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Technical
EQA - What is a good Papanicolaou Stain?
A NHSCSP working
party has formulated a national scheme for a Technical EQA, for
which approval will be sought in the coming year. Mike Rowell gave
us a taster of what this would mean. he gave us a few pointers which
should help us apply self criticism to our staining parameters and
survive EQA scrutiny.
- Select only
negative slides, as there is a bias towards calling a smear well-stained
if dyskaryosis have been detected.
- Select single
cells in a well-fixed area with little or no background inflammatory
esudate.
- Look at nuclear
colouration, differentiation and contrast.
- Look at cytolplasmic
colour balance, intensity of individual colours, and translucency.
Mike projected
ten slides of varying staining qualtiy. He invited two members of
the executive panel to act as 'expert markers', and us delegates
were given a sheet on which we rated this staining quality. We can
be encouraged that we are consistent at assessing what a good Pap
stain is. Most of the people I asked had agreed with the panel markers
to one mark (out of ten) on the slides projected.
Those labs that
have been involved in the pilot scheme affirm the value of the scheme.
they claim that there has been an overall improvement in standards,
that it prevents isolated over-confidence, and that friendly rivalry
is a good thing.
Gary Gill, who
writes with great authority (especially about stains) to the Cytopathnet-L
listserve, was asked for a prescription of the 'best possible' Pap
stained smear - if it exists. His answer was that 'herding cats
is simpler than coming to consensus on Pap stain quality'.
Mike agreed
that personal preference would always win.
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