Nipple discharge is one of the three most common symptoms of breast disease. About 3-8% of women are found to have nipple discharge during routine breast examinations. In 12% of breast cancer cases with nipple discharge, no breast lump can be palpated, and 10% of cases have negative X-ray mammograms. In 2002, our department introduced Japanese FV-2000 microfiber breast duct endoscope to solve the difficulties of nipple overflow diagnosis and treatment, and through examination of diseased breast ducts, precancerous lesions and early breast cancer can be detected. I. Symptoms of nipple overflow (a) Sex: milk-like, watery, cheese-like, purulent, plasma-like, bloody, etc. (b) Condition: single orifice, multiple orifices; unilateral, bilateral (c) Reasons for overflow: 1. Breast diseases: such as milk retention, milk duct dilatation, inflammatory lesions of milk ducts, lobular hyperplasia, ductal epithelial atypical hyperplasia, intraductal papilloma and papillomatosis, intraductal carcinoma or breast cancer, etc. Systemic diseases The advantages and indications of mammary ductoscopy The clinical application of mammary ductoscopy is a good solution for the diagnosis of intraductal lesions, advantages: intuitive, non-invasive, accurate localization, earlier judgment, and higher diagnostic rate. Clinical application value 1, the clinical application of lactoscopy greatly improves the accuracy of nipple overflow diagnosis. 2.Lactoscopy can clarify the size, color, number and distribution of lesions, so as to guide the scope of surgical excision. Clinically, patients with plasma or hemorrhagic nipple discharge should be given high priority because most of these patients have intra-mammary duct occupying lesions that require surgery and may also be early manifestations of breast cancer. 4.Lactoscopy can save some patients with nipple overflow from surgery, and cure can be achieved through breast duct irrigation and interventional treatment. 5.Precise positioning through guide wire under the scope solves the long-standing problem of tumor localization that has plagued clinicians.