Table 1.

The major changes from the 1^st to the 6^th edition of the WHO laboratory manual for the examination and processing of human semen.

Edition	Year	Pages	Major Changes
1st	1980	43	Semen: sample collection, initial examination, sperm motility, sperm density, sperm morphology (plates and stians0 Sperm cervical mucus interaction: collection of mucus, in vitro test, post-coital test
2nd	1987	67	Semen: Standard tests- includes all in the 1st edition + sperm antibody tests Optional tests – semen culture, seminal fluid biochemistry, zona free hamster oocyte penetration test, sperm migration test Criteria of normality of semen samples
3rd	1992	107	Standard test – use “strict criteria for assessment of sperm morphology Research tests -zona free hamster oocyte penetration test, human zona pellucida binding test, acrosome reaction, computer assisted sperm analysis (CASA) Sperm preparation Quality control of semen analysis
4th	1999	128	Optional tests – added hypoosmotic swelling test, multiple sperm defects index Research Test – reactive oxygen species Quality control- statistical analyses of counting errors
5th	2010	271	Most extensive and comprehensive revision of the semen manual Detailed description of each procedure Added total sperm output per ejaculate as a semen variable Sperm motility combined rapid and slow into one grade of progressive motility Sperm preparations include spermatozoa from testis and epididymis Using quality control to improve laboratory performance Added chapter on cryopreservation of spermatozoa
6th	2021	276	Step by step easy to follow procedure Basic examination = standard tests, reintroduce slow progressive motility Extended examination =optional tests included leucocyte, immature germ cells, added sperm aneuploidy, sperm genetics and DNA fragmentation Advanced examination = research tests, added membrane ion channels Emerging methods of semen analyses without a microscope Eliminated hamster zona free penetration test, human zona binding test and section on sperm-cervical interaction