Confirming antigen-negative units

[bevydawn]

My laboratory Director is wanting me to cut way back on the anti-sera I keep on hand to antigen type. It just isn't cost effective for us to keep $1000 reagent on hand that we may only use one time, if at all before it expires. In the past, whenever we received an antigen-negative unit from our reference lab, we have always confirmed the unit is in fact antigen-negative upon receiving it. Generally we never ordered antigen negative units unless we were unable to find one in our inventory or it was someone with a combination that was going to make it extremely hard to find compatible units. Does other facilities confirm the antigen-negative units when they receive them? If so, how do you get around it when you no longer have the anti-sera?

[jhaig]

We don't re-check any of our reference lab's antigen testing, but we do perform a full IgG crossmatch in gel for any units being given to a patient with a known antibody.

I don't stock Anti-S or Anti-M anymore for these very reasons. Why keep Anti-S around if you are going to let it expire? You'll run more QC tests on it that you will patients anyway. It also depends a lot on your patient population. If you have active transfusion recipients with Anti-S or something else rare, then keep some Anti-S around.

A full IgG crossmatch with a unit confirmed by our reference lab as being antigen-negative for the patient's corresponding antibody is good enough in our blood bank.

[DANDERS]

We don't re-check any of our reference lab's antigen testing, but we do perform a full IgG crossmatch in gel for any units being given to a patient with a known antibody.

[drsbright]

We stopped re-testing for antigens because we are paying the blood center a premium to do it for us and they affirm their work on paper and tagging the units. As a safety net, we always perform a full Coombs crossmatch between the screened donors and our patients.

It makes no sense to redo the work you are paying someone to do for you.

[L106]

bevydawn-

Several months ago we were exactly where you describe yourself to be. A combination of: 1) outrageous antisera prices and 2) years of repeating the reference lab's antigen testing and never finding an error, led us to feel comfortable to change our policy and not repeat the antigen typings.

As jhaig, DANDERS, and drsbright all mentioned, we perform a full IgG crossmatch for donor units intended for an antibody patient.

Once our special typing antisera supply dwindles down, I will give more thought to which antisera we will want to continue to stock. (Fortunately, our Blood Bank computer system can search and report exactly which antigen typings and how many we have done over the last year or two, so that will help us make our decisions.)

It sounds like almost everybody is going this route, doesn't it? Small wonder, with the prices now-a-days.

[jhaig]

This is all we keep in-house as far as anti-sera goes:

Anti-C

Anti-E

Anti-c

Anti-e

Anti-Fya

Anti-Jka

Anti-K

We have eliminated Anti-S, Anti-M, Anti-Cw, and Anti-P for lack of usage. I'm sure, however, the reference labs will be sure to pass on the rise in costs to our respective facilities.:cool:

[DHarts]

To cut down use of more common antisera like K, C, E, FYa etc, we use patient serum to screen units if antibody is strong enough to do so. We perform an IgG crossmatch first and only antigen test the crossmatch compatible units. In most cases we can cut the number of units antigen typed by at least half.

Dawn

[Packer Banker]

We don't retype the units from the Blood Center either. We just do the AHG XM as well. I'm guessing we'll pare down our supply as well. Our supply isn't the hugest to begin with, and if you consider the likelihood of finding Ag neg units for some of those... it can end up being cheaper in the long run to order pre-screened units from the reference center.

[Packer Banker]

Uggh- I guess I wasn't supposed to hit enter?? (duplicate thread...)

So, has anyone heard about a new manufacturer coming soon? I don't remember who it was I heard of that's coming in to give some competition. That would certainly help drive down the prices!

[Liz0316]

We do not repeat the antigen screening from the reference lab either.

Keep in mind you must do an AHG XM on anyone with a clinically significant antibody.

An old trick is to save your rare expired antisera, in the freezer. When you need to screen, screen with the expired antisera first, then take the negative units only and screen with indated antisera. Then do the full XM.

[mda]

Is it not a requirement to retest the antigen typing in your facility? Getting a crossmatch compatible doesn't assure that the donor units are negative for the specific antigen you need.

[Likewine99]

We do not repeat antigen tests on units received as antigen neg from our blood supplier.

They are AABB and CAP accredited and we have their CLIA license on file. We do an AHG XM on these units when received in the BB prior to issuing to the pt for tx.

We only keep a few of the "common" ones and often times when the pt has 2 antibodies we order ag neg units to save time ($$$$).

[Liz0316]

no, it's not a requirement to retest antigen testing done by the supplier. Just be sure to leave the tag, describing the testing on the unit.

[rcurrie]

Liz' suggestion is great, as long as you confirm reactivity on a "heterozygous" control cell. Some antisera do not store well (thus the expiration date).

I always used patient plasma to help with the screening when I had a lot of it. The positively reacting units can be eliminated quite quickly that way. It doesn't matter how diluted the patient's plasma is- you are only eliminating positively reacting units, not interpreting the units as compatible. Any that do not react with patient plasma can be tested with the appropriate antiserum.

BC

[OPUS104]

I have been told by one of my hospitals that they were "dinged" by Joint commision for not repeating our antigen typing. I thought this was odd since most of our smaller hosp. dont keep hardly any antisera and some of our larger dont keep everything. Anyone know of any Joint Regs? Bob/Stan where are you?

[Melanie]

We do not repeat any antigen typing done by the reference lab. We are looking into alternative sources of reagents at this time because of rising costs. We keep all common antiseras in stock (C,E,c,e,K,k,Fya, Fyb, Jka, Jkb, S, s, M, N and Lea and Leb)

WE use commercial antisera for donor screening and patient testing for all common allos when required by SOP, but, we also save plasma from donors and patients with allo-antibodies in frozen alliquots for those times when massive screening is needed. However, we require a confimration using commercial antisera with controls prior to labeling unit as antigen neg.

[skoopus]

We always retype our units that we get from our reference center unless there isn't any licensed antisera available, and we always do full crossmatches.

My question is, what if the patient's antibody isn't showing? The full crossmatch would come up compatible regardless of the unit's phenotype.

We try to screen for as many patients as possible and only go to our reference center for units that are hard to find, such as Fya/Fyb neg, e neg, or other rare combinations.

[rcurrie]

Of course, the patient plasma you use for unit screening needs to be reactive. Otherwise, you must use commercial antiserum. I always test the patient's plasma against a cell with a single dose of the antigen. If it is reactive, I trust it for screening. When I find units that are negative with patient plasma, I then test the unit with commercial antiseum to be sure it is antigen negative.

I think most of us long-time bloodbankers have had patients who hemolyzed and when we investigated we found a missed antibody due to the titer dropping off below screen detection level. So, there is always the chance that a patient with a negative screen has an underlying antibody just waiting for antigen exposure. Plus, if you transfuse enough blood, you will dilute out the antibody and have a delayed reaction if the antibody was missed on the screen.

That full crossmatch is just about worthless after you have transfused a full blood volume. We don't even bother- we just give antigen negative blood and go with that.

BC

[GilTphoto]

We do not repeat the antigen screening from the reference lab either.

Keep in mind you must do an AHG XM on anyone with a clinically significant antibody.

An old trick is to save your rare expired antisera, in the freezer. When you need to screen, screen with the expired antisera first, then take the negative units only and screen with indated antisera. Then do the full XM.

This is what we do.

[Mary**]

I agree with the high cost philosphy. We do repeat the reference labs antigen typing if we have the antisera. The only thing that bothers me about not repeating it is the reference lab supplies "historically negative" units without retyping them. Considering the huge numbers of units they have in their computer, I think the chance for a clerical error is an issue.

[rrcc1974]

1. We antigen type red cells if commercial antisera is available.

2. Reference lab documents historical antigen typing and we confirm if we have the commercial antisera.

3. We send specimen or ask for antigen negative red cells and reference lab supplies confirmed antigen negative red cells. (documented on tags attached to units)

[rcurrie]

The issue is whether accepting "historically negative" units without retyping is a reasonable risk or not. The underlying question is whether the unit is from the donor the system says it is from.

No collection-distribution system is perfect. Every time a unit is manipulated in a processing station, it is usually manipulated at the same time as multiple other units. Some processing systems attach a filter after the unit has passed all testing to save the cost of the filter on units that are rejected for one reason or another. This is a point at which units can be mislabeled. Confounding the chances of not catching this error is the habit of processing like ABO units at the same time. Donor A's ABO was A neg prior to filtration, the unit labeled as Donor A tested as A neg after filtration, so it must be Donor A's blood in the bag labeled as Donor A. Anyone who believes this assumption to be true has never worked as QA in a blood processing facility, which I have. There is always the chance that the blood in the bag can't be truly linked back to the donor. Thus, the "historically antigen negative" label is a crap shoot.

That said, the issue will always be whether it was reasonable for you to accept the label as true. I can tell you that a jury would not find it reasonable in a survivor's lawsuit. I did a complete flipflop on my attitude toward risk and liability after two events in my life. The first event was when I had to defend my practices in a wrongful death lawsuit. The second was obtaining my law degree. The rule of thumb is that if you could have prevented an accident, then you will be held liable for the accident if you had a duty of any sort to prevent it. Providing safe blood is one of the highest duties you can imagine. Skimp because of cost, and you will pay the price if something goes wrong. It doesn't matter that you were right 99.9999% of the time.

BC, J.D.

[KathleenSL]

As a blood center IRL, we only send "historical negative" units to those facilities that have antisera (or potent patient antibody) and can do their own confirmatory typings. The historical antigen label/tag on the units clearly states that the typings must be confirmed. Units that have been confirm typed by the IRL have a different label/tag that states which antigens have been confirm typed and if the typings were done using licensed or unlicensed antisera.

[rcurrie]

Thanks for speaking up as a reference lab, Kathleen.

Folks, if you don't have the antiserum to type the unit, then let the reference lab/supplier know and have them type it for you. This isn't about retyping- it is about the initial typing, which is not done when historically antigen negative units are supplied. Reference labs are doing two things when they provide such units: saving time and money for themselves, and saving money for you. You can antigen type cheaper than the charge from the reference lab for such service most of the time.

BC

[Mary**]

I coundn't agree with you more. I lived through one lawsuit and even though we were not at fault, it was a horrible experience and it changed my attitude on a lot of issues. Thanks.

Mary