Blood flow grade 3 is defined as blood flow signal grade 3, which generally means that blood flow is abundant and 2 vessels with clear walls or 4 or more punctate blood flows are visible within the mass, which helps to determine the benign or malignant nature of the tumor. The vascular signal, i.e. the richness of blood flow, can be classified into four grades by color Doppler flow imaging. Grade 0 generally refers to the absence of blood flow signals under ultrasonography; Grade 1 suggests that there is a small amount of blood flow in the mass, with one to two punctate blood flow signals; Grade 2 suggests that there is a moderate amount of blood flow in the mass, with one blood vessel with clear walls or three to four punctate blood flow signals; and Grade 3 suggests that there is an abundance of blood flow in the mass, with two blood vessels with clear walls or more than four punctate blood flow signals. Some studies have confirmed that malignant masses are richer in blood flow than benign masses, with malignant masses mostly having grade 2-3 blood flow and benign masses mostly having grade 0-1 blood flow, so the richness of blood flow is helpful in determining the degree of benignness or malignancy of a mass. However, the size of the mass also has a certain effect on the richness of blood flow, and rich blood flow signals can be observed in some larger benign tumors, while no blood flow signals can be seen in some smaller malignant tumors. This may be related to the small size of the tumor, which results in few neovasculature or fine diameter, as well as the limitation of the sensitivity of the instrument. In addition, color Doppler flowmetry can provide information on the direction of flow, flow velocity, and distribution of blood flow, which can indicate different clinical significance. Consultation with your physician is recommended for interpretation of the results.