I. Introduction of mammography instruments Mammography is mainly composed of cold light source, image monitor, image recorder, optical fiber and lacrimal sac probe. There are three main types of light-guiding fibers for mammography, namely 0.9mm, 0.75mm and 0.55mm outer diameter, which can be used for diagnosis and treatment. The commonly used one is 0.75mm optical fiber. Second, the examination method 1, our hospital lactoscopy operation method for the water injection method, with the tear sac probe from fine to coarse step by step expansion of the overflowing milk duct opening, using the outer diameter of 0.75mm fiber inserted 5 to 10mm when suspended, can see the lumen of the milk duct after the injection of saline containing 1% lidocaine expanded milk duct, maintain a certain pressure, can be smoothly put into the endoscope. The lumen of the milk duct is observed on the surveillance screen while slowly inserted. 2.The lactoscope mainly observes the degree of lumen expansion, smoothness of the duct wall, the presence of flocculent material, the presence of neoplasm and its morphology and color, and the presence of bleeding. 3, the examination can be marked in the skin of the breast through the light to locate, especially at the same time to determine the distance from the opening of the duct to the site of the lesion, which is conducive to the localization of the lesion and prevent blind surgery. Also people put in the wire for positioning. The lactoscopy process can be photographed and video recorded to keep records. 4. Drain the saline from the milk ducts after the examination, and prohibit bathing on the same day. Complications 1. Rupture of the milk duct Rupture of the milk duct is related to damage to the wall of the milk duct caused by rough operation and excessive pressure in the lumen of the milk duct. The clinical manifestation is subcutaneous emphysema at the ruptured duct with a feeling of snow grip. The ductal lumen disappears on lactoscopy, showing yellow fatty tissue. When this condition occurs, no special treatment is required. Prevention is to operate gently and not to apply excessive pressure during water injection. 2. Local infection is often caused by showering the night after the ductoscopy and is manifested by tissue inflammation in the nipple and the corresponding area of the examined duct. Antibiotics are available to control the infection. Prevention is to prohibit bathing that night. D. Precautions for ductoscopy 1. Avoid forming a false tract during ductoscopy; 2. Do not miss examining each branch of the milk ducts during ductoscopy to avoid missing lesions; 3. Ductoscopy can only observe the internal situation of the milk ducts, and the extra-ductal situation needs to be evaluated by mammography or ultrasonography; 4. The ability of ductoscopy to look directly at the terminal ducts is limited by the size of the outer diameter of the fiber and the complexity of the branching pattern of the milk ducts, and these places are exactly where precancerous lesions and breast cancer originate. Milk duct lavage fluid can be collected for cytological examination or TCT to make up for the deficiency of ductoscopy.