Role and significance of sperm function in men with unexplained infertility

Abstract

It is estimated that about 20 % of couples with difficulties to conceive have no identifiable infertility conditions based on the routine investigation. Such couples are categorized as having unexplained infertility (UI). Concerning the male partner, results of semen analyses are usually taken as surrogates of the fertility potential. Semen analysis, however, must go far beyond counting spermatozoa and assessing motility and morphology, as routinely performed. After ruling out female infertility factors, specialized andrology testing may assist in unraveling dysfunctions related to immunologic disorders, excessive oxidative stress, and other problems affecting spermatozoa at the cellular and subcellular levels. Recent advances in the field of genetics, proteomics, and metabolomics hold promise and some tests, including those that measure sperm chromatin integrity and reactive oxygen species (ROS), have already been added to the laboratory male infertility investigation. This chapter focuses on the traditional and novel clinically available laboratory methodologies for the investigation of the male partner of couples with UI, including antisperm antibodies (ASA), sperm fertilization defects, levels of ROS both in the sperm and seminal plasma, and sperm chromatin integrity. The identification of dysfunctions by cost-effective and accurate specialized sperm function tests helps not only to identify the cause of male infertility but also to define treatment strategies.