The best time to review ultrasound for endometrial thickening is on the 5th-8th day of menstruation, when the endometrium has been shed and the endometrial line is the thinnest. On the 5th-8th day of menstruation, when the menstrual flow has significantly decreased or is clean and the endometrium has been shed, the endometrium is the thinnest at this time and the endometrial line is clear. For patients suspected of having endometrial hyperplasia or endometrial polyps, it is generally recommended to use one cycle of progesterone to make the endometrium shed or to repeat the ultrasound on the 5th-8th day of the month after the menstrual period naturally comes to exclude the endometrium-related diseases. When women experience prolonged periods, dribbling of menstruation, bleeding between periods, etc., it is recommended that they visit the gynecology clinic as soon as possible to make a definitive diagnosis, and improve the hysteroscopy if necessary.