Objective To explore the value of ultrasound risk stratification combined with BRAF^V600E gene mutation detection in diagnosing category Ⅲ thyroid nodules in the Bethesda System for Reporting Thyroid Cytopathology (BSRTC).

Methods A total of 158 patients with thyroid nodules were conducted ultrasound examination for risk stratification and BRAF^V600E gene mutation detection. Taking the pathological diagnosis results after operation as the gold standard, the diagnostic accuracies of ultrasound risk stratification alone and its combination with BRAF^V600E gene mutation detection in the diagnosis of BSRTC category Ⅲ thyroid nodules were analyzed.

Results Among 158 thyroid nodules, 96 nodules were malignant and 62 nodules were benign. A total of 95 highly suspected malignant nodules and 63 moderately suspected malignant nodules were evaluated by ultrasonography. There were 80 nodules of mutant type of BRAF^V600E and 78 nodules of wild type BRAF^V600E, and the sensitivity, specificity, accuracy, positive predictive value and negative predictive value of mutant type of BRAF^V600E to malignant thyroid nodules were 83.33%, 100.00%, 89.87%, 100.00% and 79.49%, respectively. The accuracies of highly suspected malignant judgment and highly suspected judgment in combination with mutant type of BRAF^V600E in diagnosing BSRTC category Ⅲ nodules were 90.51% and 93.67% respectively, and there was no significant difference between two methods (P>0.05). The accuracy of moderate suspicious combined with mutant type of BRAF^V600E in the diagnosis of BSRTC category Ⅲ nodules was 39.87%, which was significantly higher than 9.49% of moderate suspected malignant judgment alone (P < 0.05).

Conclusion Ultrasound high risk stratification combined with BRAF^V600E gene mutation has a high diagnostic accuracy for BSRTC category Ⅲ thyroid nodules, and BRAF^V600E gene mutation detection can increase the accuracy of ultrasonic diagnosis of BSRTC category Ⅲ thyroid nodules in moderate risk stratification.