Comparison of British Thyroid Association and TIRADS classifications and their impact on the radiological and surgical management of indeterminate thyroid nodules

The British Thyroid Association (BTA) Guidelines for the Management of Thyroid Cancer advocate for fine-needle aspiration cytology for all thyroid nodules graded indeterminate (U3) at ultrasound assessment. This approach raises concerns regarding potential over-diagnosis of low-risk lesions. Conversely, equivalent Thyroid Imaging Reporting and Data Systems (TIRADS) guidelines permit surveillance or discharge of indeterminate thyroid nodules of certain sizes. This service analysis analyses how guideline choice impacts the fine-needle aspiration cytology rate and subsequent surgical management of indeterminate thyroid nodules. All patients with an indeterminate (U3) thyroid nodule identified on ultrasound over a 12-month period were included. Indeterminate thyroid nodules were retrospectively rescored using three equivalent TIRADS classifications by three independent reviewers, blinded to the histopathology. Hypothetical differences in fine-needle aspiration cytology rates and surgical activity were then compared. Ninety-six nodules were identified. Retrospective application of TIRADS guidelines resulted in a hypothetical 44.8–55.2% reduction in fine-needle aspiration cytology performed for indeterminate thyroid nodules compared to BTA. A statistically significant increase in rates of surgical activity for indeterminate thyroid nodules was observed between BTA guidance and all retrospectively applied TIRADS guidelines (p < 0.001). Of four confirmed thyroid cancers, three would have been unanimously removed. Under BTA guidance, increased fine-needle aspiration cytology rates for indeterminate thyroid nodules resulted in significantly increased surgical activity in our cohort compared to retrospectively applied TIRADS guidelines. •Indeterminate (U3) thyroid nodules are particularly challenging to risk stratify.•TIRADS application hypothetically reduced the U3 FNAC rate compared with BTA.•Reduced FNAC rates would have resulted in significantly lower surgical activity.