For pre transfusion compatibility testing , What is the importance of positive DAT on a neonatal sample whose ABS(3 cell panel) is negative whereas all neonatal transfusion are O red cells.

For pre transfusion compatibility testing , What is the importance of positive DAT on a neonatal sample whose ABS(3 cell panel) is negative whereas all neonatal transfusion are O red cells.

You will be doing an antibody screen on the mother's serum in a neonate and the DAT is testing for maternal activity against the baby's red cells - HDN or at least sensitisation. The DAT has less to do with transfusion and more the HDN status of the neonate.

Agreed.

The positive DAT could be caused by subclinical levels of maternal IgG ABO antibodies, a maternal antibody directed against a low incidence antigen passed on to the baby via the paternal genes, or could be completely coincidental, but should not interfere with transfusion as long as, as Auntie-D says, the units are compatible with mum's plasma/serum.

Thanks Auntie and Malcolm

Some times we do not have mother's sample so we just use neonate's sample. Units compatible-with baby sample by AHG. Yesterday I had a similar case, so posted it here.

Thanks Auntie and Malcolm

Some times we do not have mother's sample so we just use neonate's sample. Units compatible-with baby sample by AHG. Yesterday I had a similar case, so posted it here.

We would not crossmatch a baby without a maternal sample - it is deemed a minimum requirement to antibody screen the mother and crossmatch against the maternal plasma. This is the case for neonates until 4 months (though above about 8 weeks we crossmatch against both).

As well as allowing a better idea of what antibodies the mother has, it also means that huge amounts of blood don't have to be drawn from a teeny baby - just a spit to do the group...

Thanks-D,

If the situation really doesn't make sense - like Malcolm says - check an eluate from the DAT against a antibody screen trio and A cells and B cells and if you get no reactions, check the eluate against Dad's cells, if you can get them. You might also crossmatch for the infant with the eluate, some hopsitals do that too. If you can get Dad in, you might then be able to get Mom too and check her serum against Dad's cells too.