Nipple discharge is the overflow of fluid from a single or multiple milk holes on the nipple when the nipple or a part of the breast is not squeezed or slightly squeezed, and is sometimes detected only because the overflow stains the underwear. Its incidence is about 10%, second only to breast pain and breast lumps, and it accounts for a significant proportion of the first symptoms of breast diseases. It is the most direct manifestation of many breast diseases and should be given high priority by doctors and women with symptoms. Clinically, nipple discharge can be divided into physiological and pathological overflow. Physiological overflow refers to lactation during pregnancy and lactation, bilateral nipple overflow caused by oral contraceptives or sedatives, and unilateral or bilateral small amounts of overflow in postmenopausal women. Pathological overflow, on the other hand, refers to natural overflow from one or more milk ducts on one or both sides during non-pregnancy lactation, which can be intermittent or continuous, ranging from a few months to several years. Pathological overflow is divided into pseudo-overflow caused by superficial nipple lesions and true overflow caused by systemic or intramammary lesions. Common systemic systemic lesions include endocrine disorders, hemophilia, purpura, etc. Local lesions in the breast are mostly intraductal papillomas, ductal dilatation, cystic hyperplasia, mastitis or abscess, breast cancer, etc., which may or may not be accompanied by breast pain and lumps. The type of overflow can be milky fluid, acne-like fluid, watery fluid, purulent fluid, plasma fluid, bloody and plasma-hemorrhagic fluid, etc.; the amount can vary from natural overflow without squeezing to only 2-3 drops of overflow with forceful squeezing. Nowadays, the examination methods for nipple overflow include smear cytology, ultrasound, mammography, CT and MRI, mammography and tumor marker examination, which have different emphasis but complement each other. If the cause of the lesion can be clinically determined after the examination, appropriate treatment, including medication and surgery, can be given according to the cause, and the prognosis is good except for breast cancer. When you find that your nipples are overflowing or your underwear is stained with overflow, do not panic. Before going to the specialized breast surgery department for the necessary examination, you should make the following preparations: 1. pay attention to the local cleanliness of the nipples after the discovery until the consultation; 2. stop squeezing your breasts and nipples for 2-3 days before the consultation to prevent the amount of overflow from being too much and the amount of residual fluid in the breast from being too little, resulting in no overflow at the time of consultation; 3. Observe the color, odor and amount of the overflow each time it occurs, so as to provide the doctor with more accurate information about the nature of the overflow and prevent the overflow from changing during the consultation and interfering with the doctor’s correct diagnosis.