Frequency of Antibody Identification

[LindseyN]

When you have a patient that is in-house, not getting transfused but having Type and Screens performed every 3 days how often to you perform the Antibody ID? Is it necessary to re-identify the antibody with every specimen if we know that patient is not getting transfused?

[SMW]

Once you identify an antibody, it is never necessary to re-identify the antibody. If clinically significant, you will always honor that antibody even if it is no longer detectable. The purpose of the repeat antibody screen is to determine if new or additional antibodies have developed. You can accomplish that simply by using cells for your antibody screen that are negative for the previously identified antibody(ies) but contain the appropriate representation of other antigens.

[LindseyN]

So are you saying that if you have a positive antibody screen and you ID a specific antibody you do not perform a full antibody ID if you get a new sample in 3 days? We specifically had a case where a woman receive Rhogam so she had a postive antibody screen due to passive D and she was in house being drawn every 3 days. She was not being transfused so it seems a waste to perform an antibody identification each time.

[SMW]

Yes. All you need to do every three days is perform an antibody screen using D-negative cells that contain the other necessary antigens to demonstrate that no additional antibodies have developed. Some panels even mark which cells will accomplish that with the presence of an anti-D. Although passive antibody is a whole different animal, but for immune antibodies you generally never need to "re-identify" an antibody. Even if the patient returns years later, all you need to do is look for any new or additional antibodies, e.g., run a selected cell panel. For example, if you have a patient with a previously identified anti-e and that patient returns years later, as you mentioned it is a waste of time and reagents to run a panel that likely has 9/10 cells e-positive. You would only need to test e-negative cells and perform rule-outs to determine if any additional antibodies are present.

[LindseyN]

That's what we currently do (run selected panel cells for a previously identified antibody). But even that seems redundant if we know that patient has not been transfused.

[SMW]

Did she receive RhIgG because she is (or was recently) pregnant? Pregnancy can also be an immunizing event........

[Malcolm Needs ☆]

Did she receive RhIgG because she is (or was recently) pregnant? Pregnancy can also be an immunizing event........

That is exactly what I was wondering.

You have to remember that a foeto-maternal haemorrhage, even a "silent" one is, in reality, a transfusion of the baby's blood to the mother.

:confused::confused:

[Eagle Eye]

we repeat antibody identification every 8 days unless antibody detection (screening cells) pattern is different. Of course we document this on our form and the form is reviewed by supervisor daily.

[LindseyN]

She did receive Rhogam because she was pregnant.

[PammyDQ]

we repeat antibody identification every 8 days unless antibody detection (screening cells) pattern is different. Of course we document this on our form and the form is reviewed by supervisor daily.

That's basically what we do, however we use 14 days not 8.

[lateonenite]

We do every three days for women of childbearing age and those transfused in the last three months. Everyone else is every ten days.

We've had a couple of cases now where the patient has gone to a private hospital, come back to us and had a subsequent antibody develop from transfusion we knew nothing about in the intervening period (*shudder* at the thought of not ID'ing that one). The best one was ten days in between admissions, the longest about three months.

[LindseyN]

Thanks for the replies everyone! aakupaku and PammyDQ, did you guys do any benchmarking for performing your antibody ID's every 8/14 days? Just trying to get an idea of how many hospitals do this. Thanks!

[PammyDQ]

Gosh Lindsey, good question. I am not a supervisor so all I can say is that was the policy/procedure in place when I came here 8 years ago. That was the policy where I also worked in another state for 12 years. That was the policy at 3 other institutions where I also worked briefly. It never occurred to me to question it as it is routine practice in my experience. I presume some sort of validation was done ages ago. All the instutions are AABB certified and my current facility received 100% in our last 2 inspections! We'll see if that holds up as our next AABB inspection will be tomorrow or Friday!!

Note: If there's a increase in reaction strength on the screen, or if a unit that SHOULD be AHG compatible (ie negative for the antigen to the known antibody) reacts as incompatible, then we would proceed with a full antibody identification workup.

[LaraT23]

We do a full ID if the antibody screen is still positive. There are no exceptions. We repeat patients who are pregnant or have received blood every three days if a product is ordered and we do give a ten day expiration to preop patients who come in at least 7 days before their surgery. In all cases, full ID for positive screens.

[rravkin@aol.com]

It should be noted that even the delivery of the baby can be a sensitizing event so therefore a selected cell panel should be utilized for work-up of the post delivery specimen.