Treatment of severe male infertility by micromanipulation-assisted fertilization: an update

In the past 5-10 years the evolution of micromanipulation-assisted fertilization for the treatment of severe male infertility was marked by the introduction of new technical support, refinement of diagnostic methods for the evaluation of sperm developmental potential, and development of new treatment regimens for the newly discovered abnormalities. The new technical support involves the use of non-contact laser technology to assist micromanipulation for fertilization, the evolution of polarized microscopy-based optical systems to non-invasively detect the position of the meiotic spindle in living human oocytes, and the development of high-magnification optical systems for a better morphological selection of spermatozoa to be used for fertilization. Diagnostic approaches were enriched by commercial availability of kits for the analysis of sperm DNA integrity, leading to the definition of sperm nuclear DNA damage as a distinct cause of male infertility, and by the development of tests, based on heterologous ICSI, for detection of sperm failure to activate oocytes. Several treatment options for these conditions have been proposed and are currently being tested in larger-scale trials. Some technical improvement was also achieved in the field of in vitro maturation of germ cells from men with in vivo maturation arrest, but only a modest clinical improvement resulted from their application. As to the risk for the offspring, recent data are rather reassuring. Except for the risk of transmission of genetically based infertility, no straightforward evidence for a health risk derived from these techniques has been provided. Nevertheless, caution is necessary, particularly concerning the eventual increase in genomic-imprinting abnormalities.