What is the BI-RADS breast ultrasound classification standard?

Generally, breast BI-RADS categories can be divided into BI-RADS category 0, BI-RADS category 1, BI-RADS category 2, BI-RADS category 3, BI-RADS category 4, BI-RADS category 5, and BI-RADS category 6. Patients are advised to seek medical care and follow their physician's recommendations for symptomatic treatment. Specific details are as follows:

1. BI-RADS Category 0

BI-RADS category 0 indicates no obvious abnormalities are seen—no masses, architectural distortion, or suspicious calcifications—and the likelihood of malignancy is very low. No special treatment is required at this stage.

2. BI-RADS Category 1

Category 1 refers to findings that warrant routine annual follow-up examinations. Patients in this category should undergo regular check-ups as recommended by their doctor.

3. BI-RADS Category 2

This category includes benign changes such as calcified fibroadenomas, skin calcifications, fatty lesions, intramammary lymph nodes, vascular calcifications, and other lesions with essentially 0% risk of malignancy.

4. BI-RADS Category 3

This category suggests probably benign findings, with a malignancy risk of 0%–2%. It includes non-palpable, well-circumscribed, non-calcified masses, focal asymmetry, or isolated clusters of punctate calcifications.

5. BI-RADS Category 4

This category indicates a low suspicion of malignancy (2%–10%) and includes palpable solid masses with partially circumscribed margins, such as fibroadenomas suggested on ultrasound, complex cysts, or suspected abscesses. If biopsy results are benign, routine follow-up is still required—this is classified as BI-RADS 4a. Moderate suspicion of malignancy (10%–50%) requires careful correlation between pathological and imaging findings. If pathology shows typical benign lesions such as fibroadenoma, fat necrosis, or granulomatous disease, routine follow-up is appropriate; however, if pathology reveals papilloma or atypical hyperplasia, further excisional biopsy is needed—this is classified as BI-RADS 4b. High suspicion of malignancy but not meeting classic criteria for category 5 (malignancy risk 50%–95%) includes ill-defined, irregular-shaped solid masses or newly developed clustered microcalcifications. For cases with benign pathology results, consultation with a pathologist is recommended for further evaluation—this is classified as BI-RADS 4c.

6. BI-RADS Category 5

This category indicates a high probability of malignancy (≥95%), typically presenting as a high-density mass with irregular spiculated margins, segmental or linear distribution of fine linear or branching calcifications, or an irregular spiculated mass accompanied by pleomorphic calcifications. Active treatment should be initiated, including percutaneous biopsy or surgical intervention. Patients may follow medical advice to use medications such as Rupixiao or Xiaoyao Pills.

7. BI-RADS Category 6

This category applies when malignancy has been confirmed by pathological biopsy. Patients should undergo surgery as directed by their physician.

If patients experience any discomfort or symptoms, they are advised to seek timely medical evaluation to avoid delays in diagnosis and treatment.