Quiz Time...

Here in the US, lets say that we do a 3-cell screen on a new patient, and we get a 2+ on one cell in gel, which is consistent with anti-C.  We do a panel, and confirm that indeed, the patient has anti-C (and nothing else)  When ordered, we give the patient AHG compatible C antigen negative units.

 

Question A

Four days later on the same admission, after the patient's first screen expires, they are redrawn and again on the screen we get a 2+ on one cell consistent with anti-C.  In order to give blood, do we repeat the panel ID or just give C negative AHG compatible units?

 

Question #2

Six months later, the patient returns and needs two units.  We do  the screen and get a 2+ on one of the screen cells consistent with anti-C.  In order to give blood, do we repeat the panel ID or just give C negative AHG compatible units?

 

Thanks, Scott

In the UK, and as I am working in a Reference Laboratory, I would do a panel every time.  That having been said, when I was working in hospital laboratories (now a decade and a half ago) we would also do the panel every time.  Whether or not this is still true of a hospital laboratory, I don't know, so I will leave that to one of them to confirm - or deny!

Edited November 5, 20159 yr by Malcolm Needs

We do a panel on every new specimen (if the Antibody Screen is Positive.)

 

Donna

Scott our procedure explicitly describes these scenarios.

 

A: If it's possible to confirm the patient hasn't been transfused or pregnant in the last three months, the screen results are consistent, and it's within the same hospital admission - we can forgoe a repeated antibody identification.

 

B: Selected cell rule outs to detect additional clinically significant antibodies.

I do some type of ID every time if the screen is positive: a complete panel on first admit; selected cells thereafter.

We would do a selected cell panel on any follow up specimen, just to make sure there is nothing else there.  We do not reconfirm the previous antibody since you have to honor it regardless of its current reactivity.

Same as David and pbaker; after the first time we just do selected cells to look for new antibodies.

Unless things have changed in the past 6 or 7 years, and they probably have, the AABB Standards addresses this quite nicely and when we adjusted our policy to match it more than a few blood bankers in the corporation were convinced that we would have patients dying right and left from transfusion reactions.  I'm sorry that I can't come up with the exact standard but if memory serves it was very close to what David and pbaker do. 

Basically, if I recall correctly, the standard essentially said that once the antibody was ID'd any follow up testing only required enough testing to indicate that no new antibodies had decided to show up.  We interpreted this to mean that the antibody screen (3 cells) still indicated only the anti -  C was showing (hijacking the example above) and all C negative units were AHG compatible.  The theory was that the AHG crossmatch would catch any significant antibodies the antibody screen missed.

Oh, I'm all for what David and pbaker do.  The reason we routine do a full panel on every new specimen that demonstrates a Positive antibody screen is because our laboratory staff rotate working the various lab departments.  Some of the generalists would have a little difficulty picking out the right selected cells, so it is just easier and quicker for them to throw in the entire panel (and they are more comfortable with that, so it's fine with me.)

 

Donna

If the subsequent antibody screen is positive and matches the previous screen in reactivity and strength(and I know screening cell reactions can change position), we do not do another workup within 30 days.  As John said, if that antibody was ruled in accurately and previous antigen negative units were compatible, an AHG crossmatch should catch any new antibody.  If we get incompatible crossmatches, we would perform a panel.

We repeat panels q 30 days unless the ABS or gel crossmatch indicates additional antibodies.  We have the panel order set not orderable in our LIS less than 30 days.  But we can over ride it if needed.

"If the subsequent antibody screen is positive and matches the previous screen in reactivity and strength(and I know screening cell reactions can change position), we do not do another workup within 30 days.  As John said, if that antibody was ruled in accurately and previous antigen negative units were compatible, an AHG crossmatch should catch any new antibody.  If we get incompatible crossmatches, we would perform a panel."

 

 

So even in the case of a recent transfusion, an AHG crossmatch can serve the purpose of detecting any new antibodies (that may be obscured when a screen cell reacts) in the case of a previously screen-detected (and panel ID'd) antibody?

 

Scott

I interpret the AABB standard to infer that you still need to test with reagent RBC for the presence of antibodies that cannot be excluded with negative reactions with your screen. I would not rely on the AHG crossmatch to pick up the anti-K, -Fya, -Jka etc that might hidden in back of that C-pos screening cell that reacts, particularly in the case of a newly appearing antibody that may be quite weak. I would much rather eliminate the antibody through standard techniques with antigens whose encoding genes are, if possible, in a homozygous dose (that verbiage was just in case Malcolm was listening).

That is how I would interpret the AABB regs in the US as well.  However, I think it is interesting that there is a significant variance in opinion on P&Ps here concerning the meaning of the regs, and subsequent application to routine work in a transfusion service.

 

Scott

I interpret the AABB standard to infer that you still need to test with reagent RBC for the presence of antibodies that cannot be excluded with negative reactions with your screen. I would not rely on the AHG crossmatch to pick up the anti-K, -Fya, -Jka etc that might hidden in back of that C-pos screening cell that reacts, particularly in the case of a newly appearing antibody that may be quite weak. I would much rather eliminate the antibody through standard techniques with antigens whose encoding genes are, if possible, in a homozygous dose (that verbiage was just in case Malcolm was listening).

 

He was!.......and he agrees with all that you say.

 

The thing about detecting a de novo clinically significant antibody in the cross-match is that you cannot guarantee that you will.  Take, for example, an anti-Jk^a.  A de novo anti-Jk^a may only be detected by red cells expressing homozygosity for the Jk^a antigen, and there is no way of knowing that the units being cross-matched are Jk(a+b-), Jk(a+b+), Jk(a-b+) or even Jk(a-b-), unless they have been typed for those antigens.  The other thing is, as I have said on this site many times before, the preservative in the unit of blood is designed to keep the oxygen carrying capacity at an optimum, whereas this preservative will not keep the expression of the antigens at an optimum.

 

Screening red cells, and antibody identification panel red cells, are selected for the antigen strength expressed, and the preservative used is designed to keep that expression at an optimum, but is not designed to preserve the oxygen carrying capacity.

I would not repeat the panel in either case unless the C negative, AHG crossmatched units were incompatible OR the antibody screen showed additional reactivity or increased strength.

Obviously this is open to differing interpretations.  Sorry folks but you are dealing with biological systems here and there are NO 100% guarantees on anything.  The best we can do is play the odds and base decisions on the level of our individual paranoia.  There is no test that will always detect every antibody at every level, it does not exist.   For every decision there is always the "but what if" which will come up and drive you crazy if you let it.  There are reasons most of the standards are written to leave room for interpretation, it's because even the folks tasked to writing them could not agree on what they wanted.  Obviously I had no problem with my interpretation, if you do, then do something else.  As long as it's within the broad guidelines your need for CYA should be met.  Let the uproar begin. 

In the US, the AABB standard reads:

 

5.14.3.3 In patients with previously identified clinically significant antibodies, methods of testing shall be those that identify additional clinically significant antibodies.

 

Scott

Edited November 12, 20159 yr by SMILLER

Obviously this is open to differing interpretations.  Sorry folks but you are dealing with biological systems here and there are NO 100% guarantees on anything.  The best we can do is play the odds and base decisions on the level of our individual paranoia.  There is no test that will always detect every antibody at every level, it does not exist.   For every decision there is always the "but what if" which will come up and drive you crazy if you let it.  There are reasons most of the standards are written to leave room for interpretation, it's because even the folks tasked to writing them could not agree on what they wanted.  Obviously I had no problem with my interpretation, if you do, then do something else.  As long as it's within the broad guidelines your need for CYA should be met.  Let the uproar begin. 

 

Rabble rabble rabble !

 

In the US, the AABB standard reads:

 

5.14.3.3 In patients with previously identified clinically significant antibodies, methods of testing shall be those that identify additional clinically significant antibodies.

 

Scott

 

 

We determined our procedure based on our own experience and a creative interpretation/application of AABB 5.14.3 in general.

If you read 5.14.3.2 it says:

 

"If the patient has been transfused in the preceding 3 months with blood or a blood component containing allogeneic red cells, if the patient has been pregnant within the preceding 3 months, or if the history is uncertain or unavailable, a sample shall be obtained from the patient within 3 days of the scheduled transfusion. Day 0 is the day of draw."

 

We complete our requirements for standard 5.14.3.3, with the initial specimen:

 

"In patients with previously identified clinically significant antibodies, methods of testing shall be those that identify additional clinically significant antibodies."

Right, so the fact that the patient has been recently transfused (or pregnant) does makes a difference?  You wouild do another panel to r/o additionals in that case?  I think many here have posted that that is thier policy.

 

Scott

We panel monthly unless the patient has recently been transfused or is pregnant - then we repeat the panel.

Yes Scott, the transfusion history or pregancy does have an impact on how the work on a patient is to proceed.  First, as has been mentioned here, is the frequency of collection of the sample which I won't get into as it has been addressed.  Second, the frequency in which you perform an antibody identification/rule-out is dependent on the patient's history.

 

If the patient has been transfused or pregnant within the past three months, then a panel should be tested in the face of a positive antibody screen as long as a new sample is required (the date of the new test is outside of the "three days" (actually 4) of the previous test as allowed by the Standards).  You do not have to re-identify a known antibody, but you must make sure a new antibody has not developed.  In my opinion, a compatible crossmatch fails to meet the criteria for identifying a newly formed antibody as I am sure the donor's phenotype is not known therefore the criteria set forth in the Code of Federal Regulations can not be met.  A compatible crossmatch does not equal a nonreactive antibody panel!

 

If you have previously ID'd an antibody and the patient does not get transfused and has not been pregnant or transfused within the prior three months, then technically, that ID stands for the next admission....as long as the new screen reflects what was previously identified.  Obviously, if you ID'd an anti-K and a K- cell comes-up positive in the screen, then it would be wise to perform a panel to ID the unexpected reactivity.  Of course, in this scenario it would be wise to have full faith in the patient's ability to communicate accurately whether or not they have been transfused at another facility.

 

A bit wordy...sorry.

 

 

We limit the waiver of repeated ABIDs to same admission only.