Mabel Adams

Larry, is there another Meditech ISBT group that I don't know about or are you referring to our little email club? The big issues for Meditech users in ISBT are about aliquots and modifying aliquots (like irradiating them). Also, every possible source (collecting facility) whose units you might get must be entered in your source dictionary. If your supplier doesn't import much, you are lucky. There are many many functions that they now need to change to dealing with product groups instead of product codes, but they haven't yet.

How did the baby have enough maternal anti-A,B to react with the transfused cells, but not have ABO HDFN?

I don't think there is a real standard, just the arbitrary times passed down from old lab people to younger ones that seem to provide reasonable answers in a reasonable time. I read an article once that if you wanted the patient's blood volume to totally adjust after transfusion, you would wait 24 hours--assuming they didn't have heart or kidney problems etc. That is not going to provide timely enough information for medical care, so we accept a somewhat less accurate result. Most places use something between 30 min and an hour minimum I think. It still has to be interpreted based on whether the blood was given with lots of fluids or none, plus patient's other conditions.

Another quirk of ISBT is that some pheresis plasma units that are divided by the supplier because they are big enough to make 2 products will come labeled as divided units (with A0 or B0 on the product code). Compare this to the pheresis plts that have separate product codes for each of the expected divisions from one pheresis donation. I don't dare ask why. It meant that our system (Meditech) had to be able to scan in divided products and maintain the division information even though we won't be making any aliquits ourselves.

And what antibody caused the HDFN?

They make dial and electronic thermometers on metal "spikes" that would have no risk of breaking.

Pat, could you explain Dedicated units as well? Thanks.

If you only pick up an anti-M at room temp, then it isn't clinically significant and a gel xm is fine. If you do pick it up in gel, and it is strong at immed. spin, I sometimes do an immediate spin xm using the patient's sample to tell me which units to take through gel xms. Basically using the patient's sample to antigen type the units. We don't keep commercial anti-M since it is never necessary to antigen type units for it per Issitt.

Seems logical.

I remember being told that the entire fetal blood volume would not exceed the 30 mls covered by one dose of RHIG until after 20 weeks gestation. However, since then I have heard of cases with chronic fetal-maternal bleeds where maybe more than that could (rarely) accumulate over time as the baby makes more red cells. That would probably mean a FMH could conceivably be that big earlier than 20 weeks. Of course twin pregnancies would change the value too.

Is there any data on the effectiveness of two people doing the ID? I seem to remember reading once that it didn't improve much because each person figured the other one was paying attention and taking responsibility. Like everything, I suppose it is in the details: understanding of the need, training, adherence to the intent of the policy and reduction of factors increasing the odds of human error (fatigue, distraction). Get those right and any policy will work better.

Because the package insert says you should. However, I recall a lengthy debate on the AABB forums several years ago which revealed that many of us can't achieve a time-frame much better than 24 hours. Considering the rarity of RhIG failure, I doubt if we are causing much of a problem for our patients if it takes a few extra hours. Here's my logic for why it doesn't really matter so much: The claim is that ABO incompatible fetal cells will be removed from the mother's circulation fairly quickly so we need to collect a sample before those fetal cells are removed or we won't get an accurate count of the amount of fetal bleed. In the days before RhIG, it was observed that Rh neg moms whose babies were ABO incompatible with them were less likely to become sensitized to D. The theory I heard was that the ABO incompatible cells were removed by intravascular hemolysis so were never presented to the immune system like ABO compatible fetal cells would be when they are removed by the spleen. Seems to me the fetal cells the rosette testing package inserts are so worried about us detecting are not likely to cause sensitization anyway. Someone feel free to correct me if I am wrong.

Can someone explain how prozone would interfere with a direct coombs? It seems like the Fc portion of the antibody attached to the cells would still be available for the anti-IgG to attach to even if all the antigen sites on the red cell were full due to the high titer of the antibody. Also, I have read and done some small studies myself that most non-O babies of O moms have mom's ABO antibodies in their plasma/serum and on their red cells even if they have no symptoms of HDN and have a negative DAT. John Judd said that looking for the ABO antibody in cord blood was really only diagnostic if the expected one was missing. Then you needed to look elsewhere for the cause. If you find ABO antibodies in the cord blood, you don't know for sure whether it is the cause or an innocent bystander.

Happy New Year Yanxia!

http://en.wikipedia.org/wiki/Human_blood_group_systems might help.

I hope to revise our protocol soon to better capture symptoms of TRALI. We will have an ongoing need to educate docs, nurses and lab folks also. The only suspected cases we have had, the doc did not see any reason to report it to the BB although he told the family! Fortunately, they didn't really fit TRALI, but still...

We attach the IT card from Meditech to the unit and only occasionally hear of a nurse taking it off. We have been on MT about a year and had a removable transfusion slip (along with a manually completed Hollister label) on the units before that which we no longer have. Maybe you need some bright stickers on the IT card that say "tag must remaiin attached to unit throughout transfusion!" After a few years maybe you wouldn't need them anymore. Also, maybe there is a reason they remove it. Does it look like it has spaces for them to fill out? Is it in their way? Do you have traveling nurses that do it mostly? Time for "root cause analysis" to the rescue!

Well, John, that explains a lot. I didn't realize there was an automated survey. Thanks.

I won't really try to change your mind because I think a second specimen is better too. However, the statistics on mistransfusion show that errors in the BB are not a miniscule percentage. Maybe a 20% increment of improvement is worth something--especially when retyping the sample is so easy. Of course, at our facility, we wouldn't have the luxury of a second tech to do it most of the time. Getting that second specimen introduces some big issues for us--especially since one of our hospitals is a 15 min. drive away.

I wonder if there have been any studies done, or if these policies are just what made someone feel better about it.

I wonder if leuko-reduction before irradiation might make irradiation more effective since there are fewer wbcs present to zap. Hmm. Might be irrelevant, but just curious. Didn't they try leukoreduction in Japan and had to go to irradiation of all units because they have such a genetically homogenous society some patients that were not immunosuppressed were getting GVHD from unrelated donors?

We used to scan units into the computer for testing, but since we switched to Meditech, we don't do it this way. As you know Meditech isn't user-friendly for antigen typing. We have a paper log. We put a barcode unit sticker on the log. I made a laminated template to go over the log with see-through and/or open spaces for the current line to keep our eyes on the right line. We can then scan the unit number right through the template into Unit Edit to add the ag typing. Then we mark through the template onto the log to document that we have entered that one and move down to the next line. It is not foolproof. We could put the wrong sticker on the log initially or crossmatch the wrong unit. In the latter case, Meditech should flag that the unit isn't antigen typed so the tech should know to double-check. The only problem is that Meditech is known for tossing up messages when you don't expect them so the techs don't always trust it to be right. I would be interested in any solutions for places that only have one tech and an MLT on at night & almost never more than one tech in BB. Rechecks by second techs are pretty tough in that circumstance. Sometimes they assume that the original must be right and don't check very hard or the first person assumes that the second will catch any mistakes. I think a good deal of fear about antigen typing is a healthy thing.

If you look at the CAP survey results where they report the method used, you see vastly more gel users than solid phase. It will be interesting to see if the levels change due to introduction of the Echo.

We don't use the word Kalium that I know of here. Is that Potassium, (chemical symbol is K)? I see that wikipedia says that Kalium is the Latin word for Potassium--that must be where the K came from in the symbol. Another educational moment!

Our OB dept. was getting annoyed with the delay of identifying the anti-D in pos postnatal screens. Plus it was more costly. Besides the same action was going to be taken (give RhIG) regardless of the result fo the screen. If some other antibody was going to be found, the baby would probably have a pos DAT causing a workup that ID'd it. If not, the mom probably wasn't going to decide about getting pregnant again, based on the fact that she has an anti-K. It would be dealt with in the next pregnancy, if there is one.