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Posts posted by exlimey
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29 minutes ago, Malcolm Needs said:
If a mixed-field reaction is seen, I would worry more about the health of the foetus than I would about the maternal typing, as, for a mixed-field to be seen, either the foetus has had a massive bleed, or has had a chronic bleed over a long period of the pregnancy.
Very good point. One could argue that ALL pregnant women should be phenotyped specifically to look for mixed fields.
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10 hours ago, yan xia said:
I think this phenomenon is because the B antigens are not well developed on new born baby. BTW, I prefer to use 3+mf to describe it
The reason I don't use 4+mf because 4+ agglutination is a kind of solid agglutination, without free cells .maybe I was wrong, just personal opinion.
2 hours ago, Malcolm Needs said:I totally agree with yan xia about the cause of the mixed-field.
A, B and H antigens are not direct gene products (they can't be, as the antigen is a sugar molecule attached to a polysaccharide molecule), whereas the D antigen is a protein, and so is a direct gene product (give or take a few post-translational changes).
The gene products of the ABO and H genes are transferase enzymes (alpha-1-3-(or alpha-1-4)N-acetyl-D-galactosyltransferase for the A antigen, alpha-1-3- (or alpha-1-4)N-galactosyltransferase for the B antigen, and L-fucosyltransferase for the H antigen), and these enzymes are not working at their optimum at birth, and so it is not unusual to see mixed-field in the samples of newborns, particularly if they are premature.
As the Rh antigens are direct gene products, i.e. proteins, mixed-field reactions are birth are very rare indeed, and usually there for a completely different reason.
Concur.
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On 10/6/2017 at 2:09 PM, lab217 said:
Do any Blood Banks allow phenotyping of pregnant patients? Is there a timeframe defined during a pregnancy that accepts this practice? Some Laboratories phenotype and accept only negatives or strong positive reactions as conclusive.
What does your blood bank do?
I'm assuming....yes, that gets me into trouble all the time......that you're worried about antigen suppression in pregnant women?
Antisera licensed in the USA should have been tested extensively with samples from such patients. If they were unable to correctly phenotype samples from pregnant women, it's unlikely that they would have been approved. As Malcolm points out, the only real troublemakers are the Lewis antigens.
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10 minutes ago, Baby Banker said:
I remember that too, but this was a gas I think. It left a residue in the disposables that caused some patients to go into anaphylactic shock. It was in the Technical Manual a few versions back.
Eek ! I don't like the sound of that.
Ethylene oxide (ETO) is a gas used to sterilize materials that can't tolerate other processes (heat/radiation).
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I'm certainly not a regulatory expert, but if it is indeed a requirement, I would think that a general "other antigen typing" proficiency would cover you. I can't imagine why one would need proficiency testing for one, or each, typing antiserum.
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1 hour ago, Baby Banker said:
I vaguely remember hearing that patients may react to the chemical used to sterilize plastics. I think it's a bigger problem with patients on dialysis.
That was the formaldehyde solution that was used to sterilize reusable dialysis machines in situ. The patients would often make an anti-N-like antibody ("N") that could cause trouble in the AbScr and XM. In the old days, dialysis patients used a LOT of blood. Now, with EPO, they hardly use any.
Technically, they didn't have an allergy to the plastics/materials, but rather, as you pointed out, the sterilizing agent. However, it would not surprise me if some patients do develop allergies to today's materials. It seems that everyone is allergic to everything, these days.
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Just wondering......several contributors have used the term "direct observation".
What would be involved in "indirect observation" ?? Mirrors ? Peripheral vision ? CCTV ?
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1 hour ago, Carrie Easley said:
Paperwork/double-check rule-outs.
Fair enough. I thought you meant actual duplicate testing.
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53 minutes ago, Carrie Easley said:
Once a year for each method, but we require a second tech double-check of all ABID's prior to blood issue.
Is that a paperwork/clerical check or do you actually test the samples twice?
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1 hour ago, John C. Staley said:
My favorite transfusion reaction work up resulted in closing the blinds on the window to keep the sun from beating down on the patient resulting in a rise in temp. True story.
And remember when the "blood warmer" was a few minutes on the radiator/heating vent ? Good times.
- John C. Staley, MOBB, Malcolm Needs and 1 other
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11 hours ago, DPruden said:
I was overthinking. Thanks for the feedback!
I believe we're all a little guilty of that misdemeanor. It's always good to keep thinking and this forum is an excellent place to throw ideas around. Unfortunately, it is easy to get lost in the matrix when "we" start to second-guess and try to predict the next thing the Regulators are going to pursue. Often, it's a case of trying to fix a problem that doesn't exist (yet).
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Think over the premise again. What is the purpose of the CAP program (or any other proficiency) ?
Are you testing your facility's ability to get the correct answer (proficiency) or are you qualifying the instruments ?
I would argue that it more important to "test" the operators rather than the instruments and therefore the actual instrument used is irrelevant.
As a sideline.....what would happen if you got different answers with different instruments? That would be a real pickle.
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On 9/22/2017 at 2:26 PM, Jennifer Castle said:
We run the panel with diluted anti-sera (Currently Anti-Fya at 1:500 dilution). I am assuming that you are testing the cell viability, and that the panel will perform as expected. We test before the old lot expires.
Please explain how a negative result with (diluted) anti-Fya determines "cell viability".
"We test before the old lot expires" - this means you qualify the new panel before putting it into use ?
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46 minutes ago, Malcolm Needs said:
On the other hand, in an acute situation, if the screen is positive, you are wasting time doing the screen, because you will then have to go on and do the panel while the patient is still bleeding.
A fair point, Malcolm.
So, I once again pose the rhetorical question: In an acute situation, do you do a "Type & Screen" or a "Type & Panel" ????
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55 minutes ago, jmm8427 said:
One could argue that by doing the panel first you are being efficient and potentially saving time with antibody identification if something is detected. But by doing the screen you are saving reagent/cost. I'm not sure there is a right or wrong answer to this question?
Rhetorical question: Is it a typical request for a "Type & Panel" ?
If you are almost certain that the eluate will be reactive, I agree that the screen may be redundant. However, it is still a test against phenoptyped cells and the information is still valuable even if you end up testing a panel.
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Preparation and standardization of enzymes is notoriously VERY difficult (making trypsin is a nightmare). Each batch of source material may have a very different activity level than the previous. Stability is also an issue, even when frozen.
You can probably get all of the enzymes you list from Sigma, but they will undoubtedly have 15 versions of each and it may be difficult to choose which flavor is most suitable.
I would stick with papain and DTT. They'll be most useful, most often. You'll get a lot of information from just those two. Only the very highest-level Reference Labs. should mess with alpha-chymotrypsin, trypsin and pronase.
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A good serologist is an efficient serologist. Do the small work first - the screen. Only do the panel if the screen is reactive and you need more information.
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9 minutes ago, Malcolm Needs said:
I may be wrong, but would not such anti-A be adsorbed onto the patient's own red cells, and, considering that ABO antigens are histo-antigens, onto the patient's tissue cells?
Very true and quite possible, especially neutralization by serum antigens. One might even see a positive DAT if the patient's cells sucked-up passive anti-A. On the other hand, a large enough dose of out-of-group platelets might leave some isogglutinins available to mess up the ABO results. Just throwing out ideas.
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Passive anti-A from a transfusion ? Possibly from a platelet product ?
I agree with testing more group A cells.
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This is obviously still a ticklish issue. Several good arguments are presented above, but a couple of things come to mind....
A mis-draw is always a possibility, but some of the algorithms above suggest that it happens on a regular basis. Does anyone here have statistics ? I'd love to see what the data says.
Even when drawing a second specimen, based on blood group frequencies, the odds are very favorable that you'll get a corroborative ABO/Rh typing, EVEN IF THE SAMPLE IS COLLECTED FROM A COMPLETELY RANDOM PERSON.
Just a couple of thoughts.....
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13 hours ago, TreeMoss said:
We crosscheck the antibody panels when they are received against the panel currently in use using diluted anti-D reagent to give 1+ reactions.
How does that process "qualify" the Rh- cells ?
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On 8/19/2017 at 4:46 AM, rravkin@aol.com said:
A well qualified and dedicated managerial team is always needed as this factor can make a huge difference in meeting the obligations of resource management and service delivery, and staff maintenance, while maintaining fiscal responsibility. It is here that I have experienced the greatest shortage.
Even the very best of managers or management teams cannot work miracles if they lack the appropriate resources.
- ANORRIS and Carrie Easley
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45 minutes ago, SMILLER said:
Whether you call yourselves Lean (or Six Sigma or some other facetious productivity name) or not, the reality for many labs these days is that generalists are more and more necessary to keep things going in light of personnel shortages,
We are a 250 bed level 2 trauma hospital, with a fair amount of Lab work on the type of patient population we see, including BB. The only real "dedicated" techs we have are in Micro (and of course, Histology). About a quarter of the techs on first shift are generalists that can work on a regular basis in BB (in addition to the main Lab area). On second and third shift, virtually all of the techs work BB in addition to the main lab area.
Whether one has BB with all dedicated staff or no, the key is to have adequate training and competency, along with extensive references, including having good P&Ps available. This is true for all areas of the Lab (and in health care in general!). It requires a sharp and dedicated management model and staff.
Scott
Well said.
Pregnancy and phenotyping?
in Transfusion Services
Posted
Yeah, I know. I was just being silly, pointing out that sometimes what sounds like a reasonable idea is often impractical and mostly useless.
Proposed new policy: Type them once every week for the duration.