The sixth edition of the WHO Laboratory Manual for the Examination and Processing of Human Semen: ensuring quality and standardization in basic examination of human ejaculates

A basic semen investigation has established principles that are necessary for ascertaining reliable and internationally comparable results. Although these principles have been present in the WHO manual since its inception, the baseline issue across most published studies and practice in reproductive medicine (in which the male is considered) is repetitive failure to adhere to these principles, thereby leading to relevant comparable data and accuracy. To address this failure, the sixth edition of the WHO manual includes revised basic methods, and a complementary formal standard of the International Standards Organization (ISO23162:2021) for basic semen examination has been published. Perhaps the most significant change in the sixth edition is the reintroduction of the four-category distinction of sperm motility, which causes additional work for laboratories in changing reporting parameters but is clinically important. Another essential change is the widened focus from mainly a prognostic tool for medically assisted reproduction to additionally raising awareness of semen examination as a measure of male reproductive functions and general male health. (Fertil Steril (R) 2022;117:246-51. (c) 2021 by American Society for Reproductive Medicine.)

Automated summary

The principles of basic semen investigation are crucial for obtaining reliable and internationally comparable results. However, many studies and practices in reproductive medicine fail to adhere to these principles, leading to a lack of comparable data and accuracy. To address this issue, the sixth edition of the WHO manual introduces revised methods and a complementary formal standard from the International Standards Organization. The new edition also reintroduces the four-category distinction of sperm motility and emphasizes the importance of semen examination for assessing male reproductive functions and overall male health.