At my current organization, if we have a patient who has had a previously identified antibody we do not run an antibody screen on them first. We immediately go to a modified antibody identification. At all of the other places I have previously worked, we have always ran an antibody screen first regardless of the patient having a known antibody or not. I feel we should be running a screen first always but I am wondering what other people do in this situaiton. Please share.

 

When working in a hospital laboratory (admittedly 15 years ago now), we ALWAYS performed an antibody screen.  As much as anything, this would give us a clue if there was a "new" antibody present, that may have been obscured by the original antibody in the panel.

 

In the Reference Laboratory where I have worked for the last 15 years, we do not screen the plasma at all (on the grounds that the hospital wouldn't/shouldn't have sent it to us unless and antibody had been detected), but we make CERTAIN we cover all bases with our panels, using multiple panels (and rare cells) if necessary.

We always run a screen.  First, for the reason Malcolm mentioned.  Also, in the case of some antibodies, the titer may have dropped to nothing over time, in which case a panel may be a waste of time.

 

And besides, you may have a few more cells to use along with the panel to finish rule-outs!

 

Scott

We usually run the screen but if it is a recurring pt we may just run selected cells to r/o other specificities which may have developed. Saves the pt a bit of money and time if they are getting transfused the day of the specimen.

We perform a screen first (for the same reasons as SMILLER cited.)

 

Donna

We always do a screen; if positive, we go to selected cells to look for new stuff.

Thank you for this valuable information.

If working in a hospital, I guess I'd make my decision based on how often I end-up doing a panel, or an abbreviated selected panel, after confirming the previously known antibody is still reactive.  Just taking a wild guess, I'd imagine that is the majority of the time.  If so, then it seems to me that it would be more cost effective just to start with a selected panel.

 

Agree with David.  

We always run a screen first as well.  I LIKE the idea of running a selected panel only, but... we are a core lab.  I feel like every time you modifiy or change a routine practice you are looking for trouble.  So, we keep it as is

s

I like StevenB's answer.  Like most above, we always do a screen first.  However, A select cell panel that rules out everyting significant and includes at least 1 cell containing the antigen of the known antibody (proving reactivity), technically could be considered a "screen" could it not?

While I like to include a cell ag positive for a known ab (actually I like to run ones with a homozygous and heterozygous expression), it seems a moot point in that even if these cells are negative you are still going to give ag negative blood. As I do a lot of reference abid's sometimes the plasma is too precious to "waste" on a known positive cell.

We also run a screen too - sometimes the antibody has fallen to a titre too low to detect. No point wasting time and energy doing a panel when you can just bung it on the analyser

BUNG IT?

"sometimes the antibody has fallen to a titre too low to detect".  This is a common statement regarding this topic.  How often is "sometimes"?  1 in 50? 1 in 20?  1 in 10?  Let's go with the latter...

 

If 10% of the time a hospital sees a patient with a previously known antibody that is no longer detectable, that means that 90% of the time they are performing an unnecessary test as the screen will be positive and additional testing is required.  Doesn't this seem a bit odd?  More importantly, under this scenario, 90% of the time charges are being generated that are unnecessary.

 

I think the 1 in 10 scenario is actually a conservative figure considering the common use of Gel screening which is one of the most sensitive test methods blood bankers use.

 

Personally, I think my focus would be more on what is more likely to occur than what may occur.  That doesn't mean I'm right, it just is the approach I'd use.

"sometimes the antibody has fallen to a titre too low to detect".  This is a common statement regarding this topic.  How often is "sometimes"?  1 in 50? 1 in 20?  1 in 10?  Let's go with the latter...

 

If 10% of the time a hospital sees a patient with a previously known antibody that is no longer detectable, that means that 90% of the time they are performing an unnecessary test as the screen will be positive and additional testing is required.  Doesn't this seem a bit odd?  More importantly, under this scenario, 90% of the time charges are being generated that are unnecessary.

 

I think the 1 in 10 scenario is actually a conservative figure considering the common use of Gel screening which is one of the most sensitive test methods blood bankers use.

 

Personally, I think my focus would be more on what is more likely to occur than what may occur.  That doesn't mean I'm right, it just is the approach I'd use.

I agree StevenB. And I think the odds are much lower. I calculate 1 in 5,000.   In all my years of reviewing patient's antibody hx carefully and going right to select cells when appropriate,  I only had one instance when antibody was no longer detectable and I found a worthless Lua  in the process. 

I feel like we must be an outlier then because it's almost surprising for us when many patients express antibodies. When you factor in the multiple antibody patients, I would pose that easily more than 1/3 of the samples we work on with patients with previous history of antibodies will not be demonstrating at least one antibody if not more. This is obviously entirely anecdotal but you've raised my curiousity.

But then the antibody screen is useful to eliminate antibodies and make the panel easier to read.

We are going to change next week to doing "selected cell panels" on patients with previous antibodies.  I don't care if the antibody is still there, since we will honor it regardless of reactivity.  I just want to know if there is anything "new".  Why would I want to run an entire panel when I could do the same thing with 3 or 4 cells?

_{We ALWAYS run a screen first, why expend the time and reagents to perform the ID when there is nothing to ID.}

Our policy is to perform antibody screen. If the pattern matches the historical antibodies on file (positive cells are for that previously identified antibody) and there is at least one negative cell, then we crossmatch antigen negative units. We do not repeat the panel unless there is evidence of a new antibody - positive screen cell that is antigen negative for the known antibody; or incompatible crossmatch with antigen negative blood. Then we have option to run entire panel or do selected cell panel.

An antibody screen result from a current sample has to be entered into the LIS in order for us to result crossmatches in the LIS.