Pilot Clinical Evaluation of an Automatic Horizontal Sperm Swim-Out Method for Semen Preparation
Acosta Gomez et al., American Society for Reproductive Medicine (ASRM) 2025 Scientific Congress & Expo
Objective
To evaluate the efficiency of automated horizontal sperm swim-out (HSO) for sperm preparation for intracytoplasmic sperm injection (ICSI) compared to conventional centrifugation-based methods.
Materials and Methods
Horizontal swim-out selectively isolates motile spermatozoa by leveraging their ability to swim across a network of microchannels connecting media droplets under oil, with motile sperm accumulating in designated collection droplets. Following in-house development and validation of an automated HSO system, a pilot clinical study (Sep 2023-Apr 2024) was conducted (ClinicalTrials.gov NCT06074835) with six consenting couples undergoing ICSI treatment. Severe male factor infertility cases (volume <1.5ml, count <10M/ml, progressive motility <20%, normal forms <1%) were excluded. Using a parallel-assignment design, sibling oocytes were randomized for ICSI with fresh sperm processed by either direct automated HSO (no centrifugation) or standard density gradient separation. The automated system performed HSO by pipetting 2μ semen into four droplets and using AI to monitor migration to a final droplet. Once target concentration was reached, the system severed connections between droplets. PSA testing (detection limit 2ng/mL) confirmed complete seminal plasma removal in all cases. Oocyte preparation, ICSI, culture, and vitrification followed standard clinical protocols.
Results
Comparison between HSO and manual density centrifugation revealed no significant differences in sperm motility and concentration. A notable trend was observed in progressive motility, with automated HSO yielding 100% progressively motile sperm Vs 88.5% with manual preparation (Arcsin transformation paired T-test, P=0.06). The automated system significantly reduced processing time to 25 min, compared to 60 min for manual protocol.
Fertilization and embryo development outcomes were comparable between HSO and manual density centrifugation (Fisher's exact test). Normal fertilization rates were 69% (26/39) and 71% (17/24), respectively, in sibling oocytes (p=1.00). Blastocyst utilization rates were 70% (19/27) and 71% (12/17), respectively (p=1.00). Good-quality blastocyst formation rates (Gardner score ≥BB) were 79% and 100%, respectively (p=0.14).
Transfer of 7 single blastocysts from automated HSO led to 4 ongoing pregnancies with 3 livebirths recorded to date, representing the first babies born after sperm selection by automated HSO.
Conclusions
Automated HSO efficiently prepares normozoospermic sperm for ICSI, offering an alternative to centrifugation-based methods while delivering comparable outcomes. The system demonstrates advantages in processing time while maintaining high progressive motility. Further testing with larger cohorts and modifications for non-normozoospermic samples are needed for full validation.
Impact Statement
This automated technique may substantially improve IVF laboratory workflow efficiency and standardization by reducing processing time, disposables usage, and operator variability while maintaining equivalent clinical outcomes.
Support
Financial SUPPORT: Institutional