[Histonet] Floater sources

Kemlo Rogerson Kemlo.Rogerson <@t> waht.swest.nhs.uk
Thu Sep 6 02:17:36 CDT 2007

I was reading some of the old archived messages on floaters, and being
somewhat new to the field of histotechnology was curious about how
floaters can be attributed to a particular tech who performed work on
the block. For example, couldn't other sources of contamination be from
the automatic stainer, processor carryover (cassette not completely
closed/or if closed, friable tissue through the slats eg if sponge not
used on larger specimen). In some previous labs I've worked in- floaters
were quickly attributed to the cutter, embedder or grosser and might
result in a "write up". If the floater is seen in the block how can you
differentiate if it came from the grosser carryover/embedder
carryover/processing carryover/unsigned re-embedder/or even possibly
even client carry over between patients or different specimen types of
the same patient. And if it is not in the block --differentiating
between the cutter/automatic stainer (I've seen specks of tissue debris
in automatic stainers/ sections falling off the slides and into the
reagents etc). Obviously all should be done to minimize the factors, but
I'm just not clear how a single source is pinpointed and potentially
blamed for the event (depending on the lab policy). Thanks for any ideas
on this. 

You are exactly correct, floaters can be attributed to a variety of
causes, processing machines that aren't regularly changed, transfer on
the cutting up forceps, on the waterbath and on the forceps of the
embedder. If the floater was from a block that was cut, embedded, cut up
before the section with the floater then the culprit is obvious. If the
section was cut by someone who didn't cut the block from which the
floater floated, then the culprit is the embedder, machine,or cutter up.
Realisticaly I would have thought that most floaters would be from the
embedder, cutter up, then sectioner as the latter has the greater
likelihood of seeing the error of his/ her ways. Waxy forceps of messy
forceps, in my experience are the usual culprit but in some instances,
necrotic tumours can shed cells in the processor and even the stainer.

Floaters are usually obvious as they tend to be at a different level
than the tissue section and I'm afraid they are a fact of life. You can
reduce the incidence but sadly never eradicate them.

Kemlo Rogerson
Pathology Manager
DD   01934 647057 or extension 3311
Mob 07749 754194; Pager 07659 597107;

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