New World Health Organization reference values for semen analysis: where do we stand?

Semen analysis is of paramount importance to study potential male fertility, couple's infertility, the effects of gonadotoxic agents on spermatogenesis and as follow-up test during treatment of male infertility. Since 1987, the World Health Organization proposes the standardization of this test and its reference values based on population-based data. The latest version of the World Health Organization guidelines was published in 2010. It introduced a new methodology that produced new references values, which triggered a discussion that lies inconclusive. We revised the original World Health Organization paper focusing on methodological changes and its results, the new references values and their impact on clinical practice.