Table 1. List of key findings on ORP and male infertility in clinical studies.
| Study | Key findings |
|---|---|
| Agarwal et al. [53] (2016) | 1. ORP can be measured in semen and seminal plasma |
| 2. ORP measurements are stable up to 120 minutes | |
| 3. Negative correlation between ORP and semen concentration/total sperm count regardless of fertility status | |
| Agarwal et al. [54] (2017) | 1. Elevated levels of ORP in infertile patients compared to those of controls |
| 2. Negative correlation between ORP and semen parameters (concentration, total sperm count, motility, and morphology) in all subjects | |
| 3. ORP value of 1.36 mV/106 sperm/mL to distinguish fertile from infertile men | |
| 4. Low intraobserver and interobserver variability | |
| Agarwal and Wang [55] (2017) | 1. Elevated levels of ORP in abnormal semen parameters (of infertile patients) |
| 2. Sperm concentration and motility improves as ORP decreases | |
| 3. ORP value of 2.59 mV/106 sperm/mL best predicts oligozoospermia | |
| 4. A combination of ORP and at least 1 other abnormal semen parameter (especially concentration) is more robust in identifying OS than ORP alone | |
| Agarwal et al. [56] (Forthcoming) | 1. ORP is highly predictive of OZ and AZ samples regardless of fertility status. There is a weaker predictive value for TZ and OAT samples |
| 2. ORP is best at predicting OZ samples | |
| 3. Elevated levels of ORP in all subgroups when compared to NZ samples | |
| 4. A combination of ORP and two other abnormal semen parameters is more robust in identifying OS than ORP alone | |
| Agarwal et al. [57] (2017) | 1. Collectively and individually between the Cleveland Clinic and Doha, Qatar, there were poorer semen parameters and higher ORP values present in infertile semen samples when compared to those of healthy controls. |
| 2. No significant differences between infertile groups in both data sets except progressive motility and morphology | |
| 3. No significant differences between control groups in both data sets except morphology | |
| 4. Elevated levels of ORP in abnormal semen groups | |
| 5. ORP value of 1.42 mV/106 sperm/mL to distinguish fertile from infertile men | |
| Arafa et al. [58] (2017) | 1. ORP value of 1.38 mV/106 sperm/ml to distinguish normal from abnormal semen samples |
| 2. ORP value of 1.41 mV/106 sperm/mL to distinguish fertile from infertile men |
ORP, oxidation-reduction potential; OZ, oligozoospermic; AZ, asthenozoospermic; TZ, teratozoospermic; OAT, oligoasthenoteratozoospermic; NZ, normozoospermic.