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Hello, at our facility, we send any positive DAT(we use polyspecific) on cord blood to reference lab for work up/elution for HDN. my question is, what should be done with mother/ should a new type and screen be performed soon after cord blood collected? our procedure says if moms antibody screen is positive, start HDN workup. so should it be a recent antibody screen? or prev prenatal antibody screen result? confusion regarding mother, if antibody screen negative don't send? could an antibody eluted off be missed if moms antibody screen was negative?

I am not original author of procedure, originally placed into service in 2006, biannually reviewed. and I am a recent hire, non blood banker, generalist.

any clarification would be greatly appreciated or an actual  cord blood, HDN workup, or positive dat procedure would be great!

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Posted (edited)

The highest percentage of DAT Positive Cord Bloods are as a result of sub-clinical ABO HDFN (say, a group A mother and a group B baby).

The next highest in terms of percentage is now D Positive babies of mothers who have been given anti-D immunoglobulin during the pregnancy (most certainly in the UK).  Although the DAT is often positive, it is always a sub-clinical condition.

Probably the next in line in terms of positive DAT is idiopathic positive DAT in the baby, probably due to non-specific uptake of proteins on to the red cell membrane.

Unless the mother has a known atypical alloantibody in her circulation, it is highly unlikely that a positive DAT will result in clinically=significant HDFN (unless the father has passed on a gene to the baby, resulting in the baby expressing a low prevalence antigen on its red cells, and the mother having the cognate antibody in her circulation - but this is REALLY rare).

In most cases, do nothing, unless you have time and money to waste.  Wait until the paediatrician/obstetrician decides there are clinical reasons to start worrying, rather than just a positive DAT.  The baby needs to be treated, NOT the test result.

Edited by Malcolm Needs

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For Mom, we routinely perform Type & Screens on all OB patients.  For Baby, we routinely perform cord blood testing (ABO/Rh & IgG DAT) from deliveries of all Rh Negative and Group O moms. 

We still perform additional testing when the baby has a positive DAT (IgG testing only).  When there is an ABO incompatibility or mom has a current detectable Anti-D due to Rh Immune Globulin, are any facilities still doing more testing on the cord blood?  We still do even though the baby is going to be treated the same way.  Our protocol is use of a bili light and for a bilirubin to be performed 12 hours after delivery. 

I haven't reviewed recent literature on the subject.  Curious to see what other facilities are doing for positive DATs when the is not a clinically significant antibody involved. 

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We do an eluate only if the Dr orders one, and we haven't had that in years.   We only do the cord bloods of O and all Rh neg moms anyway.  An O mom with a B baby can frequently be seen to have  a more aggressive HDN - but usually treated just with Bili lights and hydration, occasionally they also don't let the mom breastfeed.

Any ABO HDN eluate workup really doesn't yield anymore useful information than you already know - Mom's are usually O and the babys are A or B  - DAT mystery solved.

On the rare clinically significant antibody - try to find whatever it is mom has and phenotype the baby (if possible) if the DAT is positive -  might be worth sending out if you can't do any of that.  Do you have to send out AB Titers if they are monitoring the pregnancies?  Do you usually know in advance, the moms with positive antibody screens or do you get little prenatal work? That might effect what you need to do.

On the very rare(!): Dad has a rare antigen and mom has the corresponding antibody -  good luck even remembering that if shows up.  The only real way to work one of those up is to have specimens for Mom and Dad and crossmatch Mom with Dad's cells.  If Mom had a negative antibody screen (frequently) but is incompatible with Dad and the baby - send that out for information to use on the next pregnancy - if there will be one.  Otherwise - the current infant will have to be dealt with as well as possible - Bili lights, hydration, maybe exchange transfusion with units compatible with Mom's specimen.  

That is what we would do.

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46 minutes ago, cswickard said:

If Mom had a negative antibody screen (frequently) but is incompatible with Dad and the baby - send that out for information to use on the next pregnancy - if there will be one.  Otherwise - the current infant will have to be dealt with as well as possible - Bili lights, hydration, maybe exchange transfusion with units compatible with Mom's specimen. 

But Dad and baby could both be incompatible with mum major side.  E.g.  Mum could be group A and Dad and baby group B, or have I read this wrong (it wouldn't be the first time)?

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We stopped performing Eluates on cord blood years ago.  We initially said only if mom had a positive antibody screen, and then went to if Dr. orders.  They never do, even when mom has a known antibody and the baby is severely affected.  They know the source of the problem and treat the baby accordingly.

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I haven't done an eluate on a cord blood in many years.  If mom has a clinically significant alloantibody, we antigen type. If we can explain the positive DAT with mom's antibody, her blood type (O), or her current dose of RhIG, we won't consider a routine elution. If the baby's bili is unexpectedly high or if we have some other reason to suspect that an alloantibody is causing a problem, we would perform an elution.

Our cord blood panels are ABO/Rh and a DAT. If mom is type O and baby is type A or B, we perform an immune anti-A, or immune anti-B. This includes an auto control, an antibody screen and an AGT test with a reagent A1 or B cell against cord serum/plasma. I've tried to get rid of the immune anti-A, -B, but we have a couple of family practice docs who insist that it be included in cord blood workups.  Heavy Sigh!

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An important aspect of this conundrum to remember is that physicians do not treat newborns just because of a positive DAT, they treat infants who are anemic or hyperbilirubinemic regardless of the DAT results.

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10 hours ago, Dansket said:

An important aspect of this conundrum to remember is that physicians do not treat newborns just because of a positive DAT, they treat infants who are anemic or hyperbilirubinemic regardless of the DAT results.

This should be true, but then it brings up the question I have asked before, which is why do they order the tests if it doesn't affect patient care?  I have asked our Peds physician group and received no answer.  Before this year we never did a cord blood workup unless it was to determine RhIG eligibility for mom or the baby was jaundiced.  This year, however they are insisting on all O Pos moms as well.  Of course they didn't tell us this, so we were caught off guard and short of supplies for DATs.  When I asked for the evidence on which this decision was based, I was flatly ignored.

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3 hours ago, BankerGirl said:

This should be true, but then it brings up the question I have asked before, which is why do they order the tests if it doesn't affect patient care?  I have asked our Peds physician group and received no answer.  Before this year we never did a cord blood workup unless it was to determine RhIG eligibility for mom or the baby was jaundiced.  This year, however they are insisting on all O Pos moms as well.  Of course they didn't tell us this, so we were caught off guard and short of supplies for DATs.  When I asked for the evidence on which this decision was based, I was flatly ignored.

I had a similar experience when a Family Practice Dr, who was chair of the OB committee at that time, brought back the Immune Anti-A, -B test.  The only 'reference' he offered was his experience with his children. We wanted to ask if those tests affected how the infants were treated, but refrained....tongue biting was involved. The pediatricians say they don't need the test.

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On 8/14/2019 at 1:17 PM, Malcolm Needs said:

But Dad and baby could both be incompatible with mum major side.  E.g.  Mum could be group A and Dad and baby group B, or have I read this wrong (it wouldn't be the first time)?

Yeah - sorry - I was just assuming it wasn't an obvious problem like that.  When nothing else makes sense and the baby is still in trouble - that is when you are thinking about that rare antibody.

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it would be interesting to see how many "O" moms had Immune anti-A,-B in the cord specimen, regardless of baby's type.

If the test is positive, aren't you forced to assume that A or B is the ab causing the DAT? 

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We recently had baby with strongly positive DAT on cord blood, Mom and baby both Group O, mom had a negative antibody screen at delivery. So,  per policy, did eluate and identified anti-Cw in eluate. Went back and tested mom - who had unidentified anti-Cw demonstrating at delivery.  Our screening cells do not routinely have cell positive for Cw antigen.  Textbook case.

We routinely call baby's location when we have a positive DAT on a cord blood evaluation. This is at the request of the physicians so that they can order a Bilirubin sooner than the routine 24 hrs post-delivery.  This was after many meetings with Risk Management, OB physicians, pathologist, nursing, etc..... This is NOT considered to be a critical value notification.  We call it "abnormal result notification".

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This case worries me.

The screening cells in the UK also do not have to express the Cw antigen, and yet there are several examples of anti-Cw appearing in the literature where the antibody is blamed for severe (and, in at least one, if not two, fatal) HDFN.

Those mentioned by Geoff Daniels (in Daniels G.  Human Blood Groups.  3rd edition, 2013, Wiley-Blackwell) include:

Lawler SD, van Loghem JJ.  The Rhesus antigen Cw causing haemolytic disease of the newborn.  Lancet 1947; ii: 545-546.

Kollamparambil TG, Jani BR, Aldouri M, Soe A, Ducker DA.  Anti-Cw alloimmunization presenting as hydrops fetalis.  Acta Pediatrica 2005; 94: 499-507.

Byers BD, Gordon MC, Higby K.  Severe hemolytic disease of the newborn due to anti-Cw.  Obstet Gynecol 2005; 106: 1180-1182.

May-Wewers J, Kaiser JR, Moore EK, Blackell DP.  Severe neonatal hemolysis due to a maternal antibody to the low frequency Rh antigen Cw.  Am J Perinat 2006; 23: 213-217.

Chu H-P, Kanagalingam D, Chan DKL.  Severe intrauterine hemolysis due to anti-Cw.   Am J Perinatol 2007; 24: 623-626.

A further case is Macher S, Wagner T, Rosskopf K, Reiterer F, Csapo B, Schlenke P, Klaritsch P.  Severe case of fetal hemolytic disease caused by anti-Cw requiring serial intrauterine transfusions complicated by pancytopenia and cholestasis.  Transfusion 2016; 56(1): 80-83.

I would, therefore, be far happier if the Cw antigen were expressed on both UK and US screening cells (as I believe it is in Finland and Latvia).

 

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