Background: The assessment of human sperm morphology is not devoid of methodological problems, making comparison among laboratories difficult. The main goal of this study was to assess how the experience and compliance to the recommended procedures can modulate it.
Methods: Sixty-two technicians and biologists of varying degrees of andrological experience classified the same 100 sperm in a blind study from images captured on a video microscope and projected onto a screen. David's morphology classification which distinguishes normal and abnormal sperm and calculates a Multiple Anomalies Index (MAI) was used. These sperm were also classified by two trained and experienced biologists using videotaped images to provide reference values.
Results: The inter-participant coefficient of variation was 40% for normal sperm, lower for five defects and, 12% for MAI. Experienced participants had the closest results to the reference values. Moreover, participants not routinely using the recommended methodologies, regardless of their experience level, consistently showed marked differences compared with the reference values.
Conclusions: The present data confirm the wide variability in the assessment of normal sperm and show a lower variability for several anomalies and MAI. They underscore the role that experience plays and the importance of following the recommended methodologies for relevant and comparable results.