The causes of endometriosis are not yet fully understood, but the theory of endometrial implantation is recognized by most experts and scholars. The main reason is that during menstruation, endometrial glandular epithelium and stromal cells can retrograde with menstrual blood, enter the pelvic cavity through the fallopian tubes, implant on the ovaries and adjacent pelvic peritoneum, and grow and spread there, forming pelvic endometriosis. Most clinical and experimental data also support this theory, indicating that approximately 70%-90% of women experience menstrual blood retrograde. Additionally, congenital vaginal atresia can also lead to endometriosis, as well as iatrogenic endometrial implantation, such as abdominal scar implantation after cesarean section or endometriosis at the perineal incision site after childbirth. These factors may also contribute to the development of endometriosis.