The post-ovulatory ultrasound shows that the mature follicles have disappeared and there is a certain amount of pelvic fluid, which is the amount of fluid that forms after the follicular fluid enters the pelvic cavity after ovulation. However, the post-ovulatory ultrasound alone cannot determine whether the follicle has undergone a normal process of maturation and discharge. Continuous monitoring is necessary to indicate a complete process of follicle development, maturation and discharge. Therefore, it is important to record the size of each follicle during ovulation monitoring, until it becomes a dominant mature follicle and then completely expelled from the body, such a continuous process can indicate the dynamic maturation of the follicle.