Ask the FDA 2010 Synopsis on AABB Web Site

[Mary**]

:cries:Has anyone read the summary of Ask the FDA 2010 on the AABB web site?

One question that was asked was: does gel crossmatching satisfy the reqirement to test for ABO incompatibility? The FDA said no, because gel does not detect all IgM antibodies.

I retested this, and found that gel detected all ABO incompatibilities.

Does anyone also do immediate spin or electronic crossmatches when doing gel crossmatches for patients that have IgG antibodies???

[Eagle Eye]

This came from CMS too. I am looking for actual reg. from CMS/CLIA as I read this on one the blood bank society news letter.

[David Saikin]

I validated that my gelxm detects ABO incompatiblilty . . . I also discovered that in pts with no detectable ABO isoagglutinins ABO incompatibility is NOT detectable (wouldn't be with IS tube xm either).

[Liz]

We forward-retype the patient and donor by the slide method at the gel major xm step for verification.

[Mary**]

Let me know if you find it. Thanks.

[David Saikin]

The CMS reg is taken from the CFR (I don't remember the exact area but the standard states that the crossmatch procedure must detect ABO incompatibility). Somewhere on this site there is a thread which addresses this.

[Liz]

Yes Dave we had a huge discussion about this here, the thread can be found by a search.

[Mabel Adams]

I groaned when I heard of this. I have tried to see if I could prove that since we use the same software for the electronic crossmatch and accept it as an ABO compatible crossmatch, we could justify using that as our "crossmatch" when we do gel xms. I don't think it will fly though, because the algorithms of requiring the second blood type would not be activated if we aren't actually doing an electronic xm. Even if we make it our policy to do 2 types for patients not eligible for e-xm, the software wouldn't stop us if we failed to do this with a gel xm.

So, I think validating that gel xms pick up ABO incompatibilitly at least as well as IS does would be the most efficient way to do this. How many samples have those that have done this tested? Did you seek out weak reverse antibodies or dilute out normal strength samples?

[profbaud]

Immediate spin crossmatching is the only crossmatching that can detect ABO discrepancies. We do electronic crossmatching for patients with no history of antibodies [past or present] and they have 2 blood types on file. We do gel crossmatching for those that don't qualify for electronic crossmatching. This is for detecting compatibility for pts with IgG and some IgM antibodies.

Edited November 27, 2010 by profbaud

[AMcCord]

CLIA inspectors have been instructed to cite those facilities that are not doing an immediate spin crossmatch for ABO compatibility. Got this recently from a lab manager who asked a CLIA inspector the question directly, specifically in relation to using gel for crossmatching.

[Liz]

If you perform the gel/machine/tube crossmatch, run in parallel a repeat Blood Group on slide or other.

[khalidm3]

If you perform the gel/machine/tube crossmatch, run in parallel a repeat Blood Group on slide or other.

Shall we repeat blood group from blood bag segment and recipient sample? We test all blood units for ABO and Rh from segments before releasing to inventory.

We perform ABO and Rh by Gel, Antibody screen by 3 cells by Gel, x-match by Gel for all transfusions. If the blood is required urgent, we omit complete Gel cross match and replace it by IS x-m.

[Liz]

Shall we repeat blood group from blood bag segment and recipient sample? We test all blood units for ABO and Rh from segments before releasing to inventory.

We perform ABO and Rh by Gel, Antibody screen by 3 cells by Gel, x-match by Gel for all transfusions. If the blood is required urgent, we omit complete Gel cross match and replace it by IS x-m.

Yes I use the segment from the donors bag and the recipients sample to repeat the Blood groups at the time that I perform the crossmatch. Doing Blood group by gel is great. we repaet by slide.

We would have initially already performed 2 types on the recipient at arrival, by 2 techs and 2 methods, so this is the 3rd type.

Do you perform a major crossmatch even if your 3 cells Ab screen by Gel is negative? you can go straight to IS.

[khalidm3]

Yes, We perform major cross match by Gel even antibody screen (3 cells) is negative for all other than stat orders. We do not use slide at all, repeat or urgent blood groups we perform by tube.

[Liz]

You dont need to perform the major crossmatch if the Ab sc is negative. Is it your choice or were you advised by an accreditation agency?

[khalidm3]

It is the choice of our medical director. Several centres in Europe do the same like us.

[Liz]

This is interesting because in my oral exams I may ask: In the case that the Ab Sc is negative and the major Crossmatch is positive, give me 5 reasons why this would be so.....

[Eagle Eye]

Can I try!!!!!!!

1) Patient has antibody against low frequency antigen

2) Positive DAT on donor

3) false positive due to contamination in MTS 2 diluent

4) Drying of IgG cards

5)...........................

[Liz]

Can I try!!!!!!!

1) Patient has antibody against low frequency antigen

2) Positive DAT on donor

3) false positive due to contamination in MTS 2 diluent

4) Drying of IgG cards

5)...........................

Thats good! Thank you for trying.

Now because I tell the students that there was nothing wrong with the reagents, I will need 3 more reasons. anyone?

And one more question: a patient is known to be AB, he is readmitted at a later date and forward grouping is AB but reverse shows a positive reaction with the A reagent cells. Why? several reasons. anyone??? :plotting:

[Liz]

Come on.. these are senior year questions after the BB rotation..

[Malcolm Needs ☆]

Another three suggestions as answers to your first question.

...failed to put the patient's plasma into the screening cell well?

...put in the incorrect volume of patient's palsma and/or screening cells into the well, thus mucking up the cell/plasma ration and ruining the rate constant of the reaction.

...putting the same screening cell (the one not expressing the antigen) into the screening well.

Any good??????????????????

:idea::idea::trash::trash::haha::haha:

[Liz]

No, not good Malcolm... :'( the tests were done properly.

Shall I give the reasons? or wait a bit?

[Malcolm Needs ☆]

Wait a bit - I HATE being beaten!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

:fear::fear:

[Liz]

do not copy from the other thread that I have just replied to.... you know the AB patient with pos cm.

[Malcolm Needs ☆]

Well, of course, there is always anti-A1, but that doesn't give you the three suggestions you require.