I was asked to find out what people are doing about positive DAT's (IgG) that are not associated with transfusion. We receive a few out patient samples that are sometimes positive. We do no further work up. When we receive cord blood speciemens that have a positive DAT, we do not do any further workup unless requested by the physician. Are you guys automatically getting a full patient history and doing an ABID/elution on ALL your positive DAT's, or just the ones that are intended for transfusion? I feel the need to say that we do full work ups on all positive DAT's for transfusion.

Thanks

Teresa

Obviously, as a Reference Laboratory, we only receive such samples "second hand" from the hospitals, but, back in the days when I used to work in hospitals (about the time Landsteiner described ABO), we used to work up such patients at least once, just to ensure that no nasty underlying alloantibodies were lurking around, so that, should the patient require blood, we would not have any unwanted surprises at the last minute.

..... back in the days when I used to work in hospitals (about the time Landsteiner described ABO),

hahahahhahahahahaha!!!!! that would make you > 100yo!!!!

Believe me Liz, there are days when I feel like it too!!!!!!!!!!!!!!

Most of my docs want a workup. Some of the hospitals I do DATs for do not.

We usually will call and ask if they want it worked up. Most of the time they don't.

When we find a positive DAT on a cord blood, we assess the situation and, if all criteria are met (Mom and baby are different ABO types; Mom has negative antibody screen) we report a presumptive ABO incompatibility, with no further w/up unless ordered by the physician. Occasionally the Mom has another antibody and, if there is only the one ab identified and the baby is antigen positive, we report that the positive DAT is presumptively due to the specific antibody. In more complex cases we would send the DAT out for elution.

Adult samples with a positive DAT are sent to the reference lab for a workup. At least one CAP inspector gave us to understand that the expectation is for all positives to be worked up but in our small hospital we only have a few positives per year and find it too expensive to do our own investigation.

Wow, I am impressed with the rapid response, thanks everyone.

I think the Tech Manual has some recommendations on the extent of testing. Our oncologists don't seem to have any need to have us work up pos DATs so we don't unless transfusion is imminent. I am not sure that the results of further testing would make them change their treatment of the patient so it is hard to justify the cost.

Hi Mabel,

I looked at the TM 17ed and it says "Clinical considerations together with laboratory data should dictate the extent to which a positive DAT is evaluated."

We only do an elution if the patient has been transfused within the last month. We do , however, do elutions on all patients under 4 months (initial testing anyway). I've attached our flowsheet - hopefully that helps. [ATTACH]610[/ATTACH]

Well, Teresa, the TM was a bit vague there wasn't it? Seems like there used to be more info but that could have been 6 editions ago.

If DAT is positive: 1) ordered by physician, we perform elution 2) if DAT done as reflex test to positive AC, we perform elution 3) on CORD, check mother's history and if mother's screen negative---do not do elution(unless mother's blood type is same). If mom's screen positive, do an elution.

For a cord , if mums screen is positive, is there any need to do an elution still? Surely the antibody that is causing the DAT to be positive is the one that came from the mother. So if the mother has anti-K, then just report as DAT pos due to maternal anti-K. That`s what we do anyway.

For a cord , if mums screen is positive, is there any need to do an elution still? Surely the antibody that is causing the DAT to be positive is the one that came from the mother. So if the mother has anti-K, then just report as DAT pos due to maternal anti-K. That`s what we do anyway.

Not necessarily a need to do an elution but would suggest it be reported out as likely or probably due to maternal anti-K. If you didn't elute and test, you really don't know. Otherwise it's like stating/reporting a neonate is group O simply because both (reported) parents are group O without testing the infant. Likely, probable, but not sure unless you do the test and can prove.

But I do really know. In my example, if mother and baby are same group, what else could it be but an antibody, anti-K, from the mother? I think it`s a waste of time, money and reagents to do an elution in these cases.

But I do really know. In my example, if mother and baby are same group, what else could it be but an antibody, anti-K, from the mother? I think it`s a waste of time, money and reagents to do an elution in these cases.

OK then, can you please select and tell us all the winning numbers for the next lottery drawing--please be specific for which lottery and what date! Sorry but you still don't really "KNOW". Possibly anti-Kpa, -Jsa, -Cw, -Yt.....could be any antibody reacting to a low incidence antigen that just happens to be present on the same screening cell as the K. Low incidence scenarios also more likely or more plausible considerations with mom-babe situations (providing same father for previous gestations). I wasn't suggesting the need to do an elution, but just to qualitfy your reporting. Likely, probable, but not SURE. Many possiblities.

So has anyone ever had this scenario in a routine hospital blood bank? A mother with a known antibody but an elution on a baby turns up a different antibody? I know Malcolm will probably have seen this in the ref lab, but I wonder how many times. Anyway, our reporting has now been officially amended to say: DAT Positive PROBABLY due to maternal anti-K. That should keep the accreditation inspectors from my door. I still won`t do elution though. As a large maternity hospital I would be doing 5-10 a day if I did.

By the way, UK lottery on Wednesday 7th March. Winning numbers are 2.8.10.19.26.36. You heard it here first!

By the way, UK lottery on Wednesday 7th March. Winning numbers are 2.8.10.19.26.36. You heard it here first!

I'll keep you to those BoroCliff. Share if I win. Send you the bill if I don't!!!!!!!!!!!!!!!!!

Ahh, but we need to know the lucky numbers BEFORE the lottery drawing...kind of like the antibody. Believe me, I respect the inspectors but I'm also related to patient care and will always challenge on that basis.

Just in case you needed more opinions - we recently had a mother with warm autoantibody with anti-e(hr") (IgG positive and negative with anti-C3d) We were unable to exclude anti-C on a homozygous cell but had several heterozygous cells negative in solid phase, gel and tube (she was C negative). Baby delivered via C-sectionwith a positive antibody screen showing a perfect anti-C and no other reactivity.

Was it an autoanti-e or an allo?

I should have been more clear - warm auto with little e specificity - she was e positive

Was it an autoanti-e or an allo?

If we receive an order for a DAT, we report it out as Pos or Neg and leave it up to the physician to order further testing. Most of the times they suspect it will be positive if the pt has a hemolytic disease process. For babies, if mom has a negative antibody screen and we can explain it by ABO incompatible blood types [Mom is O baby is A or B] then we are done. If not, then we will do an eluate to see what is coating baby's cells, keep in mind it might be due to a low frequency antibody not on the current screen or panel.