Objective: To evaluate the validity of new ultrasound classification in diagnosing malignant thyroid nodule keeping fine needle aspiration cytology (FNAC) as gold standard.

Materials and Methods: This validation study was carried out at hospital from September 06-2020 to March-2021 in Children Hospital and Institute of Child Health Multan .A total number of 114 patients who presented with inflamed thyroid nodules were included. General information regarding patient like name, age and gender was documented for data collection. Ultrasonography was done using Linear 7.5 MHz and curvilear 3.5 MHz transducer all patient in supine position and comfortable setting. Features of ultrasound were recorded. Patients having U4-U5 score were labelled as having malignant lesions. All cases were followed up by fine needle aspiration and corresponding histopathology report.

Results: Mean age of patients was 46.06±10.34 years. Out of 114 patients, 83 (72.81%) patients were female and only 31 (27.19%) were male. On ultrasonography, malignancy was diagnosed in only 24 (21.05%) patients, and remaining 90 (78.95%) were diagnosed of having benign lesions. On histopathology, malignancy was diagnosed in 25 (21.93%) lesions, while remaining 89 (78.07%) patients were diagnosed of having benign lesions. Sensitivity of ultrasound U-score in diagnosing malignant thyroid nodules was 88%, specificity was 97.8%, PPV was 91.7% and NPV was 96.7%.

Conclusion: New sonographic classification system has a reliable accuracy for differentiating malignant from benign solid thyroid nodules. So it can be used as preferred radiological scoring system for initial investigation for solid thyroid nodules.

Keywords: Thyroid nodules, ultrasound U-Score, Histopathology, Malignancy, Diagnostic accuracy.