A centered endometrium is a description of the endometrium on ultrasound and is normal. The endometrium is a mucous membrane that covers the uterine cavity and under normal circumstances is relatively uniform and centered. If the endometrium is shifted or uneven in thickness, it may affect normal menstruation, abdominal pain and other discomforts, and in severe cases, even normal conception. Normally, under the action of estrogen and progesterone in the body, the endometrium will shed periodically, which is also known as menstruation. The endometrium is relatively thin after menstruation and will slowly thicken to a normal thickness during ovulation. The endometrium may be damaged by abortion or other reasons for uterine removal, resulting in the endometrium not being in the right place or uneven.