Continuous ultrasound monitoring of ovulation can tell when ovulation is occurring, while single vaginal monitoring is more difficult to determine when ovulation is occurring. Through the ultrasound monitoring can understand the follicle development and discharge situation, usually from the eleventh day of menstruation to start monitoring, ultrasound monitoring ovulation is a dynamic process, through a single ultrasound is not able to determine whether or not ovulation. The follicles are mature when they reach 18 to 23 millimeters in size, and several ultrasounds will show that the dominant follicle has disappeared, proving that ovulation has occurred and giving a general idea of the time of ovulation. Continuous vaginal monitoring, follicles from the development of maturity to the disappearance of the dominant follicle, during the period to arrange coitus, the woman’s chances of pregnancy is higher, the follicle fertility is the strongest is within 24 hours after ovulation. Want to accurately understand the situation of ovulation, it is recommended to go to the hospital to do the examination by a professional doctor to judge.