Dysmenorrhea is medically classified into two types: primary dysmenorrhea and secondary dysmenorrhea. Primary dysmenorrhea occurs in association with mental factors, physical factors and spasmodic contractions of the uterus. In primary dysmenorrhea, there is no obvious organic lesion of the reproductive organs, but only a certain relationship with the structure of excessive tilting and flexion of the uterus, etc. Secondary dysmenorrhea is caused by lesions in the reproductive organs. So, which reproductive organ disorders are associated with secondary dysmenorrhea? The most common cause of secondary dysmenorrhea is due to endometriosis and adenomyosis. Endometriosis and adenomyosis are discussed below: Endometriosis The term endometriosis refers to endometrial ectopic disease (hereafter referred to as endometriosis) when the endometrial tissue is free from the uterine cavity and appears outside the body of the uterus. The most common sites of ectopic endometriosis are the pelvic organs (including the ligaments in the pelvis and the vaginal wall, with the ovaries being the most common site of implantation) and the peritoneum. It can also be found in other parts of the body, such as the bladder, ureters, kidneys, lungs, pleura, breast, lymph nodes, and even the abdominal wall scars and umbilicus after obstetrical and gynecological surgery. The incidence of the disease has been increasing year by year, becoming one of the most common gynecological diseases nowadays. It has been shown that 3-10% of women of childbearing age suffer from this disease and 25-35% of infertility patients have endometriosis. 20-90% of patients with chronic pelvic pain and 40-60% of patients with dysmenorrhea are associated with this disease. Endometriosis is usually seen only in young and middle-aged women. After menopause or because of surgical removal of both ovaries, the ectopic endometrial tissue can gradually shrink and be absorbed. Pregnancy or suppression of ovarian function with sex hormones can temporarily stop the progression of the disease. The most common symptom of endometriosis is dysmenorrhea, and this dysmenorrhea is mostly progressive with the aggravation of the local lesion, or even worsens to the point of occasional lower abdominal pain, painful intercourse and infertility in addition to pain during menstruation. If the formed endometriotic cysts twist or rupture, severe abdominal pain can occur suddenly and be life-threatening. Any young or middle-aged woman who has dysmenorrhea and this dysmenorrhea gradually and significantly worsens with each menstrual period or has a history of dysmenorrhea and infertility should promptly go to the hospital to see a doctor to determine if she has endometriosis. Adenomyosis When the endometrial glands and interstitial tissue invade the myometrium, the myometrium thickens and is called adenomyosis. Adenomyosis occurs mostly in menstruating mothers over 40 years of age, and about half of the patients have a combination of fibroids and more than 25% have a combination of endometriosis. In the last 20 years or so, with the increased use of abortion, adenomyosis, which originally occurred only in menstruating women over 40 years of age, has gradually “rejuvenated” and is now found to be increasing in young women in their 20s. The main symptoms of adenomyosis are: dysmenorrhea, a progressive increase in menstrual flow, a gradual increase in the volume of menstruation and a prolongation of the menstrual period. The dysmenorrhea often starts before the menstrual flow and does not stop until after the menstruation clears, which is very painful for the patient. If the uterus is significantly enlarged, the patient can find a hard, solid mass in the lower abdomen on her own when lying down, which is the enlarged uterus. However, 30% of patients have no symptoms and are only detected by ultrasound at the time of infertility consultation. Dysmenorrhea, especially secondary dysmenorrhea, is caused by lesions in the reproductive organs. Among them, endometriosis and adenomyosis are the causes of infertility. Endometriosis has been treated with more effective drugs and should be cured by early treatment to avoid causing infertility. There are very few medications available for the effective treatment of adenomyosis, only the aggravation of adenomyosis can be controlled during the medication. Women who are infertile because of adenomyosis have a very low chance of getting pregnant after having to treat adenomyosis. Therefore, mild cases of adenomyosis should be treated as early as possible and pregnancy should occur as soon as possible after treatment.