Comparison between Sperm Preparation before Cryopreservation and Post-Thawing Sperm Preparation using Density Gradient Centrifugation in Normozoospermic Semen Samples

Abstract

Sperm cryopreservation has been considered as an efficient procedure for management of male fertility. Different freezing protocols have been developed to maximize the post freeze quality. The current study investigates the differences between sperm preparation before and after freeze. 120 Semen analysis reports from 18 sperm donors were analysed. 60 semen analysis reports were from samples that were frozen then washed (Group 1: Post-wash) while the other 60 semen analysis reports were obtained from samples that were washed then frozen (Group 2: Pre-wash). Sperm concentration and progressive motility were evaluated for each group and compared. Sperm concentration was higher in the pre-wash group compared to post-wash (33.05 ±12.9 vs 26.13 ±13.36, respectively). Progressive motility was higher in the post-wash group (82.3 ±14.9 vs 51.6 ±8.2). There was a significant decrease in sperm concentration between fresh samples and both (post- and pre-wash) results. Significant decreases in progressive motility were found in both methods. Sperm freeze using fresh semen samples and washed samples resulted in significant decrease in post freeze progressive motility. However, fresh samples had a higher post freeze recovery rate compared to washed samples (72.15% vs 56.32%). Semen preparation by density gradient centrifugation before freezing resulted in better sperm concentration, while the preparation of spermatozoa after freezing had a higher progressive motility. Therefore, sperm freezing methods should be adapted according to semen samples quality.