Endometriosis

Endometriosis is a medical condition in which the endometrial tissue (i.e the lining of the womb which sheds off with every cycle at menstruation) is found in other places outside the uterus, like on the pelvic wall, the ovaries, and the bowel (the intestines). Endometriosis most commonly causes severe menstrual pain (dysmenorrhoea), and is often underdiagnosed, because of a wrong assumption that it is normal for periods to be painful.

It is not yet very clear why the endometrium is found outside the uterus in endometriosis, but there are a few likely reasons. When the endometrium is being shed during a period, it is possible that while the blood flows out through the vagina, some of it flows backwards through the tubes and ends up in the pelvic area, from where it can attach to the pelvic walls, organs, and even the bowel. (retrograde menstruation). Another possible reason is that the cells from the endometrium can be carried from the uterus to other parts of the body through the lymphatic or blood vessels. It has been shown that after one has any surgery involving the uterus (like a myomectomy or a Caesarean section), endometrial cells can be carried to the site of the skin incision and thus endometriosis develops on the surgical scar.

Endometrial tissue that is found outside the uterus is influenced by the female hormones, the same as inside the uterus. So, the tissue thickens during the cycle and is shed when menstruation begins. It is unable to flow out, and thus remains there and irritates the surrounding areas. This can cause scar tissue (called adhesions) to form, and make the organs stick to each other or stick to the walls of the abdomen and the pelvis. In the ovaries, endometriosis can cause a type of ovarian cyst called an endometrioma, which contains a thick, dark coloured fluid.