The ultrasound ovulation monitoring can be done in the afternoon. Ultrasound ovulation monitoring is mainly through the vaginal ultrasound to observe the size of the follicles in both ovaries, so as to better arrange the time of coitus and enhance the success rate of couples to get pregnant, there is no strict requirement for the time, no matter whether it is in the morning or in the afternoon can be, mainly depends on the individual’s time. If the follicles are maturing, you can even monitor them in the morning and afternoon together. Ultrasound ovulation monitoring is usually detected from five days before the day of ovulation, when the follicle is more than 18mm, it will be ovulated within 24 hours, and the eggs can be kept in the body for 24 hours, because it is necessary to have intercourse in time within this time, so as to enhance the chances of pregnancy. However, every person’s situation is different, and it is recommended to arrange the time reasonably under the guidance of the doctor.