jhodam

Whoah, Mr. Needs, apparently I was misinterpreted. I wasn't trying to sound like a jerk or anything. I've been spoiled to have the Southern California Region American Red Cross reference lab local, so I'm not accustomed to reference samples being turned away. Sometimes I need to be reminded that such a resource doesn't exist for everyone, and I thank you for bringing that to my attention. I guess I was trying to remain open in my mind as to what could be going on with an incompatibility detected after seeing a patient specimen for the fifth time. 1/10 units (assuming 2 units per transfusion "event") incompatible is a little different than 1/1000. I'm not sure what your threshold for "low incidence" is, but I was thinking a little lower than 10%. But yes, I assumed a lot and didn't qualify that, so for that I apologize. It's always intimidating taking that first step into a public forum, especially when one might not express themselves as well as they'd like. It's in writing, so I guess I don't really have an excuse. As for my lack of social graces to begin with, I blame my mother and society. I often find myself paying for my sense of humor (or, as you would probably argue, complete lack thereof). In the future (if I haven't at this point been thoroughly discouraged from further contributing), I'll make sure to read each post at least three times over to keep from posting anything that might be misconstrued as offensive.

I second Malcolm. Next to the AABB Technical Manual, Dr. Reid's and Ms. Lomas-Francis' book is the reference I use most often. I noticed Amazon offers The Blood Group Antigen Facts Book in Kindle format. Has anyone used the Kindle edition, and if so any opinions? I have the Kindle App on my iPhone, and if I could carry this reference everywhere I went in my front pocket it would just make my decade. Jason

What's the process, just out of curiosity? Something that might be stored longer than 4 hours? If it's for pooling cryo or adjusting crits for intrauterine transfusions or something like that, try checking with your own nursing or hospital supply (assuming you're in a hospital). Back when I worked for a facility that pooled their own cryo, that's who supplied us. If they're too stingy to kick you down a bag of saline every now and then, they should be willing to tell you who they order it from and the name of their rep.

Like Malcolm said, I would think it more worthwile to test the patient for c antigen first, since most people will be c positive. I guess the line of thinking is that c and E are equally immunogenic, and if a patient has formed anti-E they are certainly capable of forming anti-c. Since a transfusion recipient is very likely to encounter c antigen, you would want to limit his or her exposure if it's already been shown they are likely to develop the antibody.

Your reference lab told you not to send them something because it was low frequency? What's the point of them being a reference lab, then, if not to figure that kind of stuff out? Who is your reference lab, so I know who not to look at the next time I'm going through a job search? Did you do an AHG crossmatch on the incompatible unit? You mentioned you did an IS crossmatch but no extended workup. If it doesn't react at AHG I would feel better myself about the "low frequency, probably clinically insignificant" label. I wouldn't place too much significance on the cold panel, just because you're seeing positives everywhere doesn't mean that's specific to what's going on with the incompatible crossmatch. Cold reactive "antibodies" are pretty common. I would find a different reference lab. Even if it is clinically insignificant as it probably is, it's always better for the sake of being thorough (and peace of mind) to nail down a specificity.

The rosette test is a screening test. That's why it's called the fetalSCREEN from Immucor. The confirmatory test is a Kleihauer stain or flow cytometry. If you're going to get false anything from your screening test I'd hope it would be a false posive. The rosette test is quicker and easier than a K-B or flow, that's probably why it's remained in use despite the false positive problem, which I'd estimate at around 15-20% at my facility (~20% of positive FetalScreens come back below 0.3% fetal cells with KB stain). I'm not sure how that works out overall, but obviously far less than the 66% Sandra quoted as discrepant among responders on the CAP survey. It seems more likely to me the specimen was to blame than the kit, we're not all getting 66% positive FetalScreen results.

Just for discussions sake, would anti-A1 in this unit, if clinically significant, be of more concern than IgG anti-A1 in an O unit of red cells? Or for that matter a unit of O platelets going to an A or B recipient? We check for high titer anti-A and B in platelets and transfuse O's to A's if below 1:200, do other institutions with a similar policy look into immunoglobulin class as well before serologic mismatches are transfused? Thanks, Jason

Hello, We have a regular donor that is a subgroup of A, most likely Ax or A3. Their red cells fail to react with reagent Anti-A or Anti-A,B. The donor also has anti-A1 that reacts 3+ in the reverse type, so taken together reactions are consistent with a type O donor. The only reason we know the units type is that our local community blood bank tags it with a “heads up†card (as they like to call it). Since we are unable to confirm the type of the donor when we receive the unit from the collection facility, I am wondering if we are out of compliance with the requirement for confirmatory testing of donor blood? Or is the report from the reference typing lab good enough with Medical Director approval? I am also curious about how this might have been discovered in the first place with this donor, as he/she types straight up O pos. I can coax the forward type out with Anti-A,B in the fridge for 10 minutes, but it’s barely macroscopic, and such a procedure wouldn’t be standard practice for the reference lab doing the typing the first time this donor was tested. They do their types on a Galileo, the same as we run ours on, so I know they aren’t using a different method or different reagent. What are the chances a donor like this could be missed in general and have their blood end up in a O patient? Thanks in advance, Jason

Hi Antrita, I'll take a stab at your little d question. It's my first post, so don't rip me too hard. Rh-negative folks still have an Rh protein (unless they're the Rh-null phenotype), it's just that their RhD allele is not immunogenic. An antigen is something immunogenic, that your body can make an antibody to. Just because your immune system doesn't make an antibody to the protein doesn't mean there's nothing there, and just because someone is Rh-negative doesn't mean they lack the protein that the antigen is a part of. I don't know if that makes any sense. Basically, Rh-positive folks have a form of the protein that is the Rh "substance" that people can form antibodies to. Rh-negative folks have the protein, too, but theirs is a little different due to mutation and the immune system doesn't recognize it as foreign and form the anti-D antibody to it. It's still a functional "Rh protein", it just won't form antibodies. I think a lot of times people forget that the primary role of red cell antigens isn't to be an immune system target, their parent proteins (or carbohydrates, or whatever) do have roles. The Rh protein is a structural protein, the Kidd protein is a urea transporter, Duffy is a chemokine receptor, etc. Take it easy, Jason