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Updated: Apr 17, 2026
Substernal Thyroid Biopsy Using Endobronchial Ultrasound-guided Transbronchial Needle Aspiration
Published on: November 10, 2014
Reducing indeterminate thyroid FNAs
Andrew A Renshaw1, Edwin W Gould
1Department of Pathology, Baptist Hospital, Miami, Florida.
Background:
The Bethesda System recommends limiting the percentage of cases diagnosed as indeterminate in thyroid fine-needle aspirations (TFNAs). However, studies are lacking that document how to decrease the rate of indeterminate TFNAs and its effects.
Methods:
The authors modified the Bethesda criteria to reduce the rate of indeterminate TFNAs ("atypical cells of undetermined significance" and "suspicious for a follicular/Hurthle cell neoplasm") by reassigning cases that may have been categorized as indeterminate to "suspicious for papillary carcinoma" or "favor benign" for an 18-month period and correlated this with histologic follow-up.
Results:
The indeterminate rate decreased from 14.4% (Bethesda) to 8.2% (modified Bethesda; P < .001). There was no significant difference in the risk of malignancy for the 2 groups (23.6% vs 17.3%, respectively; chi-square P = .39). There were 6 false-positive diagnoses in the Bethesda group compared with none in the modified Bethesda group (P = .06). In the Bethesda group, but not in the modified Bethesda group, the indeterminate rate was correlated with the overall rate of malignant and suspicious for papillary carcinoma diagnoses.
Conclusions:
Modifying the Bethesda criteria can decrease indeterminate TFNAs diagnoses without a significant decrease in the risk of malignancy. The modified Bethesda criteria, but not the Bethesda criteria, are independent of the malignancy rate.
