Direct swim-up without centrifugation is a more recommended technique for sperm preparation in conventional IVF cycles

Backgroud: The aim of this study is to investigate the most effective and maneuverable technique for sperm preparation in conventional IVF cycles. Method: A retrospective and laboratory-based study was conducted in patients who underwent their first cycle of IVF from January to December in 2016 to compare two sperm preparation techniques: direct swim-up without centrifugation (DSU) technique and density-gradient centrifugation followed by swim-up (DGC-SU) technique. A series of experiments in this study was designed to evaluate the efficiency of these two techniques which include: (i) assessment of quality and quantity of spermatozoa by comparing motility, DNA fragmentation index (DFI), acrosomal reaction (AR) and mitochondrial membrane potential (MMP) of DSU-separated sperm to DGC-SU-separated sperm, (ii) evaluation of safety of DSU technique by assessing the risks of bacterial contamination, (iii) analysis of feasibility of replacing DGC-SU with DSU technique by reviewing ART outcomes including fertilization rate, high-quality embryo rate, implantation rate, clinical pregnancy rate, take-home baby rate and abortion rate. Results: Although there were no significant differences in DFI, AR and MMP between DSU-separated sperm and DGC-SU-separated sperm, significantly higher percentage of progressive motility in DSU-separated sperm were found than that in DGC-SU-separated sperm. Moreover, there were no significant differences between DSU and DGC-SU groups on ART outcomes based on data of fertilization rate, high-quality embryo rate, implantation rate, clinical pregnancy rate, baby delivery rate and abortion rate. In addition, no bacterial contaminations were found in culture medium samples of simulating fertilization from DSU group. However, it is noticeable that DSU technique required less time and labor for sperm preparation compared with DGC-SU.