Prolonged incubation of processed human spermatozoa will increase DNA fragmentation

Abstract

One of the causes of failure in ART is sperm DNA fragmentation which may be associated with long period of spermatozoa incubation at 37 °C. The objective was to evaluate the rate of sperm DNA fragmentation using the sperm chromatin dispersion (SCD) test after swim-up at different time intervals prior to use. In this prospective study, 21 normozoospermic specimens were analysed. The samples were incubated at 37 °C after preparation by direct swim-up. DNA fragmentation was assessed at different time intervals (0, 1, 2 and 3 h) using SCD test. Spermatozoa with no DNA fragmentation showed large- or medium-sized halos, and sperm cells with DNA fragmentation showed either a small halo or no halo. The rates of normal morphology and progressive motility after sperm processing were 72.33 ± 2.53% and 90 ± 1.02%, respectively. The rate of sperm DNA fragmentation was significantly higher after 2 h (8.81 ± 0.93%, P = 0.004) and 3 h (10.76 ± 0.89%, P < 0.0001) of incubation compared to 0 h (4.38 ± 0.8%). A positive correlation was found between the incubation time and sperm DNA damage (P < 0.0001). Prolonged incubation of prepared normozoospermic samples at 37 °C is associated with higher rates of sperm DNA fragmentation. Therefore, sperm samples intended for ART procedures should be used within 2 h of incubation at 37 °C.