Reasons for Compatible cross match between A+ and B+ blood

[lyla_n]

Recently encountered a case of a B+ patient who when cross matched with A+ blood is compatible.

the grouping for both the samples was run on Tango as well as Techno and also done manually. No discrepancy in forward and reverse typing.

The cross match was also repeated manually. Still compatible. What could be the reasons?

patient is a case of CBD stricture scheduled for surgery.Historical blood group is also B+ and no H/O transfusions in the recent past.

[Desoki]

Did you shech QC of your machine and reagent

[rravkin@aol.com]

Any recent history of bonemarrow transplant?

[Auntie-D]

Why would you even do that?

[R1R2]

Did your manual test include an immediate spin?

[lyla_n]

Why would you even do that?

Thats another problem.. The unit was mis labelled as B+. On rechecking the group it was found to be A+

And yes the grouping was done from segment attched to blood bag.

- - - Updated - - -

No didn do an immediate spin. No H/O bone marrow transplant.

And QC of machine and reagents was done

[David Saikin]

You had better call the manufacturer of your medical device (Tango/Techno) . . . Is it SOP that an immediate spin xm is not performed? Are you in the USA? - if yes, you should also contact the FDA/CBER. . . . and your blood supllier - the would have to submit a BPD report if the unit was mislabelled by them . . . and they are in the USA.

[bmarotto]

Please clarify if the unit was originally grouped as Group A by the Tango/Techno but mislabeled as Group B (i.e. was it clerical error in the labeling of the unit or did Tango/Techno give an incorrect ABO result?). If the patient is Group B and the unit was labeled Group B (incorrectly) and the crossmatch was compatible what made you question the ABO group of the unit? You say there was no forward/reverse group discrepancy (I assume you mean the patient)...if this is the case and you did not do immediate spin crossmatch perhaps the patient's anti-A is not reacting at AHG. Try testing the patient's reverse group at AHG.

[jayinsat]

Thats another problem.. The unit was mis labelled as B+. On rechecking the group it was found to be A+

And yes the grouping was done from segment attched to blood bag.

- - - Updated - - -

No didn do an immediate spin. No H/O bone marrow transplant.

And QC of machine and reagents was done

This is the problem. The automated methods are set up to detect IgG incompatibility, not ABO (IgM) incompatibility. That is why the immediate spin crossmatch is still important (unless you do Electronic crossmatch). However, the bigger issue of the mislabeled unit of blood scares me to death!

When we validated our ECHO, we had a crossmatch that was ABO incompatible test IgG AHG compatible on the analyzer. I don't believe this is wholly uncommon. That is why you must select compatible groups to perform crossmatches on automation. The ECHO actually reports "SEROLOGICALLY COMPATIBLE: VERIFY ABO COMPATIBILITY".

[Eagle Eye]

do you retype your units before putting into inventory?

do you retype units before selecting them for crossmatch?

Then in that case this would have been picked up before crossmatch.

[MAGNUM]

as I have found out in a previous thread. thanks James

[EDibble]

When we barcode our units into inventory (our supplier is ARC), we barcode the ABO Rh that is on the bag. When we retype the units, and put the results in the computer, if the tested result(s) do not match what they should be according to original labelling, it flags us and we have to resolve the discrepancy.

For most patients, we perform electronic crossmatches, but the computer system will not let us choose ABO incompatible blood.

[tbostock]

The Tango only tests compatibility at the AHG phase. If the patient doesn't qualify for electronic, then the immediate spin crossmatch (which we do on bench manually) would be very positive. Both phases (IS and AHG) are necessary.

[galvania]

Before everyone goes off at a tangent, it is important to note that the manual crossmatch was also compatible. Even though the Coombs cards are not as effective at picking up ABO incompatibilities as immediate spin, they still normally do pick them up. I would suggest you look at the patient's levels of anti-A by tube. It could be that it's so low that that's not picking up either. I would also you suggest measuring his total levels of IgM and proteins in general. There are a number of reasons why his anti-A levels could be undetectable, but I would start with that. As for the unit of blood being mislabelled, that's a totally different issue and the root cause of the error needs to be identified and dealt with - urgently. You don't say what made you query this in the first place..

[sshel55]

That is my question as well (retype on unit). It is known that some ABO incompability will not be detected by the crossmatch test. That is why we have so many other checks in place including the confirmation of the blood group of units after labeling. Perhaps the unit was a subgroup of A which may help explain the compatibility especially if the anti-A titer in the patient was low.

[Mabel Adams]

Yes, I was going to ask if any other A units were tested against this sample.