Post-Thaw Sperm Recovery Rates; A Retrospective Study

Abstract

Background: Cryopreservation is currently the only fertility preservation option available to patients undergoing gonadotoxic treatment. Much research in the field focusses on techniques, media and equipment employed to cryopreserve cells, and demonstrating cell viability after using such. Comparatively, there is a death of information available on the procedures and equipment used to thaw cryopreserved cells, or estimates for post-thaw recovery. Aim: This is a retrospective study assessing semen parameters in post-thawed specimen from patients who attended the Royal Women’s Hospital Andrology Unit for sperm cryopreservation prior to gonadotoxic or other treatments. The study aims to examine the relationship between sperm cryopreservation technique, media and period of storage with post-thaw sperm parameters. Method: Patients with written consent to discard their stored semen were selected for inclusion in the study (n=59); samples with sperm concentration [Formula: see text]1 million/ml prior to freezing (n=11) were excluded. Semen samples were thawed accordingly: 5 minutes at room temperature followed by incubation at 37[Formula: see text]C for sperm straws; vials were transferred directly to a mixer incubator at 37[Formula: see text]C. All samples were immediately assessed for sperm concentration and motility. Recovery rates were calculated and data were analysed using SPSS (IBM, USA) version 25. Results: Progressive motility recovery was 32.4% ± 20.6. Patients were divided into groups according to period of storage, and showed no significant differences for recovery of motility and concentration (p=0.44, 0.96, respectively). Furthermore, progressive motility recovery rates were not significantly different between freezing techniques (p=0.116) and media (p=0.099). Conclusion: Data from this study are preliminary and further study is warranted to fully extrapolate the relationship between sperm cryopreservation protocols and period of storage on recovery rates. The lack of relationship between these factors exhibited in the data could suggest that research and development in thaw technologies may be more pertinent to improving sperm recovery rates.