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SMW

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SMW last won the day on September 28 2014

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  • Birthday 09/30/1914

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  1. What does the manufacturer's directions for the anti-D reagent in use say to do?
  2. SMW

    KB stain

    Never heard of this, however if the fetal cells are/were ABO incompatible with the mother, e.g. mother group O, fetus group A, the fetal cells would be hemolyzed/destroyed therefore not detectable in the maternal blood sample. Do you know why they're requesting this and how they intend to use the results?
  3. Most anti-E and anti-c reagents are not intended to be tested at the antiglobulin phase. If the control in use as perscribed by the package insert (which is generally not at the antiglobulin phase) was negative, the test results are valid.
  4. Physician signature is required by FDA so that would trump any local or state laws or rules for other providers to sign. See 21CFR 606.160((3)(v): Emergency release of blood, including signature of requesting physician obtained before or after release. Note that the signature is required for the emergent release of the blood and not necessarily the transfusion. Also note that the requesting physician may not necessarily be the transfusing physician.
  5. As I read the initial scenario presented, there was a miscarriage so I didn't think a fetal sample was available or tested? I believe the speculation is that it could have been fetal cells that were D-positive resulting in the initial weak positive testing result.
  6. Some ABO antibodies are very potent and can result in in vitro hemolysis even when using plasma so I don't feel the EDTA sample necessarily precludes the possibility of in vitro hemolysis occurring. For the testing scenario presented, it was only the ABO antibodies that appeared to trap the minor population of cells. This did not occur with the anti-D reagents in use, perhaps they were not as avid. This was reported by many different labs/staff with many different reagents. So based on previous experiences it seems it could be possible that when the initial testing was performed there was a mixed population of cells that were not detected with the avid ABO reagents since the minor population was trapped in the agglutinates, however the minor population was detected with the less avid anti-D reagent. At a later testing period of the same sample, all of the fetal cells could have been hemolyzed in vitro in the collection tube (not the tube actually mixed with the monoclonal antibody and used for testing), and would no longer be detectable with the anti-D reagent. Unfortunately it is not possible to re-create the "initial" sample in the same time frames to test this theory. however it seems to be a potential explanation to this mystery among others.
  7. If there were 2 populations of cells, and if the fetal cells were ABO incompatible with the maternal sample however D positive, the fetal cells could have been hemolyzed in vitro by the time the sample was retested 10 hours later. Since the fetal cells were no longer intact, the repeat testing would have been on exclusively maternal cells and tested as D-negative. I realize your initial forward type did not detect/report the presence of mixed field agglutination. With monoclonal ABO antibodies and using tube testing, it is often very difficult to detect mixed field reactions with small populations of other cells. It seems the monoclonal ABO antibodies are so avid, the agglutinates seem to "trap" the other population of cells in the agglutinate rather than remaining free to be resuspended. This was demonstrated years ago when the AABB offered "damp" workshops where samples were provided for testing, registrants reported their results and results were tallied and presented to attendees. During the time when the older polyclonal ABO reagents were still in use and the monoclonal reagents were just being introduced, the results indicated a significant difference in the detection of mixed field agglutination in the forward ABO testing between the groups using polyclonal reagents (MF detected) vs. monoclonal reagents (MF not detected).
  8. If you are simply making aliquots, e.g., just providing a smaller sample of the same product, FDA registration is not required. If you're making a new product or doing other manipulations, such as adding Plasma to Red Blood Cells to create a Reconstituted Whole Blood unit or washing the RBCs, then FDA registration is required.
  9. Earlier this week at the 2015 AABB Annual Meeting "Ask the Standards" session, the AABB confirmed testing performed by the donor center as specified in this standard, DOES meet the intent since the Standard does not specify WHO does the testing, only that it be performed before transfusion.
  10. See Standard 5.12. Before transfusion, the ABO of...component and the Rh type...labeled as Rh negative shall be confirmed by a serologic test from an integrally attached segment....... Although this standard is in the transfusion service related activities section of the Standards, some donor centers perform this testing so the transfusion services do not need to repeat. Note that the standard does not specify WHO does the test, only that it be performed. If your donor center is not making these claims on the products distributed to transfusion services, then only 5.9.5 applies.
  11. I believe you have this backwards. The patient cells, which are more likely to contain reticulocytes, will be lighter and at the top, with the older donor cells towards the bottom. That's providing the patient is not aplastic and is actually producing RBCs. This is the premise behind the reticulocyte separation method which has been used as a method to attempt to phenotype a patient that has been transfused.
  12. If you are in the US, please remember that the "gel" test cannot be used to detect ABO incompatibility, so you should not be using that result alone to determine compatibility. When you're referring to reacting with A cells in their backtype, I'm assuming you mean A1 cells? Since approximately 1 of 5 A units (20%) will be A1-negative, I would encourage the use of these units rather than group O units. Save the group O units for O patients!
  13. My guess would be it was something other than the blood that was infused (inadvertently?) that caused the hemolysis, e.g., a hypotonic solution. They may have also used something other than saline as a cold cardioplegia solution, e.g., water! Hemolysis was a common occurrence years ago (with no transfusions) when water rather than saline was used as an irrigation solution for TURPs.
  14. In my experiences, the problems encountered with maternal blood in tube instead of cord were with the collection process, not the labeling process. The samples were clearly labeled as cord samples, however, however OB did the collection, it contained maternal blood.
  15. Also did not use cord blood results for transfusion purposes. You can never be sure what is labeled as cord blood is actually cord blood and not maternal sample. Blood type differences may help but still better to have a standard practice. On the other hand, if you're transfusing only group O RBCs and AB plasma probably not as significant until sometime after 4 months when the patient is typed again and a different result is obtained. Along the same lines, we also required a neonatal/heelstick sample in cases where the mother was Rh-neg and the cord blood sample tested the same ABO/Rh as mother as confirmation that RhIgG was not required. Did not see discrepancies that often however they did occur and one missed RhIgG prophylaxis resulting in immunization is enough to justify practice.
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