Mechanisms of oligozoospermia: an oxidative stress perspective

Infertile patients presenting with poor semen concentration, motility, and morphology have significantly higher levels of reactive oxygen species (ROS). In this cross-sectional study, our goal was to: 1) determine how semen parameters such as concentration, motility, morphology, as well as ROS are altered in oligozoospermic men alone and those in combination with poor sperm concentration, motility, morphology, and compare these with three control groups; unproven donors, donors with proven fertility <2 years, and proven donors with fertility established >2 years; 2) establish the cutoff, sensitivity, specificity for ROS, and see how it compared in the three donor groups compared to the patient groups, and 3) establish the reference range for the various semen parameters in these three donor groups compared to the oligozoospermic group by generating receiver operating characteristic (ROC) curves for each parameter. Fifty-six donors and 101 infertile men were included in this study. The patient group included: oligozoospermia: n = 16; oligoasthenozoospermia (OA): n = 12; oligoteratozoospermia (OT): n = 19; oligoasthenoteratozoospermia (OAT): n = 54. The patient group was compared with the three donor groups. Proven donors who had established a pregnancy in the past or recently (<2 years) had significantly improved semen motility and morphology compared to the OAT and OT groups (p<0.001). In the OAT group, normal morphology was positively correlated with concentration and negatively with levels of ROS. Compared to the three donor groups, oligozoospermic patients in the OAT, OT, and OA groups had significantly elevated ROS levels. The cutoff for ROS in the proven donors < 2 years was significantly lower with a higher sensitivity and specificity compared to the unproven donors and donors who had not established a recent pregnancy. These results indicate a positive association between semen parameters and ROS suggesting a common underlying mechanism in these infertile patient groups.