The endometrium is a film attached to the top of the female uterine cavity, and endometrial thickening refers to the phenomenon that this film will continue to grow and thicken, divided into two different stages, the endometrium will appear physiologically thickened before menstruation, and with the onset of menstruation the endometrium will fall off and become thinner, which is a cyclical thickening under the action of female sex hormones, which is a normal physiological phenomenon. The other phenomenon is pathological, which means that after menstruation, the endometrium will become thicker and cause a series of clinical symptoms such as increased menstrual volume, dripping and irregular menstruation. Under normal circumstances, the endometrium of women is about 3 mm after menstruation, but under the action of female sex hormones, the endometrium will continue to thicken, and will shed on its own when it reaches about 10-12 mm, that is, menstruation will come and go, and after shedding, it will only be 2-3 mm, and then thicken again, and so on and so forth. In pathological endometrial thickening, however, the thickness of the endometrium reaches 12 mm or more, and in some cases, 20 mm or more, regardless of the stage of the menstrual cycle. When a woman has endometrial thickening, it is important to determine whether it is physiological or pathological. If it is physiological, no special treatment and handling is needed, but if it is pathological, timely treatment is required.