Well, this is one I haven't seen before.....

We were asked to perform a Cord Blood Type on a newborn who was being transported to another Hospital.  The Mom is A POS; the Baby is A....but the Rh is now undetermined.  It shakes off rough and you can see some heavier red dots.  When you look microscopically, there are a lot of agglutinates.  However, the Control is Negative; Weak D Testing showed only minimal clumps microscopically; the DAT is Negative.

 

We recommended to the receiving Hospital that they perform a heelstick.  I can only think the Baby is Rh NEG and has some of the mother's cells mixed in the Cord Specimen; but the Weak D does not make sense compared to the Immediate Spin.

 

Thoughts??  

 

Thanks,

Brenda Hutson, CLS(ASCP)SBB

you may want to see if you can detect mixed field in other typings such as C, E, c  to add to the idea of possible contamination with mom;s blood.

you may want to see if you can detect mixed field in other typings such as C, E, c  to add to the idea of possible contamination with mom;s blood.

 

Or do a Kleihauer-Betke, sort of read in reverse.

I have a few pts that Rh type like this - 3 of whom are employees here.  Very weak testing with anti-D in gel.  In tube, your description fits my pts to a tee.  Very weak agglutinates at immediate spin with no change at weak D (ahg).  I had a Quotient anti-D typing panel at the time and they all had the same reactivity.  2 were OB patients and I told their MD we were going to treat them as Rh negative (RhIg candidates).  One had a red cross card stating she was Rh+.  I told her she was, as far as being a donor goes.  Interesting stuff.  It's probably too late for a heel stick . . .

I suppose it could be Rh mosaicism.  It is a lot more common than a lot of people think.

 

The really rank outsider as an explanation is chimerism, where one foetus has been totally adsorbed into the other (which could also give this kind of reaction with antisera of other specificities).  The interesting thing about this is that the majority of red cells (those typing as D Negative could actually be from the adsorbed twin, and the minority from the living twin - it is not always as one might expect, that the living twins blood group would dominate.  This explanation is, as I said, a rank outsider.

On second thought, if administration of  RHIG is not an issue (mom is Rh pos correct?), why not call the baby Rh neg? 

That's what we would do, since any later typings of the baby might look negative, and we don't look at the tubes microscopically or do a Du on adults.

Personally, Brenda, my first suspicion would be your initial explanation.  I think that you might see the pattern that you have described if the baby was Rh Negative and had just a very minor contamination with Mom's Rh Positive blood.  (I could see that the Weak D might be very weak if there is only a very minor population of the Mom's Rh Pos red cells,)  I have seen this scenario.

 

 

Donna

I agree with your assessment Brenda.  And the fact that it is a cord blood makes me think maternal contamination.

 

Having done ped blood banking using heel stick we would get a "true type" on the baby.  Then either give O pos or neg pedi units and if nay doubt at all on Rh type it would be O neg.

It could of course be Wharton's Jelly

Thanks everyone for your suggestions/thoughts.  Baby is no longer here (was transferred) so cannot do healstick.  Cells were washed (many times) prior to testing; so do not suspect Wharton's Jelly.

Interesting that one of you mentiioned Quotient in that we use that Manufacturer for our tube testing Antisera (and it changed recently....hmmmm).  I think I will order a bottle of Anti-D from a different Manufacturer because we "just" got another baby that typed like this.

We reported it out as "unable to determine."  Had the baby stayed here, we would have given O Negative RBCs anyway.

Thanks again!

Brenda

Addendum:  Heelstick sample on this 2nd problem cord specimen, was clear-cut Negative.  So wondering about tubes cord blood is being placed in?  Maybe different lot#??  More investigation to do....

Brenda

Quotient has reported a tendency for their anti-D blend to detect i on cord cells very weakly.  They told me that it is not that the reagent is contaminated with anti-i but that the monoclonal that they use tends to cross-react with the i antigen on baby cells. We had one that looked like this at IS but was negative at AHG and they said to call it negative. Call their technical support and they will be very helpful.

^{Thanks a lot Mabel....we just got another one.  I purchased another Manufacturer's Anti-D and it was Negative at I.S. and AHG; but Quotient is coming up 1+ at I.S. but Negative at AHG.  I will call as you recommend; had not heard that.}

^Brenda

Some quotient anti-Ds are only IgM so they won't react with anti-IgG.  I think the blend is the only one that has IgG antibody in it.  I played with all 3 varieties a few years ago.

Addendum:  Heelstick sample on this 2nd problem cord specimen, was clear-cut Negative.  So wondering about tubes cord blood is being placed in?  Maybe different lot#??  More investigation to do....

Brenda

I might also question the initial collection technique for the cord bloods.  You might want to ask the L/D nurses what their process is for collecting and labeling.

Some quotient anti-Ds are only IgM so they won't react with anti-IgG.  I think the blend is the only one that has IgG antibody in it.  I played with all 3 varieties a few years ago.

We just recently switched to the blend....did not have this problem before then.

Brenda