The most obvious feature of adenomyosis patients is painful menstruation, and every time they have a period, it is painful to the bone. There is a feeling of rebirth after each period. So why does adenomyosis cause menstrual pain and what are the differences between the uterus of a normal person and that of an adenomyosis patient during menstruation? On the left side of the diagram is a diagram of the uterus in a normal person without menstruation, with the muscular layer, the endometrial layer, and the uterine cavity. The right side of the diagram shows the uterus of a normal person during menstruation. When you have your period, the endometrium sheds and falls off, so what you feel is blood when you have your period, but in fact it contains a lot of endometrium. After shedding, the lining is significantly shorter than before menstruation. This very short lining is called the basal lining. After menstruation, the endometrium has to grow back. This is a normal human physiological menstrual process. The muscle layer is particularly thick, looks particularly fat, feels full, round, and has many dots in the middle. This is the uterus of a patient with adenomyosis, which not only has endometrium in its normal position, but also has endometrium in the muscle layer of the uterus, scattered like the stars in the sky. This is the uterus of a patient with adenomyosis when she is not menstruating. The normal position of the endometrium sheds and falls off, which is a normal process very smoothly. But note that the endometrium inside the myometrium is also shed, so where does it go? There is no place for it to go, it is hoarded in the muscle of the uterus, and every time you have a period, the endometrium of the myometrium is also shed once. In layman’s terms, a very small blood packet is formed inside the myometrium, and this blood packet, which bleeds out once every menstruation, cannot be eliminated from the body, but can only accumulate in the myometrium. (After each adenomyosis-conserving surgery, I often show the family when the adenomyosis lesion is removed and the lesion is cut open. This is when the family will see a little bit of black blood packet in the excised lesion). As a result, the patient will experience dysmenorrhea. Then the uterus becomes bigger and bigger like a balloon, and the patient’s pain becomes bigger and bigger. This is the pathological process of adenomyosis. This is the biggest difference between adenomyosis and normal menstruation of the uterus. The uterine preservation surgery is taken to distinguish the adenomyosis lesions from the normal muscle layer by the surgeon’s touch. The adenomyosis lesion is removed and the normal muscle tissue is preserved. The normal shape of the uterus is then restored by special sutures. The problem of dysmenorrhea is completely solved.