A 2cm thick endometrium may also be normal. Normal endometrium changes with the menstrual cycle, the endometrium may reach 2cm before menstruation. as the menstrual cycle changes, the endometrium is peeled off, and the endometrium can reach 4mm after menstruation, so the endometrium is 2cm depending on what period of the menstruation it is. If the endometrium is 2cm before menstruation, it is normal. If the endometrium is 2cm after menstruation, it is a manifestation of abnormal thickening of the endometrium. Clinically, the thickness of the endometrium is determined according to the menstrual cycle. The endometrium is thickest before menstruation and thinnest after menstruation, so it is more accurate to judge the endometrium according to the menstrual cycle.