup again and yes the DAT was repeated in tube and it was still positive (1+s). The initially DAT performed was done on gel. Because we were concerned about the so-called "blocking" effect, we also EGA treat the cells and used the treated cells to performed weak D testing.

Emergency room

If I remember correctly, Anti-G demonstrates like an Anti-D and an Anti-C. Could moms

Anti-G be reacting against babys C+ cells???

Just a thought.

If I remember correctly, Anti-G demonstrates like an Anti-D and an Anti-C. Could moms

Anti-G be reacting against babys C+ cells???

Just a thought.

Right- the baby could be D neg, C pos and the mom's anti- G is reacting against the G antigen on the C pos cells.