|
Christine Payne from the Royal Went Hospital in Newport gave
a very interesting talk on the non-gynae applications of liquid
based cytology at the TVCS meeting at Watford General Hospital on
10 November 2001.
She listed several
advantages of using the process.
- better productivity,
- better utilization
of time,
- superior
preparations and
- standardisations
of techniques.
- improved
quality of each slide prepared in this manner means that only
one slide per sample need be examined.
There are, however,
disadvantages in using this technique:
- preparation
time may be lengthened
- it is not
designed for air-dried samples
- may be costly
- staff must
be trained in both preparation and microscopy of the samples.
Christine then
described the features of the ThinPrep 2000 machine and briefly
described the principles behind the preparation of samples. Essentially
the sample is concentrated by centrifugation and the added to a
solution which is mucolytic and haemolytic. The cells are randomly
dispersed using a vortex and then drawn through a filter. Inflammatory
cells pass through the filter giving a rich concentration of diagnostic
cells for assessment. Most samples can be prepared successfully
on the machine, preservation of urines being particularly good.
Our attention was drawn to the practical considerations involved
in the use of the machine (sighting, storage of vials etc) and the
need for QC procedures and checks at all stages was emphasized.
The microscopic
appearance of the finished preparations was described fully:
- a clean background,
- excellent
fixation
- well defined
nuclear detail
- the removal
of many of the red cells in blood stained samples may mean malignant
cells can be demonstrated easily in samples where they previously
would have been difficult to visualise.
There are however,
limitations of the technique, principally in the preparation of
thyroid samples. Colloid is an important diagnostic feature of thyroid
FNA samples; this passes through the ThinPrep filter and therefore
is not present in the final preparation.
Christine then
outlines several cases which illustrated the diagnostic value of
LBC technique. The Royal Gwent laboratories experience of using
thin prep in their head and neck FNA clinic was outlined. The use
of this technique allowed time saving in both clinic attendance
by cytology staff and in screening of fewer preparations, coupled
with a decrease in the number of non-diagnostic slides. The audience
was left in little doubt that non-gynae preparations of the future
would be reliant on some form of LBC technique.
|