If a woman’s menstrual period is about 30 days and her period clears in about a week, the thickness of the endometrium should be about 0.2-0.3cm just after the end of the period. Generally, it will not exceed 0.5cm. If it exceeds 0.5cm, the endometrium is too thick and the possibility of endometrial lesions should be considered. If the patient has a short menstrual cycle, about 22-23 days, and a long menstrual period about 7-8 days. The first three days of menstruation are relatively heavy and the last 4-5 days are very light. In this case, the patient’s endometrium may be thicker, reaching about 0.5-0.6 cm, just after the end of menstruation. This is mainly because the patient has just finished menstruation and has already entered the ovulation period, when the endometrium of the patient will proliferate significantly under the effect of estrogen, so it is relatively thicker.