What is Endometriosis? Endometriosis is a gynaecological condition that affects approximately one in ten women of reproductive age. This disorder occurs when endometrial tissue that typically grows inside the uterus appears in other parts of the body. This misplaced tissue most commonly grows on the fallopian tubes, ovaries, bladder, intestines, and the ligaments and muscles of the pelvis. Since this tissue acts like it would inside the uterus, it thickens, breaks down, and b