A diagnostic head and neck fine needle aspiration service can be provided using liquid-based cytology only.
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OBJECTIVE: Liquid-based cytology (LBC) has been used for non gynaecological specimens since its introduction into routine use in cervical cytology in the mid-1990s. There are still relatively few large studies comparing performance in reporting the head and neck fine-needle aspirations (H&N FNA) processed by LBC only to conventional direct smears (CDS). METHODS: This study compared 686 H&N FNAs processed by LBC only with 3719 CDS. All were taken under ultrasound (US) guidance by a small cohort of three consultant radiologists and reported by the author. RESULTS: The (smaller) LBC sample was statistically representative of the larger CDS population at an alpha level of 0.05. There was no difference between CDS and LBC at a 95% confidence interval (CI) when comparing specificity and sensitivity (specificity: 94.8-96.5% versus 90.2-95.4%; sensitivity: 91.4-94.1% versus 86.8-93.4%). The inadequate rate between the two techniques was similar, 0.5-1.0% for CDS versus 0.7-2.5% for LBC. The significance difference was in the suspicious rate which was greater at 2.8-5.8% for LBC versus 1.7-2.6% for CDS. Consequently, there was a slight but non-significant difference between the two populations with respect to the overall accuracy: 93.5-95.1% for CDS versus 89.4-93.7% for LBC. CONCLUSIONS: While there are morphological differences between LBC and CDS in H&N FNAs, once a degree of familiarity is achieved, the two techniques have equivalent sensitivity, specificity and inadequate rates.