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As thyroid FNAB is used as a screening procedure to select nodules to address to surgery, a major issue is
to reach a high sensitivity while keeping low costs. Three steps have been shown to increase the probability
to obtain a representative sample: a) clinical evaluation of the thyroid nodule(s); b) ecographic
evaluation; c) rapid assessment of sample adequacy by immediate microscopic evaluation. Ideally, the
aspiration would involve, therefore, a clinician (for clinical evaluation), a radiologist (to perform echography)
and a cytopathologist (for rapid assessment of sample adequacy). Both in USA and Europe, the
aspiration is performed by a clinician in approximately 60 % of cases, by a cytopathologist in 6–8% of
cases and by a radiologist in 2–3% of cases31. At Karolinska Intitute both the aspiration and the
cytological examination are performed by a special Cytology Unit32. Ravetto et al.27 have recently
reported that, when a clinician and a cytopathologist jointly take part to the aspiration procedure, inadequate
samples are kept at a minimum (<2%), even in the absence of rapid microscopic sample assessment,
that would increase costs and procedure time. In our Institution, thyroid FNAB is centralized, and
only two clinicians, with special interest in thyroid perform all steps, including clinical assessment, nodule
aspiration, echographic assistance and cytological evaluation. This setting has resulted in a good
accuracy and in low inadequate sampling rate and low costs25 and unpublished data. In any case, there is ample evidence that the rate of inadequate samples is inversely related to the operator experience with the highest inadequacy rates being found in Institutions where poorly trained clinicians perform the aspirates33. |
