RE: [Histonet] RE: Microwave Tissue Processors

From:"Tom Pella"

Sorry to jump in so late on this question. I have read the rest of the
answers with interest. Here are a few things to consider:

1) FDA registration of a microwave unit is required for use in a histo lab
in the USA; that is, the manufacturer needs to list their unit with the US
FDA. To my knowledge, the only microwave tissue processor listed with the
FDA is the PELCO HistoWave, also having been sold as the Thermo Shandon
2) The National Committee for Clinical Laboratory Standards ("NCCLS", which
is now global and considering a name change to reflect that) has had a
committee working on microwave standards in the histology lab for a long
time now. I'm not sure, but I believe that this effort might be coming to a
conclusion soon. I believe that several members of Histonet are on this
committee. I'm not sure what kind of information is available on what it
will be, but it is not yet in effect. Since NCCLS documents often are used
to help create government standards, this will have an impact on histo labs
that use microwaves for tissue processing.
3) The CAP Today article from October mentioned in another related email (I
believe it was the one on microwave processing) describes a unit that is not
yet for sale, but points to a direction that I believe will eventually take
the histology tissue processing process by storm; that is, automated tissue
processors that use a microwave. All of today's automated processors simply
automate bench processes without accelerating them, which is good but leaves
lots of room for speed improvements. Microwaves uniquely offer that
possibility of speed improvement. A good microwave tissue processor,
completely manual, can already run circles around the turnaround time of any
of today's automated processors. I believe it's only a matter of time when
all vendors who produce automated processors will come out with new models
that incorporate a microwave in them; as the CAP article indicates, the time
savings are a quantum leap over today's units.
4) Regarding Julee Chan's request on decal, we offer a unit that avoids the
stronger corrosive acids like formic, rather using EDTA, and can do decal
quickly with it. Heat is eliminated (it can process at ambient temperature,
down to 4 degrees C). I think you will achieve superior staining results
when you keep temperatures in the microwave low for both fixation (except
for a brief time after diffusion) and decal. With our unit, there is no need
to "let samples sit" for any length of time in formalin prior to fixation or
EDTA prior to microwave decal.
5) I couldn't agree more with the comments on use of a lab microwave v. a
kitchen microwave. There have been discussions before on Histonet about
safety considerations, considerations of consistent processing results,
equipment features, etc. that should persuade anyone who is serious about
getting good results safely to only use a lab microwave. But I think there
are easier ways to do antigen retrievel than in a microwave, though it's
certainly possible.

Tom Pella

-----Original Message-----
[]On Behalf Of Hallada,
Sent: Tuesday, October 28, 2003 8:43 AM
Subject: RE: [Histonet] RE: Microwave Tissue Processors

I was wondering if anyone out there is using a microwave tissue processor
for routine hospital tissues. Are there any regulations applicable to
instituting one, ie FDA approval?
Teri Hallada BS MT CT (ASCP)

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