Incompatible?? Units on the echo

[MAGNUM]

Recently, while training a new employee on crossmatches performed on the Echo, I purposely pulled a AB+ unit and attempted to crossmatch it to a A+ patient. The unit should have been incompatible, right?? Not so. So I sent a tech service request to immucor, and the response that I received back was that this is just one of those unfortunate events because the crossmatch is only IgG it would not pick up incompatibilities. I then ran a totally different A+ patient, and lo and behold the unit was 3+ incompatible. I tested the unit against the original unit, and compatible again. Whats up with this? We do perform an immediate spin crossmatch on all crossmatches done on the instrument, and we should detect any incompatibilities at that time, but it just grates on my weak and feeble mind that the instrument will not detect this obvious incompatibility.

Surely someone can give me an answer that I can live with, as it is, I may not utilize the crossmatch capabilities of the instrument.

[jayinsat]

Remember ABO antibodies are primarily IgM. The ECHO crossmatch is IgG and CAN miss IgM incombatilbity. This is why the results upon completion state:"IgG Comp (Check ABO Comp). Your installation Tech/Trainer should have explained this to your super users. When we validated our ECHO, we experienced this as well. It is the Techs responsiblity to ensure the units placed on the instrument are ABO compatible.

Hope that helps.

[Malcolm Needs ☆]

One thing it may be is that the first patient had, indeed, a "small amount" of IgG anti-B (was it a male by any chance?) and the second a "larger amount" of IgG anti-B (was this second patient a parus female by any chance?).

I'm not saying that this is the reason; only that it may be the reason.

[MAGNUM]

First patient was indeed male, and the second female.

[MAGNUM]

jayinsat,

it does help, but still hard to stomach. during validation, we had no instances where we had this happen. the installer/tech trainer did tell us this, but since i had never seen it before i did not let this sink into my brain.

[Malcolm Needs ☆]

Well MAGNUM, there is a very good chance that the male would not have been exposed to too much in the way of the B antigen in nature to have made much in the way of an IgG anti-B.

There is a chance that the second patient, being female, could have borne a group B or AB baby, and would then have had a good chance of making a "higher amount" of IgG anti-B. This would be even more likely if the lady is of African extraction (or her partner is of African extraction), as the B antigen is expressed more strongly amongst the Black ethnicities than the White ethnicities.

I'm still not saying that this is the right explanation, but it may be!

[L106]

Recently, while training a new employee on crossmatches performed on the Echo, I purposely pulled a AB+ unit and attempted to crossmatch it to a A+ patient. The unit should have been incompatible, right?? Not so. So I sent a tech service request to immucor, and the response that I received back was that this is just one of those unfortunate events because the crossmatch is only IgG it would not pick up incompatibilities. I then ran a totally different A+ patient, and lo and behold the unit was 3+ incompatible. I tested the unit against the original unit, and compatible again. Whats up with this? We do perform an immediate spin crossmatch on all crossmatches done on the instrument, and we should detect any incompatibilities at that time, but it just grates on my weak and feeble mind that the instrument will not detect this obvious incompatibility.

Surely someone can give me an answer that I can live with, as it is, I may not utilize the crossmatch capabilities of the instrument.

MAGNUM - This is a known short-coming of the Echo instrument (and we observed it during validation studies.) That is why the Echo always prints the message "IgG Comp: Check ABO Comp" (ie:basically, as a disclaimer.)

Donna

[carolyn swickard]

Quote: MAGNUM - This is a known short-coming of the Echo instrument (and we observed it during validation studies.) That is why the Echo always prints the message "IgG Comp: Check ABO Comp" (ie:basically, as a disclaimer.)

All of the instrument/ systems (occasionally even tube testing) seem to have this IgG/IgM problem. That is why the CAP and AABB inspectors are now looking to make sure you do have Immediate Spin testing for ABO incompatibility to back up any IgG only test system. There was a very large thread on this when Ortho had to let all their customers know that any gel IgG crossmatches had to also have an Immed Spin ABO compatiblity check or had to be backed up by a validated electronic crossmatch capable computer system. Immucor already had it in their training notes and manuals, but I didn't seem to "get" the message either until that Ortho thread came out. You might be able to find it on here.

[R1R2]

Not to get off topic too much, is anyone including an immediate spin when doing a prewarm crossmatch?

[Malcolm Needs ☆]

Not to get off topic too much, is anyone including an immediate spin when doing a prewarm crossmatch?

Of course.

[carolyn swickard]

Not to get off topic too much, is anyone including an immediate spin when doing a prewarm crossmatch?

Yes, we do them, but not in the same tube.