[Histonet] Re: O Fix

[Bob Richmond]

Vicki Gauch at AMCH in Albany, NY asks:

>>I have been asked to post a few questions regarding O FIx. Is anyone
using this for their lymph node cases? Any pros or cons? What is the
fixation time versus 10% NBF? Have you had any staining issues on H&E,
special stains or immunohistochemistry? Does it require special disposal
method?<<

Surgipath's O-Fix is described as containing formalin, acetic acid, and
alcohol. It's probably fairly similar in composition to Davidson's fixative
(3 parts water, 3 parts reagent alcohol, 2 parts 37% formaldehyde, 1 part
glacial acetic acid). I use either of them as a "disclosing fixative" for
finding mesenteric lymph nodes in colon resection specimens, and find them
indistinguishable from each other. I use disclosing fixative in labs where
I'm allowed to. It smells bad, and is difficult to use without adequate
ventilation.

To use them, you must have the specimen unfixed (brief exterior exposure to
formalin is OK), cut off the mesenteries and cut them up, and fix overnight
in the disclosing fixative. Microtomy, H & E, and the ordinary special
stains work very well. I don't know about immunohistochemistry. Obviously
you need to work closely with your pathologist to make the technique work.

You'll have to check with your waste disposal people about disposing of
disclosing fixatives.

Bob Richmond
Samurai Pathologist
Maryville TN