Possible predictive factors for ICSI? Molecular biology techniques in combination with therapeutic testicular biopsies.

Applying intracytoplasmic sperm injection (ICSI), the selection of an unsuccessful spermatozoon results in great emotional consequences for the couple. Therefore, there is a need for a prognostic parameter to estimate their chances for successful fertility treatment. This review summarizes both the main reasons for spermatogenic impairment, and possible predictive factors for successful sperm retrieval applying testicular sperm extraction and outcome of ICSI. While basic sperm parameters, aetiology and type of spermatozoa, and serum follicle-stimulating hormone and inhibin levels have been shown to be unrelated to the outcome of ICSI, Y-chromosome microdeletions are known to have a negative influence on the fertilizing capacity of spermatozoa. Recently, a significant correlation has been reported between the protamine-1 to protamine-2 mRNA ratio in haploid spermatids of testicular biopsies and the ability of spermatozoa for successful fertilization of an oocyte. In future, both the outstanding role of the haploid spermatids and the involvement of molecular biological techniques will improve the role of therapeutic testicular biopsies.