A, nipple depression classification: first degree of depression: part of the nipple is sunken, nipple neck exists, can be easily squeezed out, after squeezing out the nipple size is similar to normal. Second degree depression: nipple completely sunken in the areola, but the nipple can be squeezed out by hand, the nipple is smaller than normal, mostly without nipple neck; third degree depression: nipple completely buried under the areola, can not make the inverted nipple extrusion. Second, the causes of nipple indentation The general causes of nipple indentation are skin, subcutaneous tissue subsidence, nipple smooth muscle dysplasia, breast duct shortening, and partial tissue fibrosis contracture. Among them, ductal shortening and tissue fibrosis contracture are the main causes of severe nipple invagination. There are primary and secondary causes. 1, the main cause of primary nipple invagination 1.1, the nipple and areola smooth muscle dysplasia: the nipple has the opening of the milk duct, the milk duct is surrounded by smooth muscle fibers, the invaginated nipple is pulled inward around the milk duct and the bundle of muscle fibers inserted into the dermis of the nipple. The texture of these muscle bundles is significantly different from that of the milk ducts. 1.2, the milk duct itself is underdeveloped: underdeveloped milk ducts fail to ductalize and behave as striae. 1.3, lack of support tissue under the nipple support, is also the cause of nipple invagination. 1.4, genetic factors: clinical observation of the mother and her mother’s generation, the grandmother has a history of nipple indentation, the next generation of the development of nipple indentation may be higher than normal people. 2, the main causes of secondary nipple invagination 2.1, infection factors: one of the main factors in the occurrence of nipple invagination, mainly mammary ductitis with fibrosis scar contracture affects its normal development, causing nipple invagination. 2.2, breast malignant tumor: in the original breast normal women, if there is no obvious reason for nipple invagination, need to exclude the possibility of malignant tumor. 2.3, breast surgery: breast reduction plastic surgery in the application of dermatome, due to tension and scar contraction can also cause nipple invagination. 2.4, improper clothing: especially women in * breast * development period underwear is too tight, it is easy to cause nipple indentation. Inappropriate use of bras. Bras too small, too tight, used too early, can cause nipple indentation. Third, the adverse consequences of nipple indentation 1, causing nipple areola inflammation and inflammation of the mammary gland and other diseases Long-term nipple indentation, compression of the lymphatic vessels behind the areola, resulting in impaired lymphatic return, collagen tissue exudation, at the same time, due to nipple indentation, the nipple surface shedding epidermal cells and areolar secretions can not be removed in a timely manner and stimulate the nipple skin, causing inflammation of the nipple areola. Severe nipple invagination leads to mucosalization of the invaginated skin with eczema, and in some patients, bleeding and erosion, forming chronic inflammation. The ducts of the breast are connected to the invagination and the inflammation can spread retrograde infection into the breast, causing mastitis. If the nipple is not corrected in time, the inflammation is stimulated for a long time, resulting in the contraction of the breast ducts due to chronic inflammation, the nipple inversion is more serious, easily forming a vicious circle. 2, nipple inversion seriously affects breastfeeding Whether the nipple is flat, sunken, turned in, can make breastfeeding difficult after childbirth. If the nipple development is abnormal, especially if the nipple is sunken, it will inevitably affect the newborn’s catching and sucking, making it difficult or impossible to breastfeed after childbirth. At the same time, because the baby cannot catch the mother’s nipple, the milk cannot be sucked out and the newborn is prone to dehydration fever. Women with nipple invagination, often due to pregnancy breast development becomes larger and maternal milk secretion breast more swollen, nipple invagination further aggravated, the mother will give up breastfeeding because of their own deficiencies. The principle of non-surgical treatment is to make the nipple protrude by pulling it by hand or by attracting it with a breast pump, but this method is only applicable to those with flat nipples and mild invagination, and for moderate and severe nipple invagination, surgical treatment should be used. 1.1. Manipulation and pulling. The teenage period is an important time for breast development and for correcting nipple invagination. The nipples are often pulled to make the breasts stand out and to increase the support of the surrounding skin, playing a “shaping” role. This can be done several times a day. Over time, the nipples will gradually bulge outward. If you can’t pull it, you can push the skin of the breast near the nipple outward first. 1.2. It is suction therapy. After pregnancy, apply suction to the nipple several times a day, using its negative pressure to induce nipple bulging. 1.3, is to use nipple corrector is to treat flat or sunken nipples 2, surgery 2.1, surgery to preserve breast ducts This surgery is suitable for patients with mild, moderate or severe degree of sunkenness. 2.2.Surgery to cut off the breast ducts It is suitable for women who have given birth and are not considering breastfeeding in the future, or for patients with recurrent local inflammation and severe indentation deformity by scar pulling. The scar at the base of the nipple is removed during surgery, and the inflammatory mass is removed together. The ducts of the breast are completely cut off, the sunken nipple is fully released, and a tissue flap is designed to fill the tissue defect at the nipple root.