Percoll gradient centrifugation can be omitted in sperm preparation for intracytoplasmic sperm injection

Prior to intracytoplasmic sperm injection (ICSI), seminal fluid iscurrently washed out from the ejaculated semen and further sperm selectionis carried out by a discontinuous Percoll gradient. Possible deleteriouseffects from the sperm-separating substance Percoll on sperm function orembryo cleavage after in-vitro fertilization (IVF) have, to our knowledge,not yet been reported and the use of Percoll has been widely accepted inIVF. In this study, we examined whether the omission of the Percoll step inthe sperm preparation has any influence on the outcome of the ICSIprocedure. Two methods of sperm preparation for ICSI were compared in acontrolled study on sibling oocytes: washing the semen sample once,followed by a Percoll gradient centrifugation versus washing the spermsample twice without a Percoll gradient centrifugation. The meanfertilization rates were similar for the two sperm preparation methods:78.2 +/- 21.4 and 75.0 +/- 24.1% respectively of the intact oocytesdisplaying two pronuclei. Cleavage rates did not differ statisticallybetween the two groups. Whereas in both groups similar percentages ofexcellent, good and poor quality embryos were obtained, the percentage offair quality embryos was significantly higher in the group without Percoll(16.3 +/- 20.1 versus 9.1 +/- 15.7%). However, no statistical differenceswere observed in either the percentage of transferable embryos or in thepercentage of embryos actually transferred or frozen in the two groups. Inconclusion, spermatozoa from ejaculates that are washed out from theseminal fluid without any further selection can be used for ICSI withoutany adverse effect on fertilization and embryo cleavage.