SCA® CASA, more consistent than manual analysis

WHO Manual Analysis may be the Gold Standard for Semen Analysis but SCA CASA is more consistent than Manual analysis

During the past year I assisted with a study investigating the relationship between World Health Organization (WHO 5, 2010) manual analysis criteria of semen analysis compared to SCA® CASA analysis which involved three independent centres in three countries (USA, France and Spain). In this study sperm concentration, percentage progressive sperm motility, percentage total sperm motility and percentage normal sperm morphology were compared in each centre for each semen sample using both WHO Manual analysis and SCA® automated analysis. A protocol was designed to dictate that specific procedures be followed and also ensured that similar methods were followed for the different centres. So there was good standardization in terms of manual as well as SCA® automated CASA analysis.

The three Centres each analyzed between 50 and 69 patients each. Data was collated in a similar manner and then independently analyzed by two statisticians using a very wide battery of tests such as Bland and Altman Plots (a very good method to establish similarities of using different techniques) and ROC curves for showing that if differences exist between the two techniques.

Of great interest is that for most of these parameters there was a very high level of agreement between Manual compared to SCA analysis for most of these parameters. Sperm concentration showed the highest agreement. This was not surprising because for Manual methodology a semi-quantitative technique is used – A Neubauer Improved Haemocytometer. However, sperm concentration by SCA® took several seconds compared to manual which take several minutes.

Both the percentage progressive sperm motility and percentage normal sperm morphology also showed very good correlations between Manual compared to SCA® CASA. The results for percentage sperm motility differed more than the above between the two methods although reasonably good correlations were still evident. However, in almost all instances the coefficient of variation was always considerably larger than and often twice as big as for Manual compared to SCA® analysis. This clearly shows that Manual subjective analysis of sperm quality is much more variable than previously thought and that SCA® CASA was much more consistent.

What makes this study so significant?  SCA® CASA can be used in semen analysis in the Clinical laboratory. There is still a great deal of scepticism that in human clinical Andrology and fertility assessment, CASA is still not reliable in assessing human semen quality. This study clearly removes this bias at least in terms of Microptic SCA® but also shows that that Manual WHO sperm assessment is much more variable and open to human error and bias despite so called quality control.

I visited in the last five years Andrology laboratories in some 22 countries and can assure readers of this Blog page that manual quality control in most of these are extremely poor, leave alone basic use of the microscope and ignoring the importance of temperature control.

Where do we go from here. Currently a global programme has been lodged to establish the kinematic cut-off points for CASA and universities in Denmark, Poland, Spain and South Africa is currently involved in this. We believe that within two years CASA will be more common in the clinical setting than before.

Gerhard van der Horst