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Eluates on babies with positive DATs


Mindy
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We do all DATs in gel.  We do baby DATs by washing the cells, spinning to concentrate, taking 10 ul in 1 ml of MTS buffer, adding 50 ul to an MTS IgG card and spinning.  We do complement DAT by the same method, using a buffered gel card, 50 ul of 0.8% washed cells.  We always run a positive and negative control, since we want to make sure we have added the 25 ul of anti-C3b, C3d to the card.  Otherwise everything will be negative!

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15 minutes ago, mollyredone said:

We do complement DAT by the same method, using a buffered gel card, 50 ul of 0.8% washed cells.  We always run a positive and negative control, since we want to make sure we have added the 25 ul of anti-C3b, C3d to the card.  Otherwise everything will be negative!

Would it not be substantially cheaper to perform this in tubes, rather than gel cassettes?  It is not as if a positive DAT in a baby sample is going to be exactly a common occurrence.  I mean, I have seen maybe two, three in my professional life (43 odd years - coming up to 44), and both involved maternal Kidd antibodies.  CAT cassettes are just so expensive!

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  • 2 weeks later...
On 5/25/2013 at 6:58 PM, Dansket said:

For those who routinely do eluates, what evidence/data have you to support such a policy?  Whether an eluate is positive or negative, when have eluate results changed the physician's decision to do or not to do?

THis is an excellent comment.  As long as the mother is not sensitized to the K ag I cannot see a reason to perform an elution.  With an IgG+ DAT I would expect the baby to be monitored and treated appropriately whether the DAT is due to ABO or other specificities.  I have also encountered a DAT+ cord blood due to a private ag from the father . . .  never able to id the causative antibody (even NYBC could not).   All serologies were negative except the DAT.   The baby was treated the same - observed and treatment given accordingly.

Edited by David Saikin
clarification
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1 hour ago, David Saikin said:

THis is an excellent comment.  As long as the mother is not sensitized to the K ag I cannot see a reason to perform an elution.  With an IgG+ DAT I would expect the baby to be monitored and treated appropriately whether the DAT is due to ABO or other specificities.  I have also encountered a DAT+ cord blood due to a private ag from the father . . .  never able to id the causative antibody (even NYBC could not).   All serologies were negative except the DAT.   The baby was treated the same - observed and treatment given accordingly.

I agree David.  THIS baby would not be treated any differently.  However, the next baby, or, more accurately, the next foetus, and CERTAINLY, the next pregnancy may well be treated differently, and that, if you don't mind my saying so, is the whole point.

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  • 3 weeks later...
On ‎11‎/‎25‎/‎2017 at 8:26 AM, EAB81 said:

Since we're on the topic of DATs performed on cord bloods, does anyone have a procedure I might look at for doing the DAT in gel? The previous BB Super had begun the task of researching but didn't get far. Thought maybe I'd pick up the torch.

Ortho provides a template DAT procedure for gel you might want to look at.  We now do our cord DATs in gel, on the Vision mostly.  We have long done only IgG DATs on cord blood so use the IgG cards for this.

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At our facility, We used to do Eluates on Positve DATs for the CBs until last year. Our policy was revised and now we only do eluates if physician requests us as a part of differential diagnosis when they have ruled out all causes of hyperbilirubinia and anemia. We call the floor and inform them about the positive DAT results. 

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  • 1 month later...

What would you do for this scenario ?

 

Mom : A negative with a negative antibody Screen.  She received RHIG at 28 Weeks and has history of an Anti-C

Baby: O positive with Positive DAT

 

Our techs logic was that it couldn't be the RHIG or the Anti-C causing the DAT because the screen is negative.    

 

 

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1 hour ago, amym1586 said:

What would you do for this scenario ?

 

Mom : A negative with a negative antibody Screen.  She received RHIG at 28 Weeks and has history of an Anti-C

Baby: O positive with Positive DAT

 

Our techs logic was that it couldn't be the RHIG or the Anti-C causing the DAT because the screen is negative.    

 

 

Well, the first thing to say is that it could be, in particular, a result of the RHIG, as nobody, not even the producers, know what specificities are in there.

The other thing to say is, that they may be right (but for the wrong reasons - see the sentence above!).  It could be that the baby has inherited a gene from Dad, that means the baby is expressing a low prevalence antigen on his/her red cells that is not represented on either your screening red cells, or your antibody identification red cells, which would explain why the eluate is negative with these cells - assuming that this test has been done (reading your post again, this is unclear).  IF what I say is correct, then, without doubt, the eluate should be tested against the Dad;s red cells (if the Mum is really group A, and the baby group O, there should be no problems with ABO incompatibility).

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3 hours ago, amym1586 said:

What would you do for this scenario ?

 

Mom : A negative with a negative antibody Screen.  She received RHIG at 28 Weeks and has history of an Anti-C

Baby: O positive with Positive DAT

 

Our techs logic was that it couldn't be the RHIG or the Anti-C causing the DAT because the screen is negative.    

 

 

My question is when was the most current antibody screen performed, just prior to the RhIG injection or just prior to the delivery, or after the delivery?  Also, as I think about it, was an elution performed at the time of the positive DAT? 

One more thought, if the antibody screen was performed just prior to or just after delivery most of the available antibody could be attached to the babies cells resulting in a negative antibody screen. 

Edited by John C. Staley
additional thoughts came to me.
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