To evaluate the diagnostic value of Bethesda system combined with thyroid imaging reporting and data system (TIRADS) in assessing the malignat risk of thyroid nodules.

Histopathological, cytological and ultrasound (US) data were studied retrospectively for 243 cases after surgery, including 273 thyroid nodules. All thyroid cytopathological slides and US reports were classified according to Bethesda system and TIRADS. Based on histopathological comparison, the sensitivity and specificity were determined for Bethesda category and Bethesda category combined with TIRADS.

The sensitivity and specificity of Bethesda category were 91.0% and 90.3%, respectively. In indeterminate nodules, malignancy rate was 38.7% in Bethesda categoriesⅠ and Ⅲ, and 85.4% in Bethesda categories Ⅳ and Ⅴ. In contrast, combined with TIRADS, the sensitivity and specificity of positive results were 82.4%, 100%, and negative results were 99.5%, 83.8%, respectively. The malignancy rate of TIRADS 2/3a in Bethesda categories Ⅰ/Ⅲ, TIRADS 3b/3c/4 in Bethesda categories Ⅰ/Ⅲ, TIRADS 2/3a in Bethesda categories Ⅳ/Ⅴ, and TIRADS 3b/3c/4 in Bethesda categories Ⅳ/Ⅴwere 3.7%, 81.8%, 45.4% and 100%, respectively.

Bethesda system combined with TIRADS may be helpful to the preoperative diagnosis of thyroid nodules, which may reduce unnecessary repeat fine needle aspiration and excessive surgery.

Ultrasonography; Biopsy, fine-needle; Thyroid diseases; Bethesda system; Thyroid imaging reporting and data system