exlimey
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Everything posted by exlimey
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Apologies in advance to the above for using their comments as examples. Just to stir-up a little controversy.......if we trust our Government-regulated/approved blood suppliers to have quality systems, get the correct answer and label accurately, why are in-coming Red Cell Units re-typed for ABO/Rh ? And....go......
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I believe the primary action of CDP is as a mild acid, thereby eluting bound IgG (reducing DAT) and denaturation of HLA/Bg antigens (removal of "unexpected reactivity"). Perhaps the prolonged treatment time removed some of the sialic acid on the red cells and has inadvertently created cells that are easier to agglutinate, i.e., the equivalent of enzyme-treatment ?
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Lots of users on this Forum are in the same place and I'm sure they have some good advice on how to approach this issue. However, I would be cautious of implementing an optional process that potentially calls into question the quality of previous work.
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"Pettifogging".....an 'olde worde" that is so relevant today. Thank you for reminding me. I shall try to work it into as many conversations as possible.
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Agreed....history is always a wildcard. I had a case once where there a teenaged male individual had antibodies to red cells (I can't remember the specificity) with no apparent transfusion history. Later questioning revealed that the person was part of a "Blood Brothers" group who routinely and ritually exchanged blood through self-inflicted cuts. Each to their own.
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I was also thinking of a prior sensitization. A weird, barely detectable D+ phenotype may not generate a new immune response, but may be enough to reactivate the primed lymphocytes in an individual who's anti-D has faded into non-detectability. Tiny re-exposure and wham ! Nice, strong, clear-cut anti-D, apparently out of nowhere.
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Reading between the lines, I believe you're saying that C+D- (r'r) panel cells are nonreactive, thereby excluding the presence of anti-C, If that's the case, and since said cells should carry the G antigen, it is very unlikely you're dealing with anti-G. Anti-LW may mimic an anti-D pattern by demonstrating reactivity only with D+ cells. It's also very remotely possible that one of the donors carries a rare form of D-antigen that is not readily detected by typical commercial reagents. However, those are very rare and their ability to stimulate an immune response is not well understood.
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In this case, the Safety goons may be your very best friends. If the space you describe is really that bad, you could use the safety angle as leverage. Alternatively, modern instrumentation (including the Ortho Vision) often has very specific installation requirements (space/clearance/ventilation, etc)....that may ammunition, too.
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Careful, now. You're bordering on "spatial discrimination".
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Recovering Anti-D from an eluate of an RH negative patient
exlimey replied to mimi03's topic in Transfusion Services
How about a "Del" ? Fits the description perfectly. One the other hand, "twice in the last few days" is worrying. While not impossible, it's highly unlikely that a facility would encounter more than one of these anomalies (zebras) in such a short period. I assume Malcolm's question regarding the Last Wash is an allusion to some laboratory artifact - bad technique, bad reagents, etc. -
Do you antigen type for the entire group?
exlimey replied to rmilford's topic in Transfusion Services
Understood. There are many things laboratories do because they've "always done it". Those in the decision-making roles probably saw a "bad case" somewhere along the way and it stuck in their brains. I will concede that there are a smattering of cases of Lewis antibody-mediated transfusion issues to reference, but most workers consider them an insignificant nuisance. -
Do you antigen type for the entire group?
exlimey replied to rmilford's topic in Transfusion Services
It's highly unusual, to put it mildly, to worry about antibodies to Lewis antigens. What's your institution's logic for this approach ? -
Excellent point, Ensis01.
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An interesting case/issue. I agree with your premise: doing anything to make the saline control nonreactive (warm-washing, CDP, acid-elution) will probably make the test with anti-IgG negative, too (assuming the positive saline control is due to IgM-coating of the patient cells, causing direct agglutination). Perhaps a DAT with an anti-IgM reagent could be arranged ? Did you try a DAT with polyspecific antiglobulin reagent or a monospecific anti-Complement reagent ? But even results from these could be "invalidated" by reactions in the so-called negative control.
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Excellent use of your "abundant spare time" ! On a more serious note, analysis of this kind of data could lead to modifications in typical practice and result in efficiencies of time and money (and, ultimately, patient care/outcome). However, if the ultra-bean counters get hold of this issue, there's a very good chance that they will find, and put administrative restrictions on all kinds of "unnecessary testing". I appreciate that medicine evolves, but sometimes the appropriate approach has already been identified.
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This is a very interesting question. I suspect that many, many, many tests requested by the ED (A & E) could be categorized as "unnecessary" during analysis in the quiet time after "The Storm", i.e., the results had no relevance to the patients' treatment. But, in the moment (especially, during trauma), the medics have very little idea of what clinical data is important at that time. A "shotgun" approach seems to be appropriate. I'm not sure there is a way to meter or control this process (other than having extremely savvy ED staff). It seems to be a necessary evil - the need for rapid turn around overweighs the concern of "over-ordering" tests. And, as Malcolm says, a little extra time for the BB to do its work is always appreciated.
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That made me think. I must have done many hundreds of elutions and have never seen reactivity in the last wash. Perhaps I was just lucky. I assume someone on this Forum has encountered reactivity in the last wash. Anyone care to share their experience(s) ? What were the circumstances ? What was the patient's diagnosis ? How did you resolve the issue ?
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Our machine is a combo color printer/photocopier/scanner. Just like most "multi-tools", it's OK, but doesn't really do all of its tasks exceptionally well. Grey shading often comes out bluish and when it scans colored materials, the colors are badly translated. Ho-hum, First World problems.
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I agree. I like the blue ink option because it used to be an obvious indication that the document is the original. Now, with color photocopiers in widespread use, I have to double check. Sneaky !
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Was the Antibody Screen also performed in "the tube" ?
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Very interesting. May I ask what assay/test is being used to detect the antibody ? Tube (with or without additive), gel, solid phase ? And, may I presume that the anti-P1 is believed to be the the cause of "the hemoglobin has been dropping even with transfusion." ?
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Interesting discussion. Yes, cardboard can carry dirt and/or insects, but to imply that the presence of such on supplies like saline cubes creates a risk to patients and staff is an extreme stretch. We don't live in a vacuum and most of us spend time outdoors with the dirt and bugs every day (potentially bringing them inside with us). A wipe with a damp paper towel should be sufficient to clean an obviously soiled outer container. If you talk to the manufacturer of the saline, I'm sure they would argue that the outer box is not merely a convenient shipping container, but also an integral part of the product itself, designed to support the flexible primary container and get the best performance from the product. After all, they've designed in a nice little tear-out section that creates a perfect hole for the spigot/tap.
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But, but, but....you said "We QC the reagents". The equipment/instruments are qualified and deemed functional through calibration/certification/validation, and presumably, preventative maintenance.
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Thank you, David. As I suspected. So why do two test systems using the same lot numbers of reagents need to be subjected to daily QC ? Let the debate begin.....
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Very interesting, Sandra. I completely understand the intent of the regulations and I appreciate that first impressions of cleanliness of blood products are important. However, it appears that in an arguably overzealous attempt to keep everything "clean", the fact that the outside of any blood bag is not sterile is completely overlooked. The air to which the exterior of blood products are exposed (refrigerated or room temperature) is not sterile. But....this is not relevant because the product inside the bag is supposed to be sterile and appropriate precautions are used during infusion events. That being said, I like a clean, orderly and well-labeled refrigerator !
