1, the anatomical basis of nipple emergence. The central part of the breast is the nipple, and the circular area around the nipple is the areola, with darker skin coloring in this area. Each breast contains 15 to 20 bicycle spoke-like arrangement of glandular lobes, glandular lobules, and glandular lobules are composed of many glandular vesicles; between the glandular lobes, between the glandular lobes and glandular vesicles are interspersed with connective tissue. The ducts in each glandular lobule, which are connected to the alveoli, converge in the direction of the nipple to form the glandular lobe ducts, which gradually increase in size to form a pot belly and then divide into 10-15 openings on the surface of the nipple (see diagram). 2.Who will have nipple discharge? Nipple overflow accounts for about 5% to 10% of breast diseases and is one of the common symptoms of breast diseases. It is common in people aged 40 to 50 years old, and the overflow is bloody or colorless plasma-like, clear water-like, yellow, brown, milk-like, etc. It can be unilateral or bilateral. Lactation during pregnancy and lactation, nipple overflow in pre- and post-menopausal women and nipple overflow caused by nipple stimulation are physiological phenomena, and the overflow is usually clear and colorless, pale yellow and transparent or milk-like, and can occur unilaterally or bilaterally in the breast, and the overflow often appears in multiple breast holes. As maternal hormones enter the fetus through the placenta and produce lactation, the mammary glands of newborns can occasionally be seen to secrete milk, called infant milk or odd milk. Baby milk usually appears 2-4 days after birth and can last 1-3 weeks, sometimes up to 1 month. 3.Why does nipple discharge occur? Nipple discharge is divided into physiological discharge and pathological discharge. Physiological overflow is mainly seen in the middle and late stages of pregnancy, after miscarriage, several months after termination of breastfeeding and before and after menopause, or due to nipple irritation, birth control pills, stomach pills and sedative drugs. When the trigger is removed, the overflow will stop automatically and no special treatment is needed. Pathologic overflow, on the other hand, refers to non-physiologic ductal overflow, which can come from one or both breasts and can manifest as intermittent/persistent nipple overflow from one or more ducts over a period of months to years. The causes of pathologic nipple discharge are extramammary factors and disease factors of the breast itself. Extramammary factors are characterized by bilateral, porous, milk-like or clear water-like nipple discharge. Extramammary factors include pituitary tumors, hyperprolactinemia, and endocrine system disorders, which are mostly bilateral overflows. The former is commonly caused by ductal dilatation, cystic hyperplasia, etc.; the latter is often caused by intraductal papilloma, breast cancer, etc. 4.Does watery nipples indicate breast cancer? The latter is often caused by ductal papilloma or breast cancer. 5.What tests are needed for nipple discharge? (1) Ultrasound examination, however, because benign and malignant lesions in the breast ducts often exist at the same time, and malignant lesions are often regionally non-uniformly distributed, ultrasound examination cannot accurately identify the benign and malignant nature of intraductal occlusion. (2) Mammography. (3) Fiberoptic ductoscopy (FDS) is a tiny endoscope that allows direct visualization of the duct wall and lumen in patients with papillary overflow, enabling early detection of the cause of papillary overflow and accurate localization of the lesion to facilitate surgical localization biopsy. (4) Breast MRI examination has been widely carried out in the diagnosis of breast diseases, which can understand the location, size, number of breast overflow lesions, the degree of neovascularization of the lump and other information. 6.How to treat nipple discharge? Physiological nipple overflow can be left untreated. For pathological nipple overflow, the main treatment is for the cause. For swelling in the breast ducts, surgical treatment is required.