Dansket

By definition, reagent reverse grouping A1 and B cells are used to detect anti-A and anti-B antibody in patient plasma. Accordingly A1 cells should react with anti-A but not with anti-B, and B cells should react with anti-B but react with anti-A. Therefore, A1 cells should not be agglutinated by anti-B. No agglutination is a negative test result, i.e., a negative control test. Likewise, B cells should not be agglutinated by anti-A. No agglutination is a negative test result, i.e. a negative control test. Testing A1and B cells with AB plasma, Diluent, Albumin or saline may demonstrate that the test cells are not spontaneously agglutinating in their presence which serves as a negative control for those reagents, but does not serve as a negative control test for A1 cells or B cells.

To amaze you and challenge your statement, "I would be amazed if manufacturers would make such a direction". I provided three examples of Anti-D typing reagents that did give such direction. For patient testing, ORTHO requires an interpretation of Rh Positive (assuming a negative control test) if a positive test result (presence of agglutination) is demonstrated with any of their Anti-D typing antisera (liquid or Gel). For your further amazement and amusement, please read the following from CAP announcing 2018 revisions to the Transfusion Medicine Checklist, "Also clarified in the 2018 checklist is that the use of molecular-based screening assays alone for ABO and Rh(D) blood type assignment is unacceptable for transfusion or transplantation. “We still do not know completely everything about ABO and Rh molecular typing,” Dr. Gandhi says, which is why TRM.40550, “Forward/Reverse Typing,” now says an FDA-cleared or -approved serological method must be used. ABO/Rh typing for transplant or transfusion has to be done “by an FDA-approved method, and right now that’s only serology,” Dr. Gandhi says. “We use molecular-based testing for a lot of blood bank phenotyping now,” Dr. Park says, “but it is not acceptable and it’s just not the right testing and methodology for ABO and Rh.” ABO and Rh typing by molecular methods is complicated and not without risk, she says, adding, “Serology is very simple, so go with the simple one that works well.”

Malcolm, With all due respect, you have completely misinterpreted my original response to sunshine's post quoted above. As sunshine stated, he/she is a Transfusion lab. So his/her post refers only to recipient testing as does my response. I do not disagree with any of your statements regarding Rh typing of donors, but they are irrelevant to my response to sunshine's post . Secondly, sunshine states that he/she interprets a 1+ test result with Rh tube typing as Rh Neg. It is this statement to which my post is directed. If sunshine is using ORTHO Anti-D, either liquid or gel (and I don't know if he/she is using ORTHO), he/she is not following the manufacturer's Instructions For Use. Not following direction insert (for FDA licensed antisera) is not justified by criticizing the manufacturer, or referencing some guidelines, or citing scientific literature. Maybe this is not an issue for you in the UK, but it is in the US.

For example, Ortho-Clinical Diagnostics produces three Anti-D products in the United States (see attached files). Instructions for Use of each antiserum state that the presence of agglutination is a positive test result and is interpreted as Rh Positive when the Rh Control test is negative. I get that the scientific community is not 'in-sync' with the regulatory or manufacturing communities, but how does one justify not following the Instructions For Use, specifically the interpretation of test results, for a product approved and licensed by the FDA? It is curious to me that veteran posters in this forum have stated consistently that one must follow manufacturer's directions, but now say user does not have to follow the Anti-D direction insert. e631200462_EN.pdf e631207615_EN.pdf MTS-ABDMR_J32851_3_EN (1).pdf

Your statement implies that users do not have to follow the manufacturer's direction insert if they are inspected by CAP and/or AABB. May a transfusion service that is not inspected by AABB/CAP also elect to not follow manufacturer's insert? Please provide the CAP Transfusion Medicine Checklist number from the 2018 edition that references your statement. I am not familiar with "AABB guidelines". Are you referring to the Standards or the Technical Manual?

Does the manufacturer's directions for your Rh tube typing reagent allow for interpreting a positive test result as Rh Neg? If not, how would you defend your policy (that is contrary to the manufacturer's directions) to a knowledgeable inspector?

Was the bare unit directly in contact with the counter or was the unit within some kind of overwrap or secondary container?

However, none of those agencies state that the facility must follow AABB Standards nor do they mention them during an inspection. Only AABB inspectors can cite for non-compliance with an AABB standard.

Based on an observational study of ABO grouping in Gel I reported at the 1997 AABB Annual Meeting, ABO Plasma Grouping discrepancies occurred in 0.8% (26/3183) adult ABO grouping tests in Gel. Anti-B was not detected in 24/26 patients, anti-A was not detected in 2/26 patients, and anti-A1 was not detected in 3183 patients. In comparison, anti-A and anti-B was detected in 19/26 patients by the immediate-spin tube test, and was detected in 7/26 patients after 10 minute incubation room temperature incubation and centrifugation. Based on this study and 20 years of gel testing since that time have shown me the anti-A1 is rarely detected in Gel and that 70-80% of ABO plasma grouping discrepancies are resolved using the immediate-spin tube test. Centrifugation is used quite differently in gel versus tube testing. Centrifugation is used to separate agglutinated cells from un-agglutinated cells within the gel column, but is used to enhance agglutination in standard tube tests by forcing cells together at the bottom of the tube. This may contribute to the increased sensitivity of tube testing in ABO Plasma grouping tests.

Incubating patient plasma with patient red blood cells and then applying the antiglobulin test is no longer a Direct Antiglobulin Test but an Autocontrol test which is an Indirect Antiglobulin Test. Some may think an Autocontrol test gives the same results as a Direct Antiglobulin Test, but that is not always true.

Yes, Major crossmatch only, no minor crossmatch. We don't make a washed cell suspension, just dilute to n% with saline.

Replacing the balance card is on my monthly QC checklist.

Correct, there is no such thing as "anti-Weak D", but the Weak D test is done and it is interpreted as either "positive or negative" (assuming a negative control test). Procedurally, if a Weak D test on a blood sample (that gave a macroscopically positive immune resetting test) is also agglutinated (usually =>2+) , I will interpret that test result as a "positive Weak D test" or "Weak D positive" and report the patient to be Rh Positive.

I think the terms "strongly positive" or "diffusely positive" do not accurately describe the results of an immune resetting test on a Weak D positive blood sample. By definition, the test is routinely read with a microscope. An unexpected result is macroscopic agglutination and this is what we see with a Weak D positive and D positive blood samples. Our procedure states that if macroscopic agglutination is observed in the immune resetting test, then a Weak D test is indicated for that blood sample.

Remember that 1+, 2+, 3+ and 4+ are test results and that test results may be interpreted accordingly to the test being performed and to the user's protocol for Rh grouping. For example, the ORTHO Gel Anti-D direction insert states that agglutination observed in the anti-D gel column should be interpreted as Rh positive (assuming a negative control test), but some users may interpret weak agglutination ( less than 2+) in Anti-D Gel as Rh negative.