Human sperm morphology assessment since 2010: experience of an Australian external quality assurance programme

Research Question Which classification criteria of sperm normality were used after the publication of the WHO 5th Edition manual (WHO5), and how did the laboratories perform? Design Semen samples were sent to enrolled laboratories over a 10-year period for the determination of the proportion of sperm with normal morphology. The coefficient of variation (CV) was used to indicate the level of precision between laboratories. Results Prior to the publication of WHO5, there were at least 6 different classification criteria in use. After 2010, WHO5 was quickly adopted, with 50% of laboratories using WHO5 criteria after the first 2 years, rising to 93.7% after 10 years. Reported normal forms by WHO3 and WHO4 users remained consistent, however the morphology results for each distribution declined significantly over time for WHO5 users, suggesting laboratories were becoming more strict in their identification of normal sperm. The precision of WHO5 users improved over time as shown by a steady decline in the CVs. Conclusions Whilst the introduction of WHO5 resulted in the effective adoption of its morphology classification system with laboratories showing improved between-laboratory variation over time, the identification of normal forms by WHO5 users over time was inconsistent, as laboratories became more strict. Given the reduction in reported normal forms by WHO5 users, it appears that increased training of laboratory personnel or the consideration of validated objective automated analysers in the assessment of sperm morphology would seem warranted.