Endometriosis is a chronic disease where tissue that resembles the lining of the womb (uterus) is found elsewhere in the body. This tissue forms endometrial lesions which are most often found on the ovaries and other organs in a woman’s pelvis. In very rare cases they can be found in the lungs and even the brain.
Once implanted outside the womb, the endometrial tissue reacts to changing levels of hormones in a woman’s body during the course of her menstrual cycle, causing it to grow. This can cause inflammation and the formation of scar tissue, leading to pain.
Endometrial lesions can also lead to adhesions, which are ‘sticky’ areas of endometrial tissue that can fuse organs together. In addition, endometriosis can cause ovarian cysts (fluid-filled masses in the ovaries) which can become large and painful.