Intracytoplasmic sperm injection (ICSI) can be considered the most revolutionary in vitro insemination technique because it has efficiently allowed the treatment of male factor infertility. Although ICSI has been successfully and safely applied worldwide for almost 20 years, currently, we have no real knowledge regarding the hypothetical long-term side effects on ICSI adults, given the increased likelihood of spermatozoa with defective nuclear content fertilising the oocytes. The aim of this review article is to investigate the most recent advances of performing ICSI in the safest possible manner, thus, minimising the theoretical hazards of this procedure. To allow for substantiated recommendation which male gametes to choose for physiological ICSI an updated search was performed in Medline and Embase, from 1996 to June 2011. Recent technical advances allow operators to more or less simulate physiological conditions in the laboratory, reducing potential damage to the gametes. It seems possible to prevent fertilisation by DNA-damaged and chromosomal-unbalanced spermatozoa by selecting ICSI sperm by motility and/or maturation markers such as hyaluronic acid or other zona pellucida receptors. Furthermore, novel non-invasive imaging techniques can be valid tools for helping in the morphological selection of ICSI spermatozoa.
