A retrospective chart and pathology review of consecutive patients at our center that underwent thyroid nodule FNAB and a subsequent thyroid operation was carried out. The final histopathological diagnoses of the thyroidectomy specimens were considered to be the gold standard for nodule diagnosis. To ensure consistency within the study with respect to cytopathological and histopathological evaluations, all cases that underwent thyroid FNAB and/or operation at other institutions were excluded from the study population. All cases of papillary thyroid microcarcinoma (defined as papillary carcinoma smaller than 1 cm in maximum diameter) that were not an index lesion of interest, and thus were incidentally diagnosed by histopathology, were grouped with the benign cases for the analysis. The study population was then grouped according to age (younger than 55 years or 55 years and older) and gender. The cytology slides were evaluated by one or more board-certified pathologists at our center. The FNABs were classified based upon their BSRTC diagnoses, and they were reported by the pathologists as being either unsatisfactory, benign, AUS/FLUS, sFN, sM, or malignant. For cases that underwent multiple FNABs in the current study, the diagnosis of AUS/FLUS was based upon the FNAB that most immediately preceded the thyroid operation. Though influenced by clinical factors, it is common practice at our institution to repeat the FNAB if the initial diagnosis is either unsatisfactory or AUS/FLUS. All cases not reported according to the BSRTC were excluded from the study population. The characteristics of the study population are summarized in Table 1. A ROM for each BSRTC diagnostic category was calculated after grouping cases by either their age or gender. Statistical analyses that compared the ROM between categories were calculated using the Fisher exact test. A p-value less than 0.05 was considered to be statistically significant.