Ultrasound in gynecology is done at different times because of different diseases. If you are monitoring ovulation, you usually do an ultrasound every other day starting on the 8th or 10th day of your period, and each time you do it to see the size of the follicles and to know if they are expelled or not, this is monitoring ovulation. If it is a stomach ache or no period, it can be done anytime to see if it is because of a cyst or mass growing in the abdominopelvic cavity, adnexal area, etc. Anytime. If you want to see the thickness of the endometrium, it is usually done before menstruation. If it is too thick, abnormal hyperplasia of the endometrium may be suspected and a diagnostic scraping of the endometrium may be recommended. If there is pelvic fluid or pelvic inflammation in the previous ultrasound report, it is better for the patient to have the ultrasound after the next menstrual period, because some pelvic fluid is physiological, so it must not be done in the late menstrual period, but after the menstrual period is clean.