Which to Choose for Sperm Sorting? Swim up Versus Density Gradient: A Sibling Oocyte Study

Abstract

Objective: The efficiency of different sperm sorting methods for retrieving higher quality sperm cells during infertility treatment has been under investigation for many years. The aim of this study was to compare the effects of two commonly used sperm sorting methods on laboratory and clinical outcomes by using sibling oocytes. Materials and Methods: 72 female patients having a total of 1075 mature oocytes and their partners were included in this study. All semen samples were divided into two aliquots and prepared either by pellet swim up or single layer centrifugation before intracytoplasmic sperm injection. Mature oocytes of each patient were split into two groups; and each group was assigned to one of the sperm sorting methods. Results and Conclusion: The main outcome measure of the study was total blastocyst development rate whereas other outcome measures (fertilization rate, blastocyst development rate, embryo quality, pregnancy and implantation rate) were also compared between the groups as the secondary outcomes. Although pellet swim-up method demonstrated a higher blastocyst yield (total blastocyst development and blastocyst utilization rate) compared to single layer centrifugation in our study, the difference did not reach a statistical significance level (p>0.05). Moreover, no significant differences were found between the groups in terms of fertilization, embryo development, embryo quality on day 2, pregnancy and implantation rates (p>0.05). Our data suggest that both methods have comparable effects in terms of blastocyst utilization and implantation rates; thus, may be used alternately according to the conditions and needs of different laboratories.