How to select the spermatozoon for intracytoplasmic sperm injection in 2015?

The selection of the individual spermatozoon in intracytoplasmic sperm injection (ICSI) is routinely performed by the observation of its motility and morphology. However, in case of severe oligoasthenozoospermia or non-obstructive azoospermia requiring the use of testicular sperm, other methods are necessary to help the embryologist making this choice. According to some authors, sperm processing before ICSI seems to limit the DNA fragmentation index, and in this way improves ICSI outcomes. Moreover, intracytoplasmic morphologically selected sperm injection is potentially a good option in some specific indications such as severe teratozoospermia, or repeated ICSI failures. Other methods based on sperm structure, as sperm head birefringence observation, or based on its function, like the hyaluronic acid or zona pellucida binding capacity, could be of interest, but still need to be evaluated. Finally, in case of akinetozoospermia, the use of functional tests, such as pentoxifylline test, HOS-test, or to a lesser extent laser touch, makes the selection of viable spermatozoa easier. Nevertheless, studies on larger series have to be conducted to evaluate and precise the interest of each of these methods and their indications, before considering an application on larger scale.