Breast ultrasound category 5 generally refers to the five-level classification method of breast ultrasound, known as the BI-RADS classification method. The evaluation criteria used for breast ultrasound is the BI-RADS classification method, which can be categorized into 5 classes. It is mainly used to determine the nature of a lump by examining the size of the lump, the blood flow around the lump, and the clarity of the border through color ultrasound, molybdenum target and nuclear magnetic examination of the breast. Grade 0 is generally unable to categorize the lesion and needs to be further evaluated with imaging tests. grade 1 is negative, usually without positive signs. grade 2 is a benign lesion, and grade 3 suggests that the lesion may be benign and needs to be followed up regularly. Grade 4 is suspicious for malignant lesions and requires pathologic biopsy to clarify its nature. Grade 5 is highly suspicious and usually requires appropriate treatment. The five-grade classification of breast ultrasound can be used to determine the nature of breast lumps. Usually, most of grade 3 and below are benign lesions that require regular follow-up, while grade 4 and 5 are considered malignant lesions and should be consulted promptly and treated by doctors.