The most accurate method to monitor ovulation is the vaginal ultrasound method, which can not only measure whether there are dominant follicles in both ovaries, but also the size of the dominant follicles and the thickness of the endometrium, etc. You can observe which side of the ovary is ovulating by doing ultrasound. “. Also monitoring follicles with ultrasound is best done with a regular doctor. When a doctor observes a dominant follicle from a certain angle, it is better to monitor the development of this follicle from the same angle next time, “Different medical institutions and different doctors may have differences in their judgment.” Although ultrasound monitoring of eggs is currently the most accurate method, ovulation is only one of the elements of successful conception, even if the eggs are monitored to be mature and about to be expelled, there is no guarantee that the seeds will be sown at that time. From a medical point of view, there are three types of women who need to be monitored by ultrasound for ovulation. The first is women with endocrine disorders, the most common of which are patients with polycystic ovary syndrome. In this case, doctors will usually promote ovulation through medication and then monitor ovulation with ultrasound. The second type is women with immune infertility, such as women with very high anti-sperm antibodies. After medication, it is best for such women to use condoms at ordinary times and then monitor ovulation with ultrasound and conceive on the days of ovulation. The third type is a couple who wants to have children but has been unable to conceive, and needs ultrasound ovulation testing to assess the woman’s condition for pregnancy. In addition, women who suffer from menstrual disorders and irregular periods because of irregular ovulation can also use ultrasound to monitor the development of their eggs. “In general, for normal menstrual cycles (28-30 days), the development of follicles should be monitored by ultrasound from the 8th to 10th day after the start of menstruation, usually three times in a row, mostly one every other day or one a day, in order to observe follicle development and expulsion”.