The term “endometriosis” comes from the English translation, endometriosis, which is also known as “endometriosis” in Taiwan and other places. Let’s break it down to understand the name. The word “ectopic” means other location, abnormal location; the word “disease” means illness, disease. Therefore, “endometriosis” refers to a condition caused by an abnormal position of the endometrium. The normal location of endometrium is inside the uterine cavity, but if its location changes and appears outside the uterine cavity and causes disease, it is called endometriosis. Liu Haiyuan, Department of Gynecology, Peking Union Medical College Hospital
Where is the site of ectopic?
Let’s analyze the common abnormal locations. The endometrium is shed during menstruation and most of it flows out of the body with menstrual blood, while some of it enters the pelvic cavity through the bilateral fallopian tubes and is planted on the surface of the pelvic peritoneum, forming endometriosis foci. All organs in the pelvic abdomen are covered with a layer of peritoneum, so the endometrium that enters the pelvis can theoretically form foci of endometriosis on the surface of each organ. The most common site is the surface of the ovaries, because after ovulation the ovaries form a rupture and the defenses are reduced, making it more favorable for endometriosis to occur and grow. The next most common site is the surface of the pelvic peritoneum, either in the fossa between the uterus and rectum, on the surface of the uterus and its various ligaments, or on the surface of the intestinal canal or bladder. All of these sites are lower in the pelvic cavity, where the endometrium tends to accumulate and form lesions due to gravity in the standing position. Individual rare sites include the upper abdominal cavity such as the liver and the surface of the diaphragm.
In addition, menstrual blood flowing out through the cervix and vagina can also form foci of endometriosis if there is local trauma when passing through these areas. For example, with a lateral incision wound, endometrium (meconium) can contaminate the incision during delivery, and if the wound is not washed out, the endometrium can also grow locally to form lesions. The same can happen with endo-foci when the cervix is traumatized. In the course of physical treatment of cervical erosion (laser, freezing, lap knife, ablation, etc.) the surface mucosa of the cervix is inevitably destroyed and a trauma is formed. If menstruation occurs soon after treatment, the risk of endocervical heterogeneity is high, which is one of the reasons why we have repeatedly emphasized that operations such as cervical erosion treatment must be performed within one week of menstruation. There is also a type of endometriosis that occurs in the surgical incision, especially in the cesarean incision, and again, the opening of the uterine cavity during surgery causes exposure of the endometrium leading to implantation in the surgical incision and the formation of endometriosis in the surgical incision.