Semen analysis remains the cornerstone of the male fertility evaluation. In 2021 the World Health Organization published the sixth edition of its laboratory manual for the examination and processing of human semen. For andrology laboratories, the update affects how tests are organised, how motility is reported and how results should be interpreted.

A new structure: basic, extended and advanced

The manual groups examinations into three levels:

• Basic examination – the standard tests every laboratory should perform, described step by step so they can be reproduced reliably.
• Extended examination – optional tests used in specific situations, such as leucocyte assessment and sperm DNA fragmentation testing.
• Advanced examination – tests mainly used in research or highly specialised settings.

Motility: rapid and slow progressive are back

The fifth edition (2010) combined all forward-moving sperm into a single progressive category. The sixth edition returns to four categories: rapid progressive, slow progressive, non-progressive and immotile. Many andrologists welcomed this, because the proportion of rapidly progressive sperm may add useful information.

Other practical changes

• A more systematic, step-by-step approach to sperm morphology assessment.
• Vitality testing is indicated when total motility is low (below 40%).
• Updated chapters on sperm preparation, cryopreservation and quality control.

Interpreting results: reference values are not cut-offs

The manual presents reference distributions from men whose partners conceived within a defined time. The lower values in these distributions describe a population; they are not strict thresholds that separate fertile from infertile men. Results should be interpreted together with the clinical history and repeated where appropriate, because semen parameters vary between samples.

Steps for laboratories updating their practice

1. Update SOPs and report templates to the four motility categories.
2. Train staff on the revised morphology and motility procedures.
3. Inform referring clinicians about changes in reporting and interpretation.
4. Strengthen internal quality control and take part in external quality assessment.

Key takeaways

• The 6th edition organises tests into basic, extended and advanced examinations.
• Motility is again reported as rapid progressive, slow progressive, non-progressive and immotile.
• Reference values describe populations and are not strict fertility cut-offs.
• Updated SOPs, staff training and quality control are essential when adopting the new edition.

Educational content only. This article does not replace institutional protocols, manufacturer instructions, clinical judgement or local regulatory requirements.

References and further reading

• World Health Organization. WHO laboratory manual for the examination and processing of human semen. 6th edition. Geneva: WHO; 2021.
• Wang C, Mbizvo M, Festin MP, Björndahl L, Toskin I, et al. Evolution of the WHO “Semen” processing manual from the first (1980) to the sixth edition (2021). Fertility and Sterility. 2022;117(2).
• Boitrelle F, Shah R, Saleh R, et al. The sixth edition of the WHO manual for human semen analysis: a critical review and SWOT analysis. Life. 2021;11(12):1368.