Endometriosis and Oxidative Stress. Do Reactive Oxygen Species Always Lead to Damages of Gametes and Embryos?

Reactive Oxygen Species (ROS) play a crucial role in the pathogenesis of many reproductive disorders, such as endometriosis on the one hand, but on the other hand they participate in different cellular proliferation processes, too. Endometriosis is an apoptotic endometrial, menstrual cells and lysed erythrocytes-induced inflammatory disease outside the uterine cavity, which activates macrophages leading to ROS production and oxidative stress. However, based on the available literature, the reproductive outcomes are still contradictory. In this study, the demographic, embryological and clinical results of 252 patients suffering from tubal infertility (control), ASRM I-II and III-IV endometriosis were analyzed. Endometriosis was associated with decreased anti-Müllerian hormone level and increased gonadotropin doses during stimulation (p<0.0001). In ASRM III-IV, reduced embryological parameters were observed, which resulted in 13.73% and 15.21% decrements in the implantation rates, 19.96% and 23.89% in the clinical pregnancy rates of patients suffering from ASRM III-IV endometriosis in comparison with control or ASRM I-II, respectively. In addition, miscarriage rates were 19.04%, 29.03% and 38.46% in control, ASRM I-II and ASRM III-IV, respectively. In our study, the supposed altered oxido-reduction environment of gametes and embryos obviously exerted negative effects on the embryological and clinical parameters, but these effects could not be observed in case of mild endometriosis with low level of stress.