The degree of inversion in clinical practice mainly refers to female nipple inversion, which is a common gynecological breast deformity. According to the depth and location of the nipple, it can be categorized into type I nipple inversion, type II nipple inversion and type III nipple inversion. 1. Type I nipple inversion: it is mild nipple inversion, which is manifested as nipple mildly sinking into the areola, nipple neck is visible, and the inverted nipple can be pulled out by hand, and the size is the same as that of normal nipple. 2. Type II nipple inversion: it is moderate nipple inversion, which shows that the nipple is completely sunk into the areola, but the complete nipple can be pulled out or squeezed out, and most of the nipple is without nipple neck, and the size of the nipple is slightly smaller than that of the normal nipple. 3. Type III nipple inversion: it is severe nipple inversion, in most cases, it is deeply buried in the areola, and it is impossible to pull out the nipple by hand or extrude the nipple by pressing. To distinguish the degree of inversion depends on the depth of the nipple into the areola. If the nipple is mildly inverted, it does not affect the normal function, so there is no need to worry too much. If the degree of inversion is serious, it is recommended to consult a doctor in time and actively cooperate with the doctor’s treatment.