We recently had a baby born to woman with an allo anti little c. We believe the baby is Rh negative but weak D status has not been confirmed due to a positive DAT (2+). The Rh control tube and the weak D tube were equal in strength to the DAT. The cord cells were typed as litle c positive. If the baby is confirmed to have passive anti c by antibody screening and required a red cell transfusion, would it be acceptable to transfuse Rh positive RBCs that lack the little c antigen because formation of an allo anti D is unlikely? Is anyone aware of plasma exchange being used as a method for removal of maternal antibody in a neonate? Thanks for any thoughts you may have.

 

Terry

It would be unlikely that the infant is D-negative.  If the mother has an anti-c, she is most likely an R1R1 so would be contributing an Rh-pos gene to the infant.  I realize the mother could be an R1r' so it is possible the infant could be D-negative.  With that said, a plasma exchange is generally an automated procedure so is not really feasible on a neonate.  The bulk of any passive antibody is attached to the RBC so it's more important to remove the sensitized RBCs which will be the source of the bilirubin.  It would also be very difficult to obtain a Red Cell unit that is D-negative and c-negative.  So has you mentioned, you could use D-positive, c-negative whole blood for the exchange or use D-negative, c-positive units and anticipate performing multiple exchanges if necessary.  Whether the infant is a male or female may also influence your decision.  

We don't have a full Rh phenotype on the maternal sample but she is Rh positive and E, c negative.  The baby is male.

You should have no trouble at all phenotyping the baby if you use monoclonal IgM  reagents.  You should also have, as a matter of course, the mother's phenotype.  These two pieces of information are not  an optional extra.  AND you should see what you're getting out of the eluate.

I had a mom once with anti-c and I remember planning what I could do if the baby were Rh neg.  It turned out to be!  Fortunately, no transfusion was required for the baby.  I agree with SMW above.  I would have a hard time giving D pos to a baby girl, but if someone could convince me that was better than c+ in the presence of anti-c, I would go that way.

We are doing titers on a prenatal patient with anti-c and anti-Fyb.  Lots of fun!

Wouldn't worry about the anti-Fyb - but, of course, there is always the exception to the rule!!!!!!!!!!!!!!!!!