TRM.40600 antibody screens

[adiescast]

I am reviewing the CAP requirements and noticed in the notes for this question the following comment: " If a laboratory collects an additional sample for the purpose of verification of patient identity, a repeat antibody screen need not be performed on this specimen, unless it will be used for compatibility testing, in which case, an antibody screen is required for the new specimen." (emphasis mine).

When we run out of sample for crossmatching on a patient with a currently active type and screen, we have been collecting a new sample and reconfirming the type before using it for crossmatching. First, does anyone else do this? Second, does this note preclude that practice?

How does this make sense?

Thanks for any clarification you can give!

[Mabel Adams]

Do you allow this over the whole 3 day life (or whatever) of the specimen, and if so, do you still keep the original expiration of the sample?

[adiescast]

We allow it over the entire three days and the expiration of the sample does not change from the original sample expiration.

[Jane]

This seems as though it would rule out what you've been doing. Usually if we have a situation where we have no more sample, we would just tell the floor they need to order a new crossmatch and start over.

[Mabel Adams]

We sometimes collect more sample for problem antibodies but conserve the original that had the screen done on it for all crossmatches. Maybe you would want to consider getting bigger tubes drawn initially.

[adiescast]

There are a couple of problems with asking for more sample in the first round. The biggest is that we are supposed to be limiting sample draw to help prevent iatrogenic anemia. The other is that you don't always know who is going to go through the sample quickly.

I am actually not talking about patients with antibodies necessarily, because we also try to conserve some of the original sample for crossmatching (and we essentially end up screening the subsequent sample as part of the ongoing antibody identification process). I am thinking about patients who use a large amount of blood over their 3 day sample time (but don't fall into massive transfusion policy, which would allow no crossmatch) or whose original sample was lower than normal volume.

[John C. Staley]

Sounds to me like you are working up a justification to move to electronic crossmatching then sample volume would not be an issue.

If I run out of sample I get more, completely retest and move along. I don't see the problem. You test a new sample and the 3 day clock gets restarted. Considering all this patient is going through another 4 - 7 ml tube of blood should not be an issue.

[Karen Olsen]

If you do this a lot, I would agree with John!

If we run out of sample on a patient within the three days, our P&P states to collect additional sample, leave the outdate the same as the original sample and perform a T&S on the new sample and go from there. To avoid all of this trouble I would guess that most of the techs would just have the patient restuck with a new I-Denta-Band and treat it like a brand new specimen. Thus extending things for another 3 day period!

[rcurrie]

When we run out of sample for crossmatching on a patient with a currently active type and screen, we have been collecting a new sample and reconfirming the type before using it for crossmatching. First, does anyone else do this? Second, does this note preclude that practice?

There is nothing wrong with what you are doing as long as you perform an antibody screen on the new sample as well. The reasoning is that an antibody that was undetectable when you tested the first sample could suddenly become detectable on a new sample. You should perform an antibody screen on any sample you use for compatibility testing to cover this possibility. That is the intent of the CAP checklist question. Can it happen? You bet! Just last month it happened to us with a patient who had an undetectable anti-Jka (transfused at another facility) that suddenly became detectable after one transfusion with antigen positive blood. Time lapse: less than 24 hours between sample one and sample two. Yes, she had a hemolytic transfusion reaction, but she survived because we tested the second sample before crossmatching another unit. That second unit most likely would have done her in. Yes, it was pure luck that we needed a second sample, but that rare coincidence is what CAP is trying to CAPture ;-)

BC

BC

[adiescast]

Thanks for all the replies. Apparently we are out of line! Another procedure to revise...