exlimey

I think we're confusing ourselves. I was referring to the original post which suggested a modification of procedure in order to enhance rouleaux/colds. Serological assays are typically read "without undue delay", i.e., immediately. If some techs have a practice to "let tubes sit before looking at them", that could be construed as deviating from the procedure, unless they have some bizarre and very specific local instruction to do so.

If the patient is being treated/transfused in a high level hospital with staff who understand Malcolm's explanation (above), then I would probably not recommend using O cells. However, I suspect that in many smaller hospitals it would be simpler from both administrative and technical understanding points of view to give O cells. This approach may not be ideal if the patient is a chronic or large volume user of red cells (those group O cells are a little more precious and useful in emergencies), and the laboratory now has to deal with an even bigger mixed field scenario. My experience with loss of ABO antigens is similar to Malcolm's description, but I never had the cool ability to track the patients' health.

I don't understand this statement.

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I echo the above sentiments - why go out of your way to "catch rouleaux and cold" which are just "a nuisance" ? It's a "waste [of] reagents and expensive technician's time." From a technical/regulatory point of view......if you do want to detect rouleaux and/or cold-reactive antibodies, use an assay/test designed to do so. I don't think the various regulatory bodies would appreciate what you're doing - a deliberate deviation from an existing test protocol or SOP.

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First step is to determine what are you trying to prove. Do you want staff to merely have a productive/reactive eluate, or do you need them to identify the specificity, too? As Malcolm says, if you're in a blood center/centre, with access to whole units of plasma containing IgG antibodies of various specificities, it can be relatively easy to sensitize red cells with the appropriate phenotype (from your RBC inventory). Using D+ cells with anti-D is the simplest approach (or use Check Cells). This would certainly satisfy the mandate for a productive/reactive results. But, if you want the added challenge of antibody ID, using the same cocktail of reactants each time will lessen said challenge (as Cliff commented). But, back to basics.....make sure you have a specificity which is IgG in nature, reactive only by IAT. It should be relative strong WITHOUT LISS or PEG enhancement - use the standard/original saline-IAT to chose your antibody source. Always incubate your sensitization phase at 37C. You may need to vary the ratios of packed cells to serum to get optimal results (typically at least 2 volumes of antibody to one volume of packed cells). The shelf life of the sensitized cells may be increased by suspension in a red cell storage solution/preservative.

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I was taught, many, many moons ago, that prewarming should only be applied when the identity/specificity of the antibody is known/understood, i.e., you know what you're trying to avoid. Cold autos are probably the most commonly seen, but "nuisance" cold-reactive antibodies like anti-M, anti-P1, anti-Lea/Leb can also pop up and potentially be avoided using a prewarm version of an assay. These specificities are usually IgM class, are amenable to prewarming, and are generally considered clinically insignificant. Prewarming to "get around them" is often a good option. However, a cautionary note: There are cold-reactive antibodies that can present in a similar fashion that are clinically important - anti-Vel , anti-PP1Pk, for example. It can be dangerous to use prewarming to avoid these sometimes potent and potentially life-threatening alloantibodies. Prewarming may be a very useful tool, but as is true for very specialized tools, it should only be used and applied by trained and experienced operators who understand its strengths and weaknesses.

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Not she, but it's possible the person that conveyed it to me got it from Dr. Worlledge.

Something one of my mentors said early in my career: "Don't worry about junk. If it's a real antibody and you transfuse against it, it'll be nice and strong by the next time you see the patient."

Your comments are spot-on, Malcolm. A "reference range" is typically the expected result from normal individuals. This is fine for something like a platelet count or a creatinine quantitation (or any of the chemistries), but is absolute nonsense for an assay that has only two potential outcomes: Positive or Negative. I suppose "Indeterminant" might be a third option. Here's your Reference Range for Antibody Screens: Positive / Negative / Indeterminant

Concur with the above. It would have be a very serious F-M bleed to impact phenotyping. While there is a theoretical risk of mixed field, and potentially spurious interpretation of the results, if a gravid patient develops an antibody that late in the gestation, the very small risk of mistyping/reporting is worth taking.

Is this approach applied to rare units ? For example, a donor who is Kp(b-), with anti-Kpb in their circulation. Granted, such a unit would probably only go to someone who already had anti-Kpb, so technically there would be no impact (analogous to Mabel's anti-D scenario). Just curious.

It's remotely possible that Ortho use different diluents for different cells. I remember a rumor that "fresh" cells are suspended in one kind of diluent, but frozen-thawed cells are in a similar diluent with a couple of extra chemicals to compensate for the freeze-thaw process. I think that frozen-thawed (deglycerolized) cells are sometimes used in emergencies when the scheduled donor(s) don't appear.

I agree with all the previous comments. You cannot manage a transfusion reaction in a patient who has died from lack of blood. One thing to add: In the time before time......emergency release units were always O negs. However, today's practice has evolved in a risk-based manner and it is now accepted that O pos units can fulfil this function. Perhaps ironically, if the old practice had been employed in this case (use O negs), it would have been very unlikely that this patient would get a E+ unit.