Endometriosis is a condition where tissue, similar to the tissue that normally grows inside the uterus, also grows outside of the uterus. The tissue inside the uterus is called “endometrium” and the tissue outside of the uterus is called “endometriosis”. The most common places where endometriosis occurs are the ovaries, the fallopian tubes, the bowel, and the areas in front, in back, and to the sides of the uterus.