Abstract
PURPOSE: Can sperm selection through cumulus cells improve embryo quality compared to conventional methods, and is its effectiveness influenced by parental age? METHODS: This prospective clinical trial included 99 ICSI cycles from 95 couples. Sibling oocytes were randomly allocated at the oocyte level to either the study group (cumulus cell-mediated sperm selection after conventional density gradients centrifugation (DGC), 554 oocytes) or the control group (only sperm selection by DGC, 543 oocytes), using a dish designed to facilitate sperm interaction with cumulus cells. The inclusion criteria for this study were patients using their own oocytes, with a medical indication for ICSI, who had at least 6 mature oocytes (MII) in that cycle. For semen samples, inclusion required the ability to adjust the concentration to 10 million/mL. Exclusion criteria included the use of vitrified oocytes, donated oocytes, and semen samples obtained by testicular biopsy or aspiration. Embryo quality was assessed at the blastocyst stage on day 5 according to ASEBIR. A subanalysis evaluated the influence of parental age on outcomes. RESULTS: The study group showed a significantly higher proportion of good-quality day-5 blastocysts compared to controls (55.2% vs. 45.3%, p = 0.028). No statistically significant differences were observed in overall blastocyst formation or pregnancy rates, although favourable trends were noted. In an age-stratified analysis, a significant improvement in day-5 blastocyst quality among evaluable blastocysts was observed in women aged 40-45 (51.4% vs. 30.4%, p = 0.017), with a non-significant trend toward improved outcomes in men aged 40-53 (44.7% vs. 32.6%, p = 0.083). No differences were seen in younger age groups. CONCLUSION: Cumulus cell-mediated sperm selection after DGC using a specialized Oosafe® ICSI Dish with Sperm Selection Channels was associated with an increased proportion of good-quality day 5 blastocysts compared with conventional sperm preparation. While clinical outcomes did not differ significantly, these findings suggest a potential benefit in specific ART subpopulations, particularly those of advanced maternal age. Further adequately powered studies are required to confirm these observations and to determine their impact on clinical outcomes.