Follicular monitoring during menstruation reveals an anechoic follicle, and other follicles may continue to grow, which needs to be dynamically monitored under ultrasound for its specific development. In general, after the menstrual period is clean, there will be follicle development inside the ovary, at this time the follicle is relatively small, the ultrasound performance is anechoic area, usually develops to the 14th day of the menstrual cycle will grow to 18-22mm, and then will be ruptured to discharge the egg. There are usually more follicles in a month, but the ones that develop into dominant follicles are usually one or two, while the others usually end up atretic and do not continue to grow. In addition to the absence of echo to rule out the presence of ovarian cysts, can ultrasound continuous dynamic monitoring 2-3 menstrual cycles. It is recommended to go to the hospital under the guidance of the doctor for dynamic follicle monitoring, in addition to the ovulation test paper or temperature measurement, observation of the white belt to determine the specific follicle development and ovulation.