EGA Treatment for Weak D on Babies?

[Brenda K Hutson]

I received an e-mail from a former Medical Director, asking me a question for which I do not know the answer.   I have not used EGA in awhile (last couple of places used Generalists so we didn't get that technical).

His question had to do with using EGA on Cord Cells with a Positive DAT (mom O NEG; baby A NEG; Anti-A eluted) to go through to the Weak D phase (vs. resulting it as "unable to determine at this time" and giving Rhogam to be on the safe side).  I know when I worked there, we ran Positive and Negative Controls for the Antigens we treated (but we did not use EGA for this purpose).  I can't recall now if the Manufacturer's Inserts "recommends" both Positive and Negative Controls; or whether it is a "must?"

 

In asking a couple of technical experts, I received different replies:

 

1.  1 Reference Lab stated they don't use it for this purpose simply because they don't usually get cord work-ups; but they don't see why you couldn't.  They said they just use a Negative Control for any Antigen they are typing after EGA Treatment (said in their experience, they have seen problems with the Negative Control coming up Positive for some reason).  They "accept" the Manufacturer's statement as far as which Antigens have been proven to be destroyed by EGA.

2.  A 2nd Reference Lab said you could use EGA for this purpose but that you should run a Positive Control; and that Positive Control should be an Rh Positive Cell.

 

The Medical Director is questioning whether a known Weak D Positive Cell would be required to be tested as the Positive Control (which would be tough unless you had frozen Weak D Cells around). 

 

What are your thoughts....and do any of you use EGA for this purpose (and if yes, what controls do you run)?

 

Thanks,  

 

Brenda Hutson, CLS(ASCP)SBB

[Malcolm Needs ☆]

Sorry to be overwhelmingly stupid Brenda, but what is EGA? Is it another form of chloroquine diphosphate?

[Brenda K Hutson]

Sorry....EDTA Glycine Acid; and yes, it functions as chloroquine (and I think; at least in this country, is now more widely used than chloroquine).

Thanks,

 

Brenda

Sorry....EDTA Glycine Acid; and yes, it functions as chloroquine (and I think; at least in this country, is now more widely used than chloroquine).

Thanks,

 

Brenda

[Malcolm Needs ☆]

Thanks Brenda.

Bedtime now, but I'll try to reply tomorrow (now I know what EGA means!!!!!!!!!!!!!!!!!!!!!).

[galvania]

I can't speak for the States because you have different rules to Europe but I think that's overkill.  If you use monoclonal anti-D in gel, the reactions are so strong you are going to pick up most of your weak Ds anyway.  Granted not the very weak ones - but then you're not going to pick up a Del in an IAT either, so it's then a question of cut-off.  In Europe, I don't know of any lab (if someone knows otherwise, then I stand corrected) that would do anything other than test with 1, 2 or 3 anti-D clones (depending on local policy) one of which MAY detect DVI (again, depending on where you are), and if it's negative then that's it

[David Saikin]

I use a mld heat elution to remove the offending ABO/IgG ab  - it is usually pretty weak in gel to begin with (1-2+).  Sometimes that weak reactivity is not demonstrable in tubes.  Gel in the USA does not detect DVI.  We use a tube reagent anti-D which does find DVI in an IgG card (and Quotient has an I.S. anti-D which will detect DVI without ahg phase - I think).  .

[rravkin@aol.com]

Brenda, forgive me if I am being overly simplistic but if we were unable to determine the Weak D type then why not perform K/B stain on the mother's specimen and administer one plus (determine by K/B result) doses of RhoGam. And would there be any change in treatment of the baby if the bilirubin was elevated? We could try to obtain another specimen from the baby when the baby's rbc's are purely native; 3 to 6 months after birth I believe. These were just my thoughts.

[R1R2]

Brenda, forgive me if I am being overly simplistic but if we were unable to determine the Weak D type then why not perform K/B stain on the mother's specimen and administer one plus (determine by K/B result) doses of RhoGam. And would there be any change in treatment of the baby if the bilirubin was elevated? We could try to obtain another specimen from the baby when the baby's rbc's are purely native; 3 to 6 months after birth I believe. These were just my thoughts.

 

In my experience, most of these babies are truly Rh negative.   I think cost  and time are major reasons for resolution for positve DAT when weak D typing needs to be performed.   KB is expensive and time consuming.   Each vial of RHIG is >$400.   EGA treatment is less than $100 and takes just a few minutes.   I like the mild heat elution method too

[Dansket]

In my experience, most of these babies are truly Rh negative.   I think cost  and time are major reasons for resolution for positve DAT when weak D typing needs to be performed.   KB is expensive and time consuming.   Each vial of RHIG is >$400.   EGA treatment is less than $100 and takes just a few minutes.   I like the mild heat elution method too

When stating dollars, are you quoting hospital supply cost or patient charges?

[Brenda K Hutson]

I use a mld heat elution to remove the offending ABO/IgG ab  - it is usually pretty weak in gel to begin with (1-2+).  Sometimes that weak reactivity is not demonstrable in tubes.  Gel in the USA does not detect DVI.  We use a tube reagent anti-D which does find DVI in an IgG card (and Quotient has an I.S. anti-D which will detect DVI without ahg phase - I think).  .

I don't think that product is available from Quotient any longer?

Brenda

[Brenda K Hutson]

In my experience, most of these babies are truly Rh negative.   I think cost  and time are major reasons for resolution for positve DAT when weak D typing needs to be performed.   KB is expensive and time consuming.   Each vial of RHIG is >$400.   EGA treatment is less than $100 and takes just a few minutes.   I like the mild heat elution method too

I agree the EGA Treatment seems like the quickest method if you "really" want to distinguish Weak D from Rh Negative.  But even easier is to just administer Rhogam (be on the safe side).  I think this Medical Director was concerned because one of his staff had used EGA; but did not use appropriate controls (and I personally had never used EGA for this purpose so did not know what to say to him).  And what would be logical controls for this?  One Reference Lab told me they only use Negative Controls for EGA Testing (said they have actually seen Negative Controls come up Positive)...but I would want a Positive Control (since I don't use it where I currently am; can't recall if the use of controls is "recommended;" or "required").  Another Reference Lab said they would use an Rh Positive Cell as a Positive Control.  But this Medical Director was questioning this; thinking that "if" you are going to do this; should not the Positive Control be a Weak D Positive Cell?  I think his concern being that they called this baby an Rh Negative based on the EGA Typing (w/o proper controls) so did not give Rhogam.  I would be concerned about that also; but didn't have "absolute" answers to give him as far as the controls.

Thanks,

Brenda Hutson

[rravkin@aol.com]

I agree the EGA Treatment seems like the quickest method if you "really" want to distinguish Weak D from Rh Negative.  But even easier is to just administer Rhogam (be on the safe side).  I think this Medical Director was concerned because one of his staff had used EGA; but did not use appropriate controls (and I personally had never used EGA for this purpose so did not know what to say to him).  And what would be logical controls for this?  One Reference Lab told me they only use Negative Controls for EGA Testing (said they have actually seen Negative Controls come up Positive)...but I would want a Positive Control (since I don't use it where I currently am; can't recall if the use of controls is "recommended;" or "required").  Another Reference Lab said they would use an Rh Positive Cell as a Positive Control.  But this Medical Director was questioning this; thinking that "if" you are going to do this; should not the Positive Control be a Weak D Positive Cell?  I think his concern being that they called this baby an Rh Negative based on the EGA Typing (w/o proper controls) so did not give Rhogam.  I would be concerned about that also; but didn't have "absolute" answers to give him as far as the controls.

Thanks,

Brenda Hutson

So Brenda, as far as practice is concerned and in light of this information would it not be prudent and beneficial to give RhoGam when Weak D typing can not be performed do to the ABO incompatibility; and would there not be some benefit to ensuring that one dose of RhoGam is all that is needed for cases like this? If the mother does develop an Anti-D it may not be detected until her next pregnancy and this would not be good.

[Brenda K Hutson]

 To me, it would be easier to just give the Rhogam and say the Rh type is "unable to determine at this time." As far as the dose of Rhogam....you will still do the Fetal Screen (since you are saying the baby "may" be Weak D Positive).

Brenda

So Brenda, as far as practice is concerned and in light of this information would it not be prudent and beneficial to give RhoGam when Weak D typing can not be performed do to the ABO incompatibility; and would there not be some benefit to ensuring that one dose of RhoGam is all that is needed for cases like this? If the mother does develop an Anti-D it may not be detected until her next pregnancy and this would not be good.

 

[galvania]

Just as a matter of interest for all of those of you who go on to elute or treat with EGA or anything else - how many clinically significant weaka Ds (by which I mean, weak Ds or partial Ds that are known to be capable of eliciting an immune response) have you actually found by ddoing this in this type of situation? 

[R1R2]

I received an e-mail from a former Medical Director, asking me a question for which I do not know the answer.   I have not used EGA in awhile (last couple of places used Generalists so we didn't get that technical).

His question had to do with using EGA on Cord Cells with a Positive DAT (mom O NEG; baby A NEG; Anti-A eluted) to go through to the Weak D phase (vs. resulting it as "unable to determine at this time" and giving Rhogam to be on the safe side).  I know when I worked there, we ran Positive and Negative Controls for the Antigens we treated (but we did not use EGA for this purpose).  I can't recall now if the Manufacturer's Inserts "recommends" both Positive and Negative Controls; or whether it is a "must?"

 

In asking a couple of technical experts, I received different replies:

 

1.  1 Reference Lab stated they don't use it for this purpose simply because they don't usually get cord work-ups; but they don't see why you couldn't.  They said they just use a Negative Control for any Antigen they are typing after EGA Treatment (said in their experience, they have seen problems with the Negative Control coming up Positive for some reason).  They "accept" the Manufacturer's statement as far as which Antigens have been proven to be destroyed by EGA.

2.  A 2nd Reference Lab said you could use EGA for this purpose but that you should run a Positive Control; and that Positive Control should be an Rh Positive Cell.

 

The Medical Director is questioning whether a known Weak D Positive Cell would be required to be tested as the Positive Control (which would be tough unless you had frozen Weak D Cells around). 

 

What are your thoughts....and do any of you use EGA for this purpose (and if yes, what controls do you run)?

 

Thanks,  

 

Brenda Hutson, CLS(ASCP)SBB

I just reviewed the insert and controls are recommended, not required.    You will have to decide if you want to use a weak D cell as a positive control.  

[Brenda K Hutson]

 

Brenda, forgive me if I am being overly simplistic but if we were unable to determine the Weak D type then why not perform K/B stain on the mother's specimen and administer one plus (determine by K/B result) doses of RhoGam. And would there be any change in treatment of the baby if the bilirubin was elevated? We could try to obtain another specimen from the baby when the baby's rbc's are purely native; 3 to 6 months after birth I believe. These were just my thoughts.

I would perform a Fetal Screen vs. a KB. If the Fetal Screen is Negative....either the baby is Rh Negative (so doesn't really tell you whether their was a large bleed; but then this baby would not have needed the Rhogam anyway); or if the Baby is Weak D Positive, you would be looking for those Rosettes just as you would with an Rh POS baby. And of course if the Fetal Screen is Positive, then you would do the KB. Otherwise, the KB is a very time-consuming test. So I would just do the Fetal Screen and give the 1 vial if it is Negative....and if they really want to know (or it is your Policy to recommend this); then yes, you could ask that the baby be re-typed down the road.

Brenda

[AMcCord]

Except in the case of a weak D positive baby isn't a Kleihauer Betke recommended because the Fetal Screen won't reliably detect the weak D cells?

[Sandy L]

AMcCord is correct.  This is from the direction insert for Ortho, FetalScreenII

 

Limitations of the Procedure

If the infant’s red cells are shown to exhibit weak or partial RhD type, the test might not detect a feto-maternal bleed of more than 30 mL of whole blood.

 

We required a Kleihauer Betke Stain in lieu of Fetal Screen whenever the infant is Weak D.

[rebeccarjthomas]

I received an e-mail from a former Medical Director, asking me a question for which I do not know the answer.   I have not used EGA in awhile (last couple of places used Generalists so we didn't get that technical).

His question had to do with using EGA on Cord Cells with a Positive DAT (mom O NEG; baby A NEG; Anti-A eluted) to go through to the Weak D phase (vs. resulting it as "unable to determine at this time" and giving Rhogam to be on the safe side).  I know when I worked there, we ran Positive and Negative Controls for the Antigens we treated (but we did not use EGA for this purpose).  I can't recall now if the Manufacturer's Inserts "recommends" both Positive and Negative Controls; or whether it is a "must?"

 

In asking a couple of technical experts, I received different replies:

 

1.  1 Reference Lab stated they don't use it for this purpose simply because they don't usually get cord work-ups; but they don't see why you couldn't.  They said they just use a Negative Control for any Antigen they are typing after EGA Treatment (said in their experience, they have seen problems with the Negative Control coming up Positive for some reason).  They "accept" the Manufacturer's statement as far as which Antigens have been proven to be destroyed by EGA.

2.  A 2nd Reference Lab said you could use EGA for this purpose but that you should run a Positive Control; and that Positive Control should be an Rh Positive Cell.

 

The Medical Director is questioning whether a known Weak D Positive Cell would be required to be tested as the Positive Control (which would be tough unless you had frozen Weak D Cells around). 

 

What are your thoughts....and do any of you use EGA for this purpose (and if yes, what controls do you run)?

 

Thanks,  

 

Brenda Hutson, CLS(ASCP)SBB

WHen using EGA treated cells for Weak D testing, we run a Weak D positive cell as a control.  This is a cell that you can purchase.  RJT

[galvania]

OK - I'm going to be controversial.  The baby is RhD negative using several reliable anti-D reagents that are known to pick up all but the weakest Weak D antigens, and the baby has a positive DAT.  Why are you even considering giving RhoGam?  The baby is RhDnegative.  No need to do a Kleihauer (unless the Doc wants to check for fetal bleed, but nothing to do with the Rh group) So the financial equation is not between how much does RhoGam cost compared to EGA (and what about the technician's time) or Kleihauer but the cost of RhoGam and/or EGA and/or Kleihauer against having a good system in the first place.  And are you going to do an adsorption/elution on each one as well just to make sure it's not a Del?  Why not a genotype?  It would be more accurate? (Although soon, that probably WILL be the case in Europe - pre-natally - using fetal DNA extracted from maternal plasma.  Some countries already doing that)

[epfeiffer]

I know I'm a little late responding to this thread, but I didn't see the answer I would've provided, so I thought it worth mentioning.  When we would EGA treat a neonate red cell to rule out weak D we would run a drop of EGA treated red cell with an in house 6% albumin as our negative control.  The control served the purpose of verifying positive reactions were truly due to the presence of the antigen and not the result of an incompletely removed maternal IgG.  We did do an extensive validation prior to using the EGA kit however, verifying which antigens were denatured, so we had complete confidence the D antigen was left intact. (Immucor was correct by the way, and the validation was completely unnecessary.)