Microfluidic preparation of spermatozoa for ICSI produces similar embryo quality to density-gradient centrifugation: a pragmatic, randomized controlled trial

STUDY QUESTION Does processing of spermatozoa for IVF with ICSI by a microfluidic sperm separation device improve embryo quality compared with density-gradient centrifugation? SUMMARY ANSWER Patients randomized to microfluidic sperm preparation had similar cleavage- and blastocyst-stage embryo quality and clinical and ongoing pregnancy rates to those who underwent standard sperm processing for IVF with ICSI. WHAT IS KNOWN ALREADY Microfluidic sperm preparation can isolate spermatozoa for clinical use with minimal DNA fragmentation but with unclear impact on clinical outcomes. STUDY DESIGN, SIZE, DURATION A prospective randomized controlled trial of 386 patients planning IVF from June 2017 through September 2021 was carried out. PARTICIPANTS/MATERIALS, SETTING, METHODS One hundred and ninety-two patients were allocated to sperm processing with a microfluidic sperm separation device for ICSI, while 194 patients were allocated to clinical standard density-gradient centrifugation (control) at an academic medical centre. MAIN RESULTS AND THE ROLE OF CHANCE In an intention to treat analysis, there were no differences in high-quality cleavage-stage embryo fraction [66.0 (25.8)% control versus 68.0 (30.3) microfluidic sperm preparation, P = 0.541, absolute difference -2.0, 95% CI (-8.5, 4.5)], or high-quality blastocyst fraction [37.4 (25.4) control versus 37.4 (26.2) microfluidic sperm preparation, P = 0.985, absolute difference -0.6 95% CI (-6, 5.9)] between groups. There were no differences in the clinical pregnancy or ongoing pregnancy rates between groups. LIMITATIONS, REASONS FOR CAUTION The population studied was inclusive and did not attempt to isolate male factor infertility cases or patients with a history of elevated sperm DNA fragmentation. WIDER IMPLICATIONS OF THE FINDINGS Microfluidic sperm separation performs similarly to density-gradient centrifugation in sperm preparation for IVF in an unselected population. STUDY FUNDING/COMPETING INTEREST(S) No external funding to declare. M.P.R. is a member of the Clinical Advisory Board for ZyMot(R) Fertility, Inc. DATE OF FIRST PATIENT'S ENROLLMENT 16 June 2017.