Thyroid fine-needle aspiration: does case volume affect diagnostic yield and interpretation?

OBJECTIVE: To evaluate the effect of case volume on the diagnostic yield and interpretation of thyroid fine-needle aspiration (FNA).
DESIGN: Retrospective case series.
SETTING: An academic tertiary referral center and 2 community hospital centers. PATIENTS: Data were retrospectively reviewed for all consecutive patients undergoing thyroid FNA at these institutions during the 2009 calendar year. MAIN OUTCOME MEASURES: Differences in diagnostic distribution and yield among pathologists and clinicians of differing case volume.
RESULTS: A total of 790 patients underwent thyroid FNA, with the results interpreted as benign (479 [60%]), atypical (166 [22%]), malignant (9 [1%]), or nondiagnostic (136 [17%]). The FNAs were performed by 134 physicians and interpreted by 16 pathologists with varying case volumes. Low-volume pathologists (<50 FNAs interpreted) were more likely to report atypical FNAs (32% vs 13%; P < .001) and less likely to call FNAs benign (50% vs 70%; P < .001) compared with high-volume pathologists (≥50 FNAs interpreted), and compared with expected normative data (benign, P < .001; atypical, P < .001). Atypical FNA findings reported by low-volume pathologist were more likely to yield benign permanent results than those read by high-volume pathologists (64% vs 42%; P < .02). Low-volume clinicians (<20 FNAs performed) were not more likely to perform nondiagnostic FNAs compared with high-volume clinicians (≥20 FNAs performed) (16% vs 15%; P = .47).
CONCLUSIONS: Case volume significantly influences the pathologic interpretation of thyroid FNA, as low-volume pathologists report more atypical and fewer benign FNA results. Case volume did not have a significant impact on diagnostic yield, because thyroid FNAs performed by low-volume clinicians did not result in more frequent nondiagnostic results compared with those performed by high-volume clinicians.