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Tube holder for reading DAT or IAT under microscope

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Quote from Peter D issitt, Applied Blood Group Serology, 3rd Edition, 1985, Montgomery Scientific Publications, page 69, Reading Methods for In Vitro Tests.

"Now that most saline and albumin tests are carried through to an antiglobulin reading reading the question of how to read them does not often arise. THey are usually read macroscopically in order that the cells and serum are left in the tube for progression of the test. A few cells may, of course, be removed and examined microscopically at any stage if this type of reading is required. However, this author has believed for years that routine use of the microscope in the Blood Bank creates far more problems than it solves. Almost any cell suspension, including those in which washed cells have never been exposed to an antibody, if examined carefully enough under the microscope will be found to contain a few small clumps of red cells. Thus, while this author (grudgingly) admits that reading aids such as mirrors or hand lenses are acceptable (for others, he still reads with the naked eye against a ceiling light source himself) does not condone routine use of the microscope. This reasoning also applies to the reading of antiglobulin tests. Again, this author believes that if agglutination cannot be seen with the naked eye, a hand lens, a covex mirror, or the type of microscope in which the contents of the tube are viewed while still inside the tube by placing the tube itself on the microscope stage, IT IS NOT THERE. Were it not for special tests, such as those in which mixed-field reactions may have occured, or when a small percentage of fetal cells might be present in the maternal sample, this author would start a movement to BAN THE MICROSCOPE from the Blood Bank. Enzyme tests for agglutination or following conversions to antiglobulin reading, should NEVER be read microscopically."

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LOL! I knew someone would mention that Malcolm!

Here we only would use a scope to differentiate rouleaux from a "true" weak reaction when getting very weak macroscopic reverse typings or on an IS crossmatch. I am not sure why anyone would think to use it for a DAT or IAT.


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Thank you very much for the comments. I think it is a habbit to look for any weak reaction if macroscopically negative, (except red cell typing or techniques like LISS or PEG) and report weakly positive if microscopically positive.

Yes, read under microscope also help to resolve ABO discrepancies in some cases, rouleaux vs real agglutination, mix-field reaction, .... etc.

Agree that one may choose to spread a tiny portion on a glass slide and read under microscope.

Also, thanks barmotto for the website.


CK Cheng

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  • 7 years later...
2 hours ago, MAGNUM said:

There is also the Fetal Rosetting tests that require microscopic viewing

True, but both the original question, and the question that resurrected this post were referring to antibody/antigen reactions.

I don't think anyone would be made enough not to use a microscope to make that kind of estimate, unless you are using a fluorescence-activated cell sorter (FACS) with Fluorescein (FITC)-labelled anti-D, which is (just a bit) more accurate than is the human using a microscope!

Flow Cytometry.pptx

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My facility has a plastic rectangle with a notch in the middle, not sure if this is its original usage, but it has "American Dade" written on it. It's held in place by the same swing mechanism for regular glass slides.

You could just carve out a piece of wood and sand it, maybe? :D

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