Should we apply suction during fine needle cytology of thyroid lesions? A systematic review and meta-analysis

Fine needle aspiration cytology (FNAC) is a well-established investigation in thyroid disease. Fine needle sampling without aspiration (FNS) is less commonly used but often easier to perform. Both methods have advantages and disadvantages but, as yet, there is no agreement on which method produces better specimens for cytological diagnosis. We undertook a review of the literature and performed a meta-analysis of the results of four cross-over trials. The resulting odds ratio favoured FNS (OR = 0.99; 95% CI 0.88-1.11) but was not statistically significant. A fifth paper not included in the meta-analysis reported results in favour of FNS (P = 0.003). There is no evidence from the meta-analysis that one method is superior to the other; however, taking into consideration all available evidence, it seems that FNS may be easier to perform and may produce better samples.