The thickness of the endothelium during ovulation is roughly around 5-6mm, there may be individual differences and measurement errors exist, the premenstrual period is the late secretion stage of the endothelium, the endothelial thickness can reach around 10mm. The endothelium is shed during PMS, and the thickness of the endothelium may change due to other factors, such as damage to the basal layer of the endothelium caused by a history of multiple uterine surgical operations, or adhesions in the uterine cavity, which can cause the functional layer of the endothelium to become thin, resulting in a low volume of menstruation, or even amenorrhea. If high estrogen levels, anovulation, no progesterone antagonism, abnormalities such as endothelial thickening and endothelial polypoid hyperplasia occur, symptoms such as irregular bleeding and dribbling occur. Thick or thin endothelium may cause irregular menstruation, causing abnormalities in menstrual cycle, menstrual period, menstrual flow, etc. It is necessary to pay attention to hygiene in general, avoid multiple abortions, and consult the doctor in time when there is abnormal bleeding.