Endometriosis refers to the appearance, growth and infiltration of endometrial tissue (glands and stroma) in the lining of the uterine cavity and other parts of the uterus, and repeated bleeding, which causes pain, infertility and nodules or masses. Endometriosis is a common gynecological disease in Chinese female patients, and its incidence has been increasing in recent years, which seriously affects the fertility and quality of life of patients. The typical clinical manifestations of endometriosis mainly include dysmenorrhea, pelvic pain and dyspareunia. Dysmenorrhea is a common symptom of endometriosis, which is secondary and persistent. The pain is most severe on the first day of menstruation and disappears completely at the end of menstruation. Pain is mainly caused by endometriosis bleeding, which irritates the inflammatory response of local tissues. Endometriosis lesions secrete prostaglandins, which cause contracture of uterine muscles and aggravate dysmenorrhea. Ovarian endometriotic cysts are the most common and easily detected type of endometriosis. Its clinical manifestations include: 1) dysmenorrhea, affecting daily activities and life; 2) chronic pelvic pain; 3) pain during or after sexual intercourse; 4) often complicated with infertility; 5) ovarian endometriotic cyst formation by imaging examination; 6) elevated CA125.

According to the guidelines for the diagnosis and treatment of endometriosis (third edition) published by Chinese Journal of Obstetrics and Gynecology in December 2021, ovarian endometriosis cysts can be divided into medical treatment and surgical treatment. The indications for drug therapy were: 1) ovarian endometriosis cyst diameter \<4cm; 2) have pelvic pain. The treatment drugs include oral contraceptives, progesterone analogues, gestrinone, gonadotropin-releasing hormone agonist (GnRHa) and traditional Chinese medicine. The indications for surgical treatment were: 1) the diameter of ovarian endometriosis cyst ≥4cm; 2) combined infertility; 3) pain medications are ineffective. In clinical practice, most patients lose the opportunity of drug treatment, or drug treatment is ineffective, and most patients need surgical treatment. Laparoscopic surgery is the first choice for surgical treatment, and cystectomy is recommended. However, surgical treatment can only remove the superficial lesions, and it is difficult to remove the deep lesions, which is easy to leave lesions. After surgery, affected by steroid hormones, the small lesions left are easy to relapse, leading to the characteristics of recurrent disease. Therefore, the recurrence rate of ovarian endometriosis cyst after conservative surgery is high, and it must be treated with drugs and long-term management after surgery.

In the postoperative drug management of ovarian endometriosis cyst, the first-line drugs are mainly progesterone analogues (dienogest), GnRH-a, dydrogesterone and so on. There is evidence that the continuous use of dienogest for 24 months after surgery can significantly reduce the recurrence rate of ovarian endometriosis cysts. Dienogest is a fourth-generation highly selective progesterone receptor agonist, which acts locally on endometriotic lesions, has no male, estrogen, glucose and mineralocorticoid activity, and does not affect metabolism. It is used in the first-line treatment of endometriosis. "In a German retrospective study, dienogest 2 mg daily for 60 months was effective in reducing endometriosis associated pelvic pain, and dienogest was well tolerated." However, ovulation was inhibited in most patients during dienogest treatment. For patients with fertility needs, menstruation returned to normal after stopping dienogest for 2 months. To pregnant element is the most common adverse drug reactions: frequent or long time of uterine bleeding (3.2%), insomnia (2.7%), acne (2.1%), nausea (2.1%), weight (2.1%), lower abdominal discomfort (1.6%), headache (1.6%), breast discomfort (1.1%), and depressed mood (1.1%). Therefore, it is not suitable to use dienogest for postoperative management in patients with ovarian endometriosis who are in urgent need of pregnancy after surgery. At present, the cost of dienogest in our country is relatively high, about 500 yuan for a box (28 tablets), and there will be a certain economic burden for ordinary patients.

"Dydrogesterone is similar in structure to conventional progesterone and has only progestogen activity without estrogen, androgen, or mineralocorticoid activity. It atrophies the ectopic endometrium, prevents the development of new endometriotic lesions, and does not inhibit normal endometrium or ovulation. The menstrual cycle is regular in the course of regular treatment with dydrogesterone, so normal pregnancy can be achieved during the treatment." An open, multi-center, post-marketing, observational clinical study in Japan showed that dydrogesterone could effectively inhibit the growth of ovarian endometriosis cysts and improve the total score of dysmenorrhea and the degree of dysmenorrhea pain. Studies have shown that long-term treatment of endometriosis with dydrogesterone after surgery for 12 months can significantly reduce endometriosis-associated pain, treat infertility, and prevent recurrence of the disease. A Japanese multi-center study showed that the incidence of adverse drug reactions of dydrogesterone was 31.8%, and the most common adverse event was uterine bleeding. Dydrogesterone endometriosis was effective, safe and clinically beneficial for patients. For patients in urgent need of pregnancy, natural pregnancy can still be achieved during postoperative medication.