The two main reasons for delayed menstruation are: first, pregnancy-related problems need to be ruled out, and second, possible endocrine problems. If the patient has regular menstruation and a normal sex life, and there is a history of menopause, it is recommended to check the blood or urine for HCG. However, even if the result is positive, the final determination of intrauterine pregnancy requires an obstetrical and gynecological ultrasound. In addition, if the patient is not pregnant, an obstetrical and gynecological ultrasound should be performed, mainly to see the thickness of the endometrium. If the endometrium is thick, a progesterone withdrawal test is recommended. A positive progesterone withdrawal test indicates that the estrogen level in the body is within the normal range, and the reason for not having a period may be related to the lack of ovulation, which is an endocrine problem.