Embryology and clinical outcomes after sperm preparation using microfluidic sperm sorting versus density gradient centrifugation

This retrospective study aims to compare laboratory and clinical outcomes of a microfluidic sperm sorting device (ZyMōt) versus a standard density gradient centrifugation (DGC) technique in ICSI cycles using autologous or donor oocytes. A total of 1,091 cycles utilizing ZyMōt and 1,176 cycles employing DGC method were included to investigate fertilization rates, blastocyst developmental rates, embryo euploidy, clinical pregnancy/live birth rates (CPR/LBR) after single embryo transfer. The ZyMōt group yielded lower DNA fragmentation and higher motility in spermatozoa compared to DGC method. Fertilization was increased (81.0% vs.78.7%; P =0.003), and the proportion of day 5 blastocysts was significantly greater using ZyMōt than the DGC method (25.6 % vs. 18.3.1%; P <0.001). The hierarchical multivariate regression models revealed that ZyMōt sperm processing contributed significantly to increased blastulation rates than the DGC method ß = 0.11, P<0.001), after adjusting for female age, male age, and infertility diagnosis. Sperm processed by ZyMōt did not enhance blastocyst euploidy rates in all stratified ages (20-40 years old). However, the cumulative CPR per retrieval using euploid embryos were noticeably higher in ZyMōt versus DGC cohorts in both oocyte donor (82.0% and 59.6%; P= 0.0042) and non-donor (73.6% and 64.5%; P = 0.0152) groups. Similarly, LBR in ZyMōt were improved significantly in both donor and non-donor groups (68.0% versus 49.7%; P= 0.0252, and 62.6% versus 52.3%; P = 0.0099, respectively). Our findings demonstrate that ZyMōt offers several advantages over the conventional DGC approach, resulting in enhanced fertilization rates, significantly increased blastocyst developmental potential and improved clinical outcomes.