Do studies published in two leading reproduction journals between 2011 and 2020 demonstrate that they followed WHO5 recommendations for basic semen analysis?

Abstract

Study question: Do publications that involve the interpretation of the results of a basic semen analysis, published in Human Reproduction and Fertility & Sterility between 2011 and 2020, give sufficient evidence in their methodology to demonstrate that they followed the technical methods recommended in the fifth edition of the World Health Organization (WHO) laboratory manual, entitled WHO Laboratory Manual for the Examination and Processing of Human Semen (WHO5)?

Summary answer: Evidence of methodological agreement of studies with the WHO5 recommendations was low, despite 70% of papers stating that they followed WHO5 recommendations.

What is known already: A basic semen analysis is currently an integral part of infertility investigations of the male, but method standardization in laboratories remains an issue. The different editions of the WHO manual for the basic semen analysis (WHO1-6) have attempted to address this by providing increasingly rigorous methodological protocols to reduce experimental error. However, to what extent these methods are followed by studies that involve the interpretation of the results of basic semen analysis remains unknown.

Study design, size, duration: A survey of the technical methods used to perform a basic semen analysis was conducted on studies published in two leading reproduction journals (Human Reproduction and Fertility & Sterility) between 2011 and 2020.

Participants/materials, setting, methods: The literature search was performed on the electronic databases PUBMED and MEDLINE Ovid between January 2021 and March 2021. The MeSH terms included in the search were 'sperm concentration' OR 'sperm motility' OR 'sperm morphology' OR 'sperm vitality' OR 'male fertility' AND 'human spermatozoa' NOT 'animals'. A total of 122 studies were available for analysis.

Main results and the role of chance: In total, 70% of the studies cited WHO5 in their methods section. Of the remaining studies, 10% cited the fourth edition of the WHO laboratory manual (WHO4), 7% cited both WHO4 and WHO5, 1% cited the third edition of the WHO laboratory manual (WHO3), and 12% did not cite the WHO at all. Overall methodological agreement with WHO5 recommendations was poor, with the main reason for this lack of agreement being that the research studies did not disclose specific details of the technical methods and equipment used.

Limitations, reasons for caution: In the case of studies that did not disclose any specific technical methods that they used, we did not attempt to contact these authors and so were unable to confirm the agreement between their technical methods and WHO5 recommendations.

Wider implications of the findings: Our findings suggest there is an urgent need to develop strategies to address standardization in reporting the results of a semen analysis for publication. This is particularly timely given the recent publication of WHO6 and ISO standard 23162 for the basic examination of human semen.

Study funding/competing interest(s): There was no funding for this project. C.L.R.B., as an employee of the University of Dundee, serves on the Scientific Advisory board of ExSeed Health (from October 2021, financial compensation to the University of Dundee) and is a scientific consultant for Exscientia (from September 2021, financial compensation to the University of Dundee). C.L.R.B. has previously received a fee from Cooper Surgical for lectures on scientific research methods outside the submitted work (2020) and Ferring for a lecture on male reproductive health (2021). C.L.R.B. is Editor for RBMO.

Trial registration number: N/A.

Keywords: WHO; World Health Organization; andrology; conformance; human spermatozoa; semen analysis; sperm concentration; sperm morphology; sperm motility; standardization.

Figure 1.

Flow chart of study selection according to PRISMA checklist.

Figure 2.

Overall reporting of the WHO5 recommended technical method for each semen characteristic among the 122 studies. All 122 included studies were published in Human Reproduction and Fertility & Sterility between 2011 and 2020. WHO5: the 5th edition of the World Health Organization (WHO) laboratory manual, entitled WHO Laboratory Manual for the Examination and Processing of Human Semen.

Figure 3.

Overall reporting of the WHO5 recommended technical methods for each semen characteristic in studies that also cite the Björndahl et al. (2016) checklist. WHO5: the 5th edition of the World Health Organization (WHO) laboratory manual, entitled WHO Laboratory Manual for the Examination and Processing of Human Semen.

Figure 4.

Number of WHO5 citations per year of publishing among the 122 studies. All 122 included studies were published in Human Reproduction and Fertility & Sterility between 2011 and 2020. WHO5: the 5th edition of the World Health Organization (WHO) laboratory manual, entitled WHO Laboratory Manual for the Examination and Processing of Human Semen. n = 14 studies did not mention any WHO manual.