A paradigmatic shift in the care of male factor infertility: how can the recommendations for basic semen examination in the sixth edition of the WHO manual and the ISO 23162:2021 standard help?

The WHO laboratory manual for the examination and processing of human semen is a worldwide recognized source of information on reliable techniques for semen examination. Since its initial publication, aimed at providing useful data in the evaluation of male contraceptive drugs, the manual has developed to focus mainly on discovering male factors of infertility as a basis for medical assisted reproduction. The principles for basic semen examination remain mainly unchanged in the sixth edition. Some important adjustments have been made to improve efficacy, compliance with basic laboratory science and user-friendly instructions. For human sperm morphology assessment, more rationale and techniques are given for the assessment of defects in all parts of the spermatozoa. More data from men in couples with less than 1 year to initiation of pregnancy have been incorporated into the manual. The general problem, however, has been that these ranges and limits have been misinterpreted as distinct limits between fertility and infertility. This review discusses how the available distribution of data from men in couples achieving pregnancy should be interpreted. Another important aspect is the use of human sperm morphology for better understanding of functions and disorders of the male reproductive organs to increase the focus on men's reproductive health.