Selecting the correct sperm(s) for microinjection during assisted reproductive technologies seems one of the key points for success.

Despite all the improvements in laboratory procedures and clinical in vitro fertilization treatments, pregnancy rates with IVF are still relatively low. Successful implantation of the embryo requires a normal shaped uterus with a proper and receptive endometrium ( inner layer of the womb ) and a genetically healthy embryo.

The relatively high rate of embryo aneuploidy ( abnormality in number of chromosomes ) seems to limit the implantation and pregnancy rates. As a woman ages, the risk for embryo aneuploidy increases. We have learned from the studies on embryos that most of the genetic abnormalities are of maternal origin, but the sperm also contributes to the genetic content of the embryo, and therefore some problems are of paternal origin. We also know that the lower the sperm count, the higher the risk for a genetic etiology of the abnormal sperm production.

In IVF, the number of the eggs from women are mostly limited. The number of the sperms from men is much higher respectively. Therefore, it is crucial to select the appropriate sperms for ICSI. There have been different sperm selection tools recommended for that aim. The biochemical and physical characteristics of mature, fully developed sperms differ from those of immature, genetically unhealthy sperm. Mature sperm display hyaluronan binding sites, and this ability has been shown to be a potentially useful tool during the selection of sperm for ICSI ( PICSI ).
Microfluidic tunnel system is another selection method used for sorting sperms which have better morphology, genetic and physiologically competent.
Men with very low motility sperms are also offered to undergo testicular sperm aspiration with fine needle since collecting the sperms directly from testickles have been found more succesful than using the ejaculate.

In our centre, for the necessary cases, we prefer using microfluidic tunnel system for sorting the sperms instead of routine selection procedures such as santrifugation and swim up or gradient. We believe that couples with previous low fertilization rates, low quality embryos and also women with low number of eggs should be considered as candidates for additional sperm selection tools.