Antigen typing.....

[silverblood]

At our hospital when we encounter a pateint with a new antibody we antigen type the patient to insure that they are antigen negative for the corresponding antibody. We had a situation with a patient who had been transfused one month ago who developed a new anti-E. Following our policy, the patient was antigen typed for E and was positive. I consulted with out reference lab who told me that the patient's E positive antigen is probably due to being transfused with E positive blood within the last three months. I am now wondering if we should have even done the antigen typing and reported it out in light of the fact that the patient had been recently transfused. Does anyone have protocol regarding this?

[Eagle Eye]

For all patients with recent transfusion history, we do not antigen type as the typing will not be valid. Some time for academic purpose we may type but do not enter in our system.

Did you check for mix field? in your case, reaction might be mix field because patient may have two cell population E+ & E-.

[Malcolm Needs ☆]

For all patients with recent transfusion history, we do not antigen type as the typing will not be valid. Some time for academic purpose we may type but do not enter in our system.

Did you check for mix field? in your case, reaction might be mix field because patient may have two cell population E+ & E-.

I agree.

We ususally leave it three months post the most recent transfusion before we will give a definitive group.

[Brenda K Hutson]

At our hospital when we encounter a pateint with a new antibody we antigen type the patient to insure that they are antigen negative for the corresponding antibody. We had a situation with a patient who had been transfused one month ago who developed a new anti-E. Following our policy, the patient was antigen typed for E and was positive. I consulted with out reference lab who told me that the patient's E positive antigen is probably due to being transfused with E positive blood within the last three months. I am now wondering if we should have even done the antigen typing and reported it out in light of the fact that the patient had been recently transfused. Does anyone have protocol regarding this?

Well, this response is kind of the consolidation of working at 6 different places (including Reference Labs). It may not be a very helpful response, but here goes.

1. If we do perform Antigen Typing on a patient who has been transfused in the past 3 months, we never document

that as their definitive type (i.e. do not enter it in the computer as a permanent record).

2. The "perfect" response would be to say you should not type patients who have been transfused in the past 3

months (in that you don't know if you are typing patient or donor cells).........

THAT BEING SAID...

3. There are times where having a phenotype would really help you with a work-up (as far as your scenario, I would

not have been that concerned with a clear but anti-E; probably would not have bothered to do the Antigen Type;

but I do agree with the premise of performing the Antigen Type as a confirmation to the Antibody ID; kind of like

reverse ABO to confirm forward ABO). I tend to perform Antigen Typing on transfused patients when I am having

difficulty narrowing down the antibody(ies) when it appears there are multiples, and/or, trying to make a decision if

reactions are not hitting all of the cells of a suspected antibody. So I use it in situations where it can be of benefit

for the work-up. However, I think that this should only be done in the hands of someone who is proficient at

antibody ID, who knows they are looking for mixed field reactivity, and has the expertise to know how to interpret

the results they get (to the degree they can be interpreted).

Sorry, that's about the best I can do with that one.

Brenda Hutson, CLS(ASCP)SBB

[L106]

I'm right with Brenda on this one on all her points.

I have it carefully worded that we should not report out any antigen typing on a patient who has been transfused within the last t months, and that any typing performed on such a patient must be carefully evaluated by the Blood Bank Supervisor (ie: me, and I will consider all the things Brenda mentioned, but probably still not actually report out the results.)

[lateonenite]

I'm with everyone else here, we only phenotype if the patient has not been transfused in the last 3 months. Obviously when the three months is nearly up, we might try it - although with a number of ours they're transfusion dependent anyway. D'oh.

[cplatt36]

Question on subject. If you perform an antibody ID is it required that you actually prove the patient to be antigen negative, or is it ok to just make sure the donor cells are antigen negative and IAT crossmatch compatible. I ask this as we are starting to do antibody identifications using gel after 2 years of not doing ID's.

We are part of a 5 hospital system and our large main hospital supplies us our blood. Would it be reasonable to do the ID, not antigen type the patient, and have the main hospital antigen type our units from segments at there facility, perform gel IAT crossmatch of the antigen negative units, and then transfuse. The antigen typing could be done on the patient later by sending cells to the main facility.

Thoughts??

Edited February 24, 2010 by cplatt36

[Malcolm Needs ☆]

Question on subject. If you perform an antibody ID is it required that you actually prove the patient to be antigen negative, or is it ok to just make sure the donor cells are antigen negative and IAT crossmatch compatible. I ask this as we are starting to do antibody identifications using gel after 2 years of not doing ID's.

We are part of a 5 hospital system and our large main hospital supplies us our blood. Would it be reasonable to do the ID, not antigen type the patient, and have the main hospital antigen type our units from segments at there facility, perform gel IAT crossmatch of the antigen negative units, and then transfuse. The antigen typing could be done on the patient later by sending cells to the main facility.

Thoughts??

When a patient is transfusion dependent, and has been transfused before you see them, then this is about the only thing you can do (unless you have access to genotyping).

In such cases, we always tell the hospital to assume that the antibody is an alloantibody, and to give antigen negative blood.

:)

[clmergen]

Our smaller hospitals have limited anti-sera. They order antigen negative blood from the supplier and send patient cells to the main hospital for antigen typing. They do their own crossmatching.

[Brenda K Hutson]

When a patient is transfusion dependent, and has been transfused before you see them, then this is about the only thing you can do (unless you have access to genotyping).

In such cases, we always tell the hospital to assume that the antibody is an alloantibody, and to give antigen negative blood.

:)

Well, if you have access to a Reference Lab that does reticulocyte separation, you can get a type on transfused patients (provided they have a high enough retic count). That being said, I don't think it is worth doing that unless your reason for wanting to do a phenotype is due to a complex work-up where a phenotype would really help (i.e. multiple antibodies; warm auto but don't want to do a differential adsorption; etc).

We do not tend to automaticlly perform the Antigen Typing to confirm straight forward antibodies. If on the other hand we have any doubt (i.e. dosage), it can be helpful.

Just a thought about the Main Hospital performing your antigen typing on the units....I definitely feel more comfortable confirming the Antigen Typing at my own facility (our Donor Center does have historic antigen types on the units, but we have had occassions where it was erroneous). On the other hand, I have never been part of a multi-Hospital system so things probably work differently than what I am used to.

Brenda Hutson

[L106]

I reread cplatt36/s post, and I did not get the impression that the situation heshe was describing indicated that the patient had been recently transfused. I interpreted his/her basic question to be: Once we have identified an antibody, is it necessary to type the patient's red cells for the corresponding antigen. (Cplatt36: Please comment or correct me if I am wrong.)

If this was the question, I was always taught that it was good standard practice to do the antigen typing to prove that the patient's red cells lack the corresponding antigen. However, I imagine that many facilities may not consider this step to be mandatory, and I appreciate that a facility may not be able to stock the antigen typing sera. (If clmergen's blood supplier has a proven track record to be reliable, I would feel comfortable with her arrangement.)

Edited February 24, 2010 by L106

[profbaud]

Yes that is true. You can not phenotype a patient that has been recently transfused since you may be picking up the transfused cells phenotype and not the patient's. Our policy is if transfused in the last 3 months, you can't do it. We keep our crossmatch specimen's a month so sometimes we can go back to a pretransfusion specimen to do the typing. Otherwise we just note on the patient's record unable to phenotype due to recent transfusion and hope the patient doesn't come back in for another 3 months then you can do it.

[clmergen]

Our supplier has been proven to be very reliable. And they are doing actual testing not historical types on units that we order. Given the option, generalists at smaller hospitals, who may be covering more than one department, are happier ordering in antigen negative blood. So we pulled most of the anti-sera since it was getting wasted any way. We only type patients not units for the smaller hospitals but we all share the same computer system so it is easy for us to do the tesitng and result it. If a patient has been recently transfused, we evaluate the need to send to the reference lab for antigen typing. For a simple antibody workup we won't but in the case of a recently transfused sickle cell disease patient who needs a complete phenotype then we would.

[L106]

Sounds good to me, clmergen!

[Malcolm Needs ☆]

Any blood sent out by NHSBT has the typing performed on it for that actual donation, if the typing is performed serologically. However, we have just started to type for DOA and DOB (on the grounds that our anti-Doa and anti-Dob typing sera, along with most of the world, are rubbish!), and with these donors being genotyped, we are allowed to genotype on two different occasions, and then send them out as typed from then on, without repeating the molecular work.

:):)

[cplatt36]

You are right, L106, is the testing mandatory or just good standard practice. The patient may be either recently transfused or transfused >120days previously. As for the testing of the donor cells, the main hospital keeps segments of the units that we have in our inventory. They pull the segments and test them for the corresponding antigen and enter in the results in a shared computer system, Meditech magic, the units are then transfused. This happens with historic antibodies that are below detection.