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On 3/17/2022 at 5:32 AM, knelson said:
We were told by the Ortho rep that trained our staff that you need to have an air gap between the patient plasma/reagent rbcs and the liquid on top of the gel in the column for the same reason described in Arno's post. Years ago we had a tech that always got weaker reactions with daily QC and we finally figured out that after she pipetted the rbcs and patient plasma into the gel columns, she would tap the card until the plasma/rbcs mixture touched the liquid layer in the column. Her reactions were always 1-2 grades weaker than everyone else. Once she stopped doing that, she got much stronger reactions. We use a Biohit pipettor and hold the pipettor at a slight angle and pipette towards the side of the well. This works well. Should the rbc/plasma mixture touch the liquid layer in the well, we discard that well and repipette using a new well.
Are you using the Biohit pipette in a manner that may compromise the accuracy of the volume delivered? Does the pipette instructions indicate that it is okay to use at a slight angle?As Elinf has mentioned, how do you explain automated gel card readers? Do they use the air gap method?
Thank you.
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4 hours ago, exlimey said:
From reading the previous comments, both old and new, it appears that the manufacturer (Ortho) does not specifically require the bubble and therefore nothing is in writing (the Directions for Use). You may be out of luck trying to find something to reference.
On a previous new post, someone said the Ortho Representative told him they needed to do the air gap method. If Ortho is requiring the method, it would be nice to have some printed material about it. If there is none, it’s no big deal, I think I’ll live.
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11 hours ago, exlimey said:
I find it interesting that various users have been told/advised to use a pipette in a manner that may compromise the accuracy of the volume delivered. I'm sure the pipette instructions indicate to use vertically.
Thankfully, the serological assays that are used by the Transfusion Medicine field have a wide range of tolerance. The "1-drop to 1-drop" concept is horrifying to many other pathology disciplines.
I have never seen the pipette used any other way than vertical. I was just looking for printed materials for this air gap method, if any exist, so I can have something official for my reference. Thank you 🙏
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On 3/17/2022 at 5:32 AM, knelson said:
We were told by the Ortho rep that trained our staff that you need to have an air gap between the patient plasma/reagent rbcs and the liquid on top of the gel in the column for the same reason described in Arno's post. Years ago we had a tech that always got weaker reactions with daily QC and we finally figured out that after she pipetted the rbcs and patient plasma into the gel columns, she would tap the card until the plasma/rbcs mixture touched the liquid layer in the column. Her reactions were always 1-2 grades weaker than everyone else. Once she stopped doing that, she got much stronger reactions. We use a Biohit pipettor and hold the pipettor at a slight angle and pipette towards the side of the well. This works well. Should the rbc/plasma mixture touch the liquid layer in the well, we discard that well and repipette using a new well.
Since a representative from Ortho says we need the “air gap”, does Ortho have actual printed material with instructions on how to do this air gap method?
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On 10/5/2006 at 1:20 PM, lef5501 said:
I was once told (or read) that when using the IgG gel cards, it is best to leave an air bubble between the serum and the gel layer. Supposedly this enhances the incubation of the reagent and the patient serum to better pick up weak antibodies. Has anyone else been told to do this or are they leaving an air pocket when testing antibody screens in gel? Sometimes it is very difficult to leave that air pocket when pipetting, just wondering what everyone else was doing.
I know this thread is really old. I was wondering if anyone else does this technique and what is your principle behind it.
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Welcome! You came to the right place! The members here are experts in BB and quite knowledgeable in the field. Good luck with your studies.
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It has been over 100 years since the ABO blood types have been discovered, but we still don't really know what are their "function"? What exactly do they do? What did they evolve from? Thank you
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6 hours ago, galvania said:
And a bit more 'way out' - has he received any plasma for Covid that might have contained the anti-D?
I doubt that would be likely, since I think a positive antibody screen disqualifies donors. But maybe I am wrong.
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On 10/1/2021 at 2:10 PM, carolyn swickard said:
What about RH pos plasma products or platelets? Though they don't tend to cause an anti-D, they can "spike" one that dropped below detectable levels, I believe. And that far back, if any platelet concentrates were given, they would have had more RBC exposure than they do now with platelet pheresis units. Just a thought.
In plasma products, what exactly would "spike" the formation of Anti-D? Residual D-positive RBCs or platelets?
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On 10/27/2015 at 9:02 AM, Dr. Pepper said:
OK, the only magic to the "3+3" rule is that if you plug those numbers into the horribly unwieldy formula for Fisher's exact method of calculating probability, you will get a probability (p) of 1/20, or a 1 in 20 chance that the reactions could have occured by chance, or a 95% confidence level that your conclusion is correct. (This is a totally arbitrary number by the way.) Lower p values (1/15, 1/9 etc) allow for too much chance of random association. Higher values (1/28, 1/56) show that there's a much smaller chance that your conclusion is incorrect.
But there are other magic combinations that will give you an acceptable p: 5 and 2 (1/21), 4 and 3 (1/35), 6 and 2 (1/28) and so on. You do not necessarily need 3+3. See Goodchild's reference.
You run into problems when you only have one positive or negative cell: 7 and 1 (p of 1/8), 8 and 1 (1/9), etc. You would have to get to 19 and 1 to get the magic p of 1/20. If you think about it non-arithmatically, what if your one reactive panel cell is also positive for an unlisted low frequency antigen? What if your one negative didn't have serum added or isn't reacting for some other technical reason?
So you don't necessarily need 3 Cw+ cells; 5 or more neg and 2 pos would suffice. And you don't need 3 Js(b-) cells; 19 pos and 1 neg would be OK statistically. The problem I see with the high incidence antigens like this would be that with only one negative cell with which to rule out, you would still have a bunch of other antibody choices you would like to rule out, hence the need to test more negative cells.
So, pedantry aside, the bottom line is "don't base your ID just on the reaction with one cell". A second cell of similar makeup coupled with the pos or negs from the rest of the panel should bump your p past 1/20.
You wouldn't happen to know the Fisher formula or where I can find it? I am just curious about the actual math/statistical tool(s) involved in the rule of 3. Thank you.
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On 8/20/2012 at 6:37 AM, yan xia said:
Auto-antibody is a very headache question worry me, if saline incubation can resolve it , I will be very happy.
I am very interesting in how to do it, and is it useful when the auto is 37 degree reactive and very strong. Thanks for your opinion.
Rarely you will find an WAA stronger than an underlying alloantibody. That is what makes this method useful. The weaker autoantibodies won’t react and only the stronger alloantibodies will react. Attached is the AABB sop for this method.
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On 8/5/2012 at 8:43 AM, labgirl153 said:
Well, that's mighty nice of you to suggest busy work for me RRavkin. My question relates to literature in the past half century. Surely, in the 67 years since its introduction, someone has made a comparison of the saline incubation technique to other methods. If not, then that speaks favorably toward tradition but is not so flattering toward the upper echelon in blood banking. Believe I'll take this SOP question up with the AABB folks and possibly CBBS. Hopefully I'll get a response directly pertaining to "papers" and "research". If not, then the answer will finally be clear.
I know this thread is several years old but I just want to say I agree with Malcom.
Also, i just want to add that I have been researching this method for the last few days, and found out that many labs use this method.
The main idea here is that alloantibodies usually have a stronger reaction that WAAs. So if you don’t use saline without any enhancements, you will only get the alloantibodies reacting. This especially works well when the underlying alloantibodies are 2+ or greater and the WAAs are 1+ when done with enhancement.
It’s a “quicker” way to identify alloantibodies without doing an autoadsorption.
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Thanks everyone for your input! I found the method on the AABB website. It's attached if anyone wants to see it. Thanks again!
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9 hours ago, BloodBankBlake said:
We use regular blood bank saline or whatever suspension the reagent RBCs are in (as long as it isn't a LISS suspension). The procedure is just doing a screen/panel/xm don't add enhancement media, and incubate for 30min@ 37C
This the tube method? Thanks so much ! How many tubes do you use for your panel ?
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38 minutes ago, BloodBankBlake said:
From my manager's "old school" approach that if a clinically significant antibody is present with a warm auto, it will react alone without enhancement media due to its supposed "high" titer. Similar to slsmith, we incorporate this approach when we have panagglutination in our more sensitive methodologies and are trying to "look through" these reactions. It's never our sole method or what we use to report, but just another arrow in the quiver of techniques.
Thank you for your response. What is the ingredient in this saline? Do you know the manufacturer name or the procedure steps? Thank you.
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1 hour ago, slsmith said:
We use it when working with a patient with a warm antibody that has had all significant antibodies ruled out by the reference lab. The gel screen is still performed each time to make sure reactions are not getting stronger or no longer demonstrating. Then the saline panel is performed. We also transfuse with phenotypical matched blood for Kell, C, E and c . This procedure is usually being performed on the frequent fliers that we know are only coming to our hospital.
We also use it when a gel shows no pattern, all cells positive or negative and we have gone to PEG and all cells are positive. The saline panel has to have at least 8 cells and ran with an auto control. If the panel is negative including the auto control it called a NSF and saline tech is use for the xm. IF the auto control is positive it is called a warm auto. If it is positive the work up is sent to the reference lab.
The principle behind this I can't explain it is just what we do.
Thank you for your post. I am sorry, but what is NSF? Do you know the name of the manufacturer of this saline panel? or know of any sources about saline IgG? Thank you for your time and help.
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Anyone here has any experience with saline IgG and it's use in detecting underlying alloantibodies? In a situation that may involve possible multiple alloantibodies or warm autoantibody(ies). I would like to find out more about the principle and the procedure behind this. Thank you.
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11 hours ago, Malcolm Needs said:
Hope this helps.
Yes, it is very helpful! Thank you Malcolm.
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Thank you Malcolm. Would you have any sources/web sites on this subject? I would like to read more on the subject if possible. I tried googling it but with no success. Thank you so much!
BloodBankTalk: Antibody / Antigen Reaction
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