Who follows WHO?

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Who follows WHO?


Steven Alexander Gellatly, Ph.D.

Division of Systems Medicine
School of Medicine, Ninewells Hospital and Medical School
University of Dundee


On the 15th of September 1835 the HMS Beagle arrived in the Galapagos Islands carrying, among others, Charles Darwin. Also on board, was a copy of Werners book entitled Nomenclature of Colours, which Darwin used to describe colours in nature during his epic voyage (Syme, 1814). This book details a standardized system for the naming of colours, allowing naturalists (including Darwin) to accurately report the particular shade, tint or degree of a colour with limited uncertainty.

Today, if an andrologist were to make a similar journey they would likely be accompanied by the 6th edition of the WHO manual for The Examination and Processing of Human Semen (WHO, 2021). Let’s for a second imagine ways in which the andrologist might use their trusted travelling companion: (1) Like Darwin with his copy of Werner, they might read it and apply its principles; (2) they might not read it and therefore not be able to apply its principles; (3) they might read it but not fully demonstrate that they applied its principles or (4) they might read it but incorrectly apply its principles. Two recent publications (Vasconcelos et al., 2022 and Bjorndahl et al., 2022) unfortunately suggest that all the above options are present in andrology today and that the option the andrologist chooses (or the researcher performing the semen analysis in the case of these two papers) is a crucial one. Vasconcelos et al., 2022 surveyed studies published between 2011 and 2020 in Human Reproduction and Fertility & Sterility and found that although most studies cited that they followed WHO5 recommendations (the most up to date edition when the studies were published), most did not fully demonstrate they did so, akin to Option 3 above. Bjorndahl et al., 2022 is a plea by 86 authors to the scientific community involved in Andrology and Reproductive Medicine that performing a non-standardized semen analysis is likely to produce unreliable results with little clinical or research utility. Furthermore, they urged peer-reviewed journals to take further steps to encourage studies to be transparent when reporting the technical methods used to perform a semen analysis.

Clearly there is an issue with transparent research reporting, and as both studies point out, this is not unique to our discipline. For example, the Reproducibility Project: Cancer Biology project (RP: CP) (Rogers and Collings, 2021), which reported the results of a series of replication studies of key cancer biology papers, was one example that they gave. But what Vasconcelos et al., 2022 and Bjorndahl et al., 2022 did reveal is that there is something(s) that we can do about it. Both studies highlight the Bjorndahl et al., 2016 checklist, entitled ‘How to count sperm properly’, as a tool that can help authors, reviewers and editors when designing and reviewing studies involving the results of a semen analysis. Although, at present, filling out the checklist is not mandatory for a study to be published in any journal, contrasting the Cell Press Journals who have adopted the Structure, Transparent, Accessible Reporting (STAR) method (Marcus, 2016), Vasconcelos et al., 2022 found that studies who cited the Bjorndahl et al., 2016 checklist in their manuscript demonstrated a more robust semen analysis, according to the WHO recommendations. Clearly, this is promising and will be something that our journals should consider in the very near future to empower authors to share their expertise in a more transparent manner. Another take home message from Bjorndahl et al., 2022 is the value of scientific agreement in dealing with a scientific issue. Remarkably, this paper was not a plea from just a few authors, but 86 ones who collectively cover the different subspecialties of Andrology and Reproductive Medicine. This is certainly good news and provides hope that we draw on each other’s expertise to solve this issue which is unlikely to be solved single handed. In the near future, I hope we can use this growing scientific agreement to build special working groups within our professional societies on transparency in the reporting of semen analysis methods to help foster further discussion around this crucial issue. Inevitably, this will not be an easy journey to take, but if following standardized methods was good enough for Darwin then it is certainly good enough for us.



Björndahl L, Barratt CL, Mortimer D, Jouannet P. ‘How to count sperm properly’: checklist for acceptability of studies based on human semen analysis. Human Reproduction, 2016; 31: 227-232.

Bjorndahl L, et al. Standards in semen examination: publishing reproducible data based on high-quality methodology. Human Reproduction, 2022; deac189. https://doi.org/10.1093/humrep/deac189

Marcus E. A STAR is born. Cell, 2016; 166: 1059–1060

Syme, P. (1814). Werner's nomenclature of colours, with additions by P. Syme. James Ballantyne and Company.

Rodgers P, Collings A. Reproducibility in Cancer Biology: What have we learned? Elife, 2021; 10: e75830.

Vasconcelos AL, Campbell MJ, Barratt CLR, Gellatly SA. Do studies published in two leading reproduction journals between 2011 and 2020 demonstrate that they followed WHO5 recommendations for basic semen analysis? Human Reproduction, 2022; deac173, https://doi.org/10.1093/humrep/deac173

World Health Organization WHO laboratory manual for the examination and processing of human semen (6th ed.), World Health Organization, Geneva, Swtizerland (2022)

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Go to the profile of Pandiyan  Natarajan
3 months ago

Why to Follow WHO and what to follow in WHO semen analysis manual?

The introduction of WHO manual in 1980, brought in the much needed clarity to a confused Semen analysis picture and introduced standardized methods for evaluating a semen sample. However the so called Normal values mentioned in the first 4 volumes was far removed from reality. These values were based on Consensus, which unfortunately is an inappropriate way of doing science.

The numerical values given in the WHO manual - 6th edition may not be applicable to a given population. They are based on 5th percentile values in a certain fertile population. These values were based on single semen sample which as most of us know is notoriously unreliable. 

Following the Reference values given in the manual may not be suitable to all the populations. As was emphasized in the earlier manuals we need to estimate the basic semen analysis parameters and derive at the Reference values for our population.  To obtain uniformity in evaluating the semen sample, the standard methodology described in the WHO manual may be followed.

Professor Dr Pandiyan Natarajan.

Chief Consultant in Andrology and Reproductive Sciences,


Chettinad Super Speciality Hospital (Retired)

Professor Emeritus, The Tamil Nadu Dr MGR Medical University.