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Posts posted by Clarest
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On 6/19/2017 at 11:38 AM, BldBnker said:
Why couldn't you give B blood (packed cells)? The Anti-A1 would be avoided and the blood would be compatible. AB is the "universal receiver" after all. Just curious.
As Malcolm mentioned " as the anti-B in those units tend to be of lower titre and avidity than does the anti-A in either group B or O units". The patient is group AB and the red blood cells have A and B antigens.
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Hi Mabel,
We use the tube saline IAT method for crossmatch and it is allowed to skip the immediate-spin phase. So, as long as the anti-A1 does not react at 37C, we have no problem to result the compatibility of the crossmatch. Routinely, it is okay for us to give group O or B blood for patient's with anti-A1 and that's what technologists prefer to do as it only requires immediate spin. However, for this particular patient, we just wanted to be more careful.
Clarest
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QuoteOn 6/17/2017 at 11:40 AM, Malcolm Needs said:
Well, you can't rely on my memory - it wasn't Transfusion at all, but Vox Sanguinis! The reference is as follows:
Zaffuto BJ, Conley GW, Connolly GC, Henrichs KF, Francis CW, Heal JM, Blumberg N, Refaai MA. ABO-immune complex formation and impact on platelet function, red cell structural integrity and haemostasis: an in vitro model of ABO non-identical transfusion. Vox Sanguinis 2016; 110 (3): 219-26.
Thanks a lot Malcolm!
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Hi tkakin,
You're right that anti-A1 typically reacts at immediate spin and that's reason for us to give group A or AB IAT crossmatch compatible red cells. On the other hand, if the group A or AB units are IAT crossmatch compatible with patient's plasma, it proves the anti-A1 does not react at 37C.
Clarest
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Hi Malcolm,
We gave group A IAT crossmatch at first when group AB was not available in our stock. Then, we particularly ordered group AB units to hold for this patient. I am really interested in the paper you mentioned in your post regarding AB antibodies. When you have time, could you please share it with us?
Thanks a lot.
Clarest
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Thank you Malcolm. We do not usually keep group AB red cell units in our stock.
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Hi all,
If a sickle cell disease patient is group A2B with anti-A1 (seems no reactivity at 37 degree), which ABO group of donor cells is the best choice for transfusion, group O or B immediate-spin crossmatch compatible, or group A IAT crossmatch compatible? Thank you for your reply.
Clarest
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Thank you all for your replies. They're really helpful.
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Hi all,
We have a patient with strong rouleaux and an alloantibody. According to our policy, we need to perform a full crossmatch which means the crossmatch is carried from immediate spin, to 37C and to AHG phases. Due to the strong rouleaux, a saline replacement technique has to be used during the immediate spin crossmatch phase. I am wondering if the 37C and AHG crossmatch tests can be continued on the tube that has been done with the saline replacement.
Thank you,
Clarest
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Hi all,
In the chapter 22 of 17th and 18th editions of AABB Technical Manuals, it states that "Multiple IM (intramuscular) doses should be given at different sites or at different times within 72 hours". I am wondering how to define the "multiple", more than one or 5 doses. The reason I mention "5" here is that in my previous and current working places, they either says "No more than 5 doses of RhIG should be injected intramuscularly at one time" or "If more than 5 vials of RhIG are required, they should be spaced out over 72 hours." I tried to find the base of these statement from the product inserts or monograph, but not successful. Could anybody share some information on this? Thank you.
Clarest
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We're using an automated solid phase system and it has an similar issue sometimes, not always. Usually, the ab. screen is positive with both screening cells (usually 2+ or below) and the panel is totally negative on the same testing platform. As the LISS tube and manual solid phase methods are our backup methods, for the situation like this, we usually repeat the antibody screen with both backup methods (the same lot of screening cells is used for automated and manual solid phase tests, and different screening cells are used for LISS tube method) and if both (LISS tube and manual solid phase) are negative (majority of the cases), we usually think it's something wrong with the automated analyzer (report to the analyzer vendor) and result the antibody screen negative. Otherwise, if the manual solid phase ab. screen is positive and the LISS tube method is negative (plus the solid phase panel is negative), we suspect it's something particular with the lot of solid phase screening cells and conclude "All common clinically significant antibody ruled out" and perform a full crossmatch if blood is required. If the repeat is positive with both the LISS tube and manual solid phase or only with the LISS tube, we set up a LISS tube panel for further investigation (So far, we haven't had this scenario, yet.).
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23 hours ago, exlimey said:
Enzyme-treated cells can be very useful in the hands of expert serologists who know the pros and cons of their use. Routine use by front-line techs is probably ill-advised.
In this case, some level of feasibility testing might be useful before switching to an enzyme-treated panel, but I would hesitate to call it "validation". Each facility should determine if such a panel is useful to them, or if it would cause more problems that it would solve.
As I mentioned in earlier in this thread - I believe these are FDA-license reagents and they do not require validation.
Thank you very much exlimey. Really appreciate your input.
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We call it "Passive anti-D" and put a comment "Anti-D probably due RhIG received on [date]" . If the antibody screen is still positive, we do a saline IAT crossmatch. If later on, the screen becomes negative, we just do an immediate-spin crossmatch. Sorry, we haven't startred electronic crossmatch yet.
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I would like to know, as well. We're planning to change one regular panel to an enzyme panel and wondering how should the validation be done.
Clarest
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Hi,
Could anybody answer my above question regarding how to define the acceptable range after the validation slides are read? I really appreciate your help.
Clares
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On 11/21/2016 at 7:14 AM, David Saikin said:
AABB and CAP do not have a minimum sample requirement. In your validation document you should determine how many samples you need to run. Just as an aside, if you could find a Thal minor patient they provide an interesting specimen as they have a persistence of fetal hgb.
Hi David,
I was thinking something similar such like a sample from a patient with an elevated hgb F. Thank you for your suggestion. We're planning to manually make 14 positive samples (as we do not have that many positive samples routinely) with different percentages (0.1% to 10%) of positivity, plus 6 negative samples to make a total of 20 samples. The problem is to define the acceptable range of each positive sample after being read. For example, I make up a positive sample with about 2% fetal cells. After the technologist reads the slide, what is the acceptable range to prove that the staining method is valid. We do not have a flow cytometry to check for us. I notice that CAP usually gives a wide acceptable range for KB proficiency testing. I am wondering if anyone could give some suggestions or share a validation protocol of KB testing method. Thank you in advance.
Clarest
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Thank you very much cheru26 and scott for your help.
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Hello there,
It has been some while since last time I was here.
We're planning to validate a new Kleihauer Betke staining method as our current one does not work well (especially with CAP samples) and trying to determine # of samples required for this validation. We couldn't find any requirement/standard to specify the # sample needed to fulfill the purpose of validation. Could anyone please provide some related information? Thank you for your help.
Clarest
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Hi R1R2,
I have the same Rh type (R1R2) as you do. Thank you for your 3 points.
Yes, we use gel IAT to test the cord plasma.
I don't think we're going to implement this practice of testing cord blood for TSB very soon as our biochemist wants to have an extensive validation first. I just couldn't get the point why the management hadn't discussed this with the biochemist before they promised the clinical team that this practice could be implemented within 2 weeks. I guess to them, all the lab needs to do is changing the normal range on the SOPs.
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Hi Dansket,
It seems like that the Paediatric Patient Care Team wants all the babies with a positive DAT to have bilirubin checked, as well as the ones who have clinical signs and symptoms of jaundice. I hope they do not rely on a positive DAT too much to decide if a bilirubin test is required, but the signs or symptoms. In their new procedure, they really stressed that all newborns that test DAT positive will have a total serum bilirubin (TSB) done on cord blood and mainly discussed about the critical level of cord TSB.
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Hi all,
Our Paediatric Patient Care Team would like the technologist working in Blood Bank to send all the cord blood sample (EDTA tube) with positive DAT to Chemistry for total serum bilirubin test. However, in my current working hospital , the Blood Bank policy with the DAT-positive cord sample is:
1). If the mom does not have an allo-antibody and the ABO maternal-fetal incompatibility presents, there will be no further workup and conclude the positive DAT as "positive DAT due to ABO maternal-fetal incompatibility";
2).If the mom has an allo-antibody/antibodies, an elution and antibody identification will be performed and the conclusion may be "maternal anti-[specificity] was eluted from the infant's red blood cells".
If Blood Bank follows their request to send the cord blood to chemistry, in order to complete the further workup described in the above 2),we need to ask the sample back from chemistry after the bilirubin test is done, which means the sample has to be passed back and forth between Blood Bank and Chemistry. The idea does not sound attractive. How do you think?
Actually, in the Blood Bank where I worked before, for the situation like the above 1), we usually set up IAT test using cord plasma against pooled screening cells and A1 or B cells to confirm the positive DAT is due to ABO incompatibility, not an antibody to a rare blood group antigen. For the situation in 2), besides perform an elution, we also phenotype the cord cells (if possible) and set up and IAT antibody screen and selected cells to confirm the presence of maternal antibody in the cord's plasma.
Which one (current or previous hospital's policy) do you think is better? What do you do in the scenarios like the above in your hospital?
Sorry for the long post and thank you for sharing your experience!
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To those who use LISS tube method, do you perform any quality control on LISS reagent? If yes, could you please share how often and how you do it?
Thank you in advance.
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Hi tigerlilly415,
When you performed the correlation study with 20 known positive antibodies, did you only do antibody screen or antibody screen and panel? Besides doing this correlation study, when you converted the testing method from tube LISS to tube PeG, did you do any other validation for tube PeG method? If you did, how many samples were used in validation and what was based on to decide the number of samples needed for validation? Thank you for your help.
Inputs from other members are also welcomed and appreciated.
Elution Studies
in Transfusion Services
Posted
We do exactly the same as Laurie said.
I would like to take this opportunity to do another survey related to elution studies.
1. After a patient was transfused a couple of days or a week ago, we received a sample and did elution on it due to positive DAT with IgG. Then, several days later (no transfusion after the last elution) , another sample was received and the DAT was still positive with IgG. Do you do another elution as the patient has been transfused in the last 3 months?
2. If a patient has an autoantibody ( DAT is always positive with IgG) and has been frequently transfused (please do not ask me why?), do you do the elution on every post-transfusion sample received (e.g., every 96 hours or weekly) before crossmatching for the next transfusion? If not, how often do you perform the elution if the positive DAT (i.e. strength of the reaction) on the current specimen is not stronger than the DAT performed on the last specimen, and the antibody screen/panel (i.e. strength of the reaction) on the current specimen is the same as on the last specimen?
Thank you.