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Abstract Study question Does microfluidic chip-sorted spermatozoa selection (MSS) improve good quality blastocyst (GQB) and embryo euploidy rates compared to density gradient centrifugation (DGC)? Summary answer The use of MSS before intracytoplasmatic sperm injection (ICSI) does not improve good quality blastocist and euploidy rates comparing to DGC. What is known already The integrity of sperm DNA plays a crucial role in embryonic development. Conventional sperm selection methods, such as DGC, may potentially damage sperm DNA due to oxidative stress generated during centrifugation. One of the recent advances in sperm selection techniques is the microfluidic chamber, which, requiring less processing time and eliminating the need for centrifugation, allows for the selection of sperm with better mobility, morphology, and reduced DNA damage. Consequently, improved GQB and euploid embryo rates, as well as enhanced reproductive outcomes, are expected. Study design, size, duration Retrospective study of 1739 blastocysts from 404 couples undergoing 544 autologous cycles of ICSI/PGT-A (preimplantation genetic testing for aneuploidies) from January 2020 to December 2022. Those patients with sperm concentration 5 × 106/mL or motility 10%, altered karyotype, women aged 43 years, uterine anomalies and thrombophilia were excluded. Besides comparing euploidy rates and blastocyst formation, reproductive outcomes were analyzed and compared. Participants/materials, setting, methods According to the sperm selection technique, two groups were established. One group underwent MSS (ZyMōt ICSI® or ZyMōt Multi®), resulting in 295 blastocysts from 96 cycles. It was compared with a control group (DGC) including 1444 blastocysts from 448 ICSI/PGT-A cycles. PGT-A was performed in day 5/6 using Next Generation Sequencing (NGS) technology. For a 95% confidence interval, statistical significance was considered at p 0.05. Chi-square analysis was used for the statistical evaluation. Main results and the role of chance Both groups were comparable in terms of demographic data, including age, sperm analysis parameters, and cycle characteristics. There were no significant differences between the DGC and MSS groups in the women’s age (mean ± SD) (37.9 ± 3.9 vs. 38 ± 3.9 years, p = 0.99) or men’s age (38.4 ± 7.1 vs. 39.8 ± 5.9 years, p = 0.11). No significant differences were found between the DGC and MSS groups in terms of GQB rate (49.3% vs. 50.7%, p = 0.55), euploidy rate (35.8% vs. 32.2%, p = 0.23), fertilization rate (69.5% vs. 69.5%, p = 0.99), clinical pregnancy rate per transfer (63% vs. 76%, p = 0.13), clinical miscarriage (9% vs. 21%, p = 0.33), and live birth rate per transfer (44% vs. 37%, p = 0.42). The results also showed a higher number of euploid embryos per initiated cycle in the DGC group (1.154) compared to the MSS group (0.989). Despite this difference, the results were not statistically significant (p 0.05). Limitations, reasons for caution The limitations of this study include the potential impact of selection bias, as it is a retrospective study in which groups were not randomly assigned. Additionally, the low number of blastocysts in the MSS group and the potential bias of DNA fragmentation, which was not evaluated in the study. Wider implications of the findings Both methods demonstrated similar effectiveness. While MSS could potentially be more effective in samples with high DNA fragmentation and they feature a user-friendly application, its major limitation lies in its challenging application with samples having a low concentration of motile sperm. Specific semen samples may need different sperm selection methods. Trial registration number Not Applicable
Valentina et al. (Mon,) studied this question.