Endometriosis (“endometriosis”) seriously affects the health and quality of life of young and middle-aged women. Recent studies have found that endometriosis is the cause of about 30% of infertility cases. The relationship between endometriosis and infertility When the endometrium growing in the uterine cavity grows in a part of the uterus other than the mucous membrane covering the uterine cavity, it is called endometriosis (referred to as “endometriosis”). The endometrium is often located in the pelvic peritoneum, ovaries, uterosacral ligament, and caesarean section scar, mainly in women of childbearing age. Endometriosis is a very common disease in gynecological reproduction, with an incidence of about 15%. The main effects on women are pain and infertility. A woman of childbearing age with a history of progressive dysmenorrhea or/and infertility and a tender hard nodule in the pelvis or an inactive cystic mass next to the uterus on gynecologic examination can be initially diagnosed with endometriosis. Ultrasound and MRI are available for the examination of patients with endometriosis cysts. Serum cancer antigen 125 (CA125) and cancer antigen 199 (CA199) are often mildly elevated in patients with endometriosis. Endometriosis seriously affects the health and quality of life of young and middle-aged women. 30% of patients are associated with varying degrees of infertility and 50% have dysmenorrhea and lower abdominal pain, which can also be without any clinical manifestations. In contrast, about 30% of infertility patients have endometriosis as the cause. In addition, patients often experience recurrent miscarriages. The relationship between endometriosis and infertility can be explained by two thirds: 1. One third of patients with endometriosis have infertility problems; 2. Endometriosis can account for up to about 30% of the causes of infertility, i.e. one third of infertile patients have endometriosis problems. The two are inseparable. Endometriosis affects infertility in several ways. It affects ovulation and corpus luteum function; causes pelvic adhesions, distortion and obstruction of the fallopian tubes; has toxic effects on spermatozoa and embryos; and alters the immune function of the body and the environment of the uterine cavity, which is not conducive to embryo implantation. Principles of treatment for endometriosis combined with infertility The principles of treatment for endometriosis combined with infertility are early diagnosis and early treatment. Laparoscopy is the gold standard for the diagnosis of pelvic endometriosis. It is generally believed that laparoscopic surgery should be performed first for primary ectopic ovarian cysts larger than 4 cm (also known as chocolate cysts, or “coeliac cysts”) to reduce the risk of infection and improve the conditions for egg retrieval, followed by treatment to assist pregnancy. In addition to the special location and difficulty of surgery, ectopic disease is also characterized by a tendency to recur, with an annual recurrence rate of up to 10%. Ovarian coeliacs are characterized by severe adhesions to the surrounding area after debulking. In almost all ovarian cyst removal surgeries, the one that has the greatest impact on ovarian function is the coeliac. It is impossible to regenerate a woman’s follicles, the reserve of which is already determined at birth. After surgery for coeliacs, ovarian function can decline prematurely, and in severe cases even cause premature failure, even if there is no premature failure. If the patient needs assisted conception techniques, her fertility will be significantly reduced. Recurrence after surgery is currently a big clinical problem. Contraceptive pills are more economical drugs. Patients who do not have fertility requirements in the short term after surgery can take oral contraceptives for a long time, not to prevent pregnancy, but to have a suppressive effect on the disease and to avoid recurrence of ectopic disease. If the pill is discontinued at the time of fertility, assisted conception or natural conception is possible. If, unfortunately, recurrent endometriosis has already occurred and there are also problems with infertility, the patient is not usually advised to undergo further surgery unless there are very severe painful symptoms and the lesion can be removed, otherwise the patient may be advised to complete the fertility requirement first. If further surgery is performed, it will be another blow to the ovaries, making them function even worse. The patient can choose a suitable method of fertility assistance, such as some of the extra-long reduction and down regulation protocols of IVF, or ovulation promotion first, egg retrieval, and whole embryo freezing. If there is a very severe adenomyoma, it may be possible to get better results by first treating it with down-regulation drugs for the pituitary gland and then transferring the embryos after a few months. The cause of ectopic disease is unclear and there are many different reasons for infertility, some suggesting that it affects the endometrial tolerance, others that it affects the quality of the eggs, etc. There is still a lot to be developed and explored, especially in recurrent coeliac disease, which is a difficult subject in fertility assistance. Patients who have had one surgery and have poor ovarian function compared to the rest of the population, as well as the growth of new coeliacs, also have an impact on the conduct of IVF, such as the tendency of infection during egg retrieval, the decrease in the number of eggs obtained, the impact on egg quality, and the poor quality of embryos, etc. These are the directions we need to research, explore and develop in the future. Prepare for pregnancy as soon as possible after surgery In young and mildly ill patients, it is recommended to prepare for pregnancy as soon as possible after surgery. You can have intercourse every three days or ultrasound monitoring of ovulation to guide the timing of intercourse. If you have not conceived after 6-12 months of trying, it is recommended to seek help from a fertility doctor. For women older than 35 years old, or for patients with severe disease, it is recommended to consult a fertility doctor directly to decide which pregnancy assistance technique to use to improve the pregnancy rate based on the male partner’s semen status and the female partner’s fallopian tube status. For example, intrauterine insemination (IUI) or in vitro fertilization-embryo transfer (IVF-ET), commonly known as “in vitro fertilization”. IVF-ET is recommended for patients who have recurrence of coeliac disease after coeliac surgery, which has a higher success rate than repeated surgeries. For young women who do not intend to get pregnant, long-term use of contraceptive pills is recommended to delay recurrence if there are no contraindications.