Patients with endometriosis may present with different clinical symptoms and at various stages of disease. Many women are not diagnosed until they decide to have a tubal ligation as a contraceptive measure. (A tubal ligation is an elective surgical sterilization procedure in which the each of the fallopian tubes are cut, tied and sealed by cauterization.) In roughly 1 out of 10 of these operations, surgeons see signs of endometriosis. Endometriosis is also often diagnosed after women have difficulty getting pregnant. About one third of women who have endometriosis are infertile, and the disease is considered 1 of 3 main causes of infertility. Endometriosis can cause infertility when the implants cause scarring in the reproductive organs.