I like to know whether a negative crossmatch by gel technology alone taken as sufficient crossmatch for transfusing red cells. Assuming that atypical antibody screening done again by gel technique. Recently I came across a sample which did not show any atypical antibodies by gel but did show saline reactive Anti A1 antibody reactive at 37 .C . Gel did not pick up this. Is it necessary to do saline crossmatch in addition to gel cross match ?

SPS

In the US at least, it is absolutely necessary. I believe it has to do with the idea that gel (or any AHG method),cannot by itself, guarantee ABO compatibility.

GEL and Solid phase (ECHO) crossmatchs are designed to detect IgG AHG inompatibilty, not ABO incompatibility.

For sites that only do Electronic Crossmatches, how do you address this possibility of ABO incompatibility?

Your electronic crossmatch is essentially a computerized ABO check.

Your electronic crossmatch is essentially a computerized ABO check.

Understood. But the situation presented by the O.P. would be missed by the electronic crossmatch.

Should an unexpected anti A1 not be detected in the reverse typing?? I have discovered many in my career but never at the time of crossmatch always when my forward and reverse types did not match and further investigation was warrented.

I have never seen a clinically significant anti A1. I know they are out there but I don't worry about them. I am more worried about a Kpa or Jsa that I could be missing with my screening cells. You can only do so much.

R1R2

My techs are a little paranoid about missing something (not always a bad thing but sometimes they go a bit overboard). I tell them that we can only test to the best of our ability and let God take care of the rest.

I like to know whether a negative crossmatch by gel technology alone taken as sufficient crossmatch for transfusing red cells. Assuming that atypical antibody screening done again by gel technique. Recently I came across a sample which did not show any atypical antibodies by gel but did show saline reactive Anti A1 antibody reactive at 37 .C . Gel did not pick up this. Is it necessary to do saline crossmatch in addition to gel cross match ?

SPS

At my hospital, we do IS (buffer card) and AHG phase (IgG card) crossmatches with gel when the crossmatch if a full crossmatch. The IgG card only detects antibodies reactive at 37. It is also stated in the package inserts for the gel cards. Also, the Anti-A1 should be reactive with the reverse phase of the typing.

Just went through this recently. My manager and I feel strongly that, as long as our validated computer system is designed to pick up and block ABO incompatible products from being associated to a patient (we do computer crossmatches here) we should be able to use the gel crossmatch alone for patients who require it. However, our regualtory agencies do not see it that way. And because of this, the software company feels they have to recommend an IS phase each time a gel xmatch is done. The basis of this issue is that the labeling of the gel cards indicates that it is not approved to detect ABO incompatibilities. Yet, every day we qc our MTS diluent by performing one ABO incompatible and one compatible crossmatch in gel, and they have always worked. So,we are now performing an IS crossmatch with every gel crossmatch we do.

what computer system do you have?

what computer system do you have?

Cerner Millennium

I should add that all recipients are typed at least twice on separate draws, and of course the unit types are confirmed at receipt.:juggle:

I like to know whether a negative crossmatch by gel technology alone taken as sufficient crossmatch for transfusing red cells. Assuming that atypical antibody screening done again by gel technique. Recently I came across a sample which did not show any atypical antibodies by gel but did show saline reactive Anti A1 antibody reactive at 37 .C . Gel did not pick up this. Is it necessary to do saline crossmatch in addition to gel cross match ?

SPS

Here's a copy of FDA and CLIA transcript regarding this topic...hope it helps

Question 4: We perform all routine testing using gel technology. We also perform electronic crossmatches. For patients in whom clinically significant antibodies have been identified, is it sufficient to perform only a gel antiglobulin crossmatch? Does this satisfy the CLIA requirement to perform a test to detect ABO incompatibility?

MS. MEYERS: For this question, before I start, I would like to just make the comment that the answers that I will be giving to the questions today are based on the CLIA regulations. However, I would like to remind the audience that many laboratories choose to obtain their CLIA certification through a CMS-approved accreditation organization, of which there are six. One of which is AABB. These laboratories must follow all the requirements of their chosen accreditation organization which may be more stringent than the CLIA requirements.

Now back to the question. Actually, these CLIA requirements for crossmatching are based on the FDA requirements for crossmatching, and FDA and CMS have collaborated in preparing the answer to this question. The simple answer is that the IgG gel card does not fulfill the requirement to demonstrate ABO incompatibility. There are two issues involved here. First, the labeling clearly indicates that the IgG gel card is for direct and indirect antiglobulin tests. In other words, detection of cell-bound IgG antibodies. While the limitation section of the package insert states that some IgM antibodies may react, this limitation should not be interpreted to mean that the card is capable of detecting all IgM antibodies, particularly ABO antibodies. Secondly, the IgG gel card is a low ionic test system and there have been reports that ABO incompatibilities, due to IgM antibodies, can be missed when the antibodies are weak and the test is low ionic strength. While we acknowledge that there is continuing debate on this topic, but with the knowledge of these reports and in the absence of data from the reagent manufacturer to support the use of a low ionic strength system for detection of ABO incompatibility due to IgM antibodies, we believe it is not appropriate for users to omit some kind of test to detect these incompatibilities. And for eligible patients, an electronic crossmatch would fulfill the requirements. An immediate spin crossmatch, of course, is an acceptable method for all patients.

MODERATOR: Thank you, Penny. Can I ask, because I could not hear everything that you just said, but did you respond to the part about sufficient to perform only the gel antiglobulin crossmatch, that first part?

MS. MEYERS: No, it is not sufficient to perform only the gel antiglobulin crossmatch because that does not fulfill the requirement to detect ABO incompatibilities.

We also perform immediate spin crossmatches with the gel.

The FDA and CLIA position is understandable as far as it goes but, does anyone else on this discussion feel that, the gel crossmatch in conjunction with a computer system designed to prevent ABO incompatible products from being given should be just as effective as a gel crossmatch in conjunction with an IS crossmatch?

I don't want to prevaricate, but YES!

The way I understand it, the point of the IS with a IgG gel Xmatch is to cover a possible IgM ABO incompatibility that might otherwise be missed (as explained above). If a faciliity uses an electronic crossmatch it seesm like you would be covered.

Scott

I would also like to simply say "YES" . The FDA always gives a "dump truck load" of explanation when answering a question. A patient-product compatiblity program that prevents an ABO incompatible RBC from being crossmatched and issued when performing an electronic crossmatch, is acceptable in place of a saline phase crossmatch.

I like to know whether a negative crossmatch by gel technology alone taken as sufficient crossmatch for transfusing red cells. Assuming that atypical antibody screening done again by gel technique. Recently I came across a sample which did not show any atypical antibodies by gel but did show saline reactive Anti A1 antibody reactive at 37 .C . Gel did not pick up this. Is it necessary to do saline crossmatch in addition to gel cross match ?

SPS

Sure according last standered of AABB if the antibody screen is negative you could issue blood by using one of three; immediate spine cross match, full AHG cross match or electronic cross match, and mostly antibdies interfere with IS cross match are insignificat execpt anti A, anti B or anti AB, also note that anti A2 is insignificant.

At my lab we depend on IS cross match if antibody screen was negative, but for us to be more sure if IS is positive we switch to AHG cross match.

anti-A2? Do you mean anti-A1? I have a patient with a clinically significant anti-A1 so . . . . . . . anti-A1 is not always insignificant.

anti-A2? Do you mean anti-A1? I have a patient with a clinically significant anti-A1 so . . . . . . . anti-A1 is not always insignificant.

Yes, I'm sorry I mean anti A1, but it's mentioned clearly in AABB TM 17th edition anti A1 is clinically insignificant.

Thanks

Just proves that there are no absolutes....

When we receive a specimen, we do blood type use gel card which show the forward and reverse type, we use A1 cells to do the reverse type, so if there is any inconsistent we will see and it include anti-A1.

Then we do antibodies screen use gel, and crossmatch use gel or polybrene .

We do like this for more than 10 years , we have not see any transfusion reaction.

The FDA and CLIA position is understandable as far as it goes but, does anyone else on this discussion feel that, the gel crossmatch in conjunction with a computer system designed to prevent ABO incompatible products from being given should be just as effective as a gel crossmatch in conjunction with an IS crossmatch?

Computer crossmatches do not apply to those patients with Antibody (current/previous) or ABO typing discrepancies, use serologic crossmatch techniques for compatibility testing.