“Thyroid nodule classification 4A” generally refers to a thyroid nodule that is classified as category 4A on ultrasound. Thyroid nodules in category 4A are considered to be of low suspicion of malignancy, have a 2% to 10% malignancy rate, and therefore may be dangerous. Ultrasound is the most important imaging tool for evaluating thyroid nodules. Ultrasound can determine whether the nodule is single or multiple, the size of the nodule, the morphological features of the nodule, and the blood supply status of the nodule. By evaluating the morphological features of the nodule, sometimes in conjunction with its blood supply characteristics, ultrasound can help determine the risk of malignancy in thyroid nodules. If you find a thyroid nodule category 4A, please go to the hospital as soon as possible to avoid delay.