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A technique for standardization and quality control of subjective sperm motility assessments in semen analysis
C H Yeung1, T G Cooper, E Nieschlag
1Institute of Reproductive Medicine, University of Münster, Germany.
Objective:
To establish a quality control method to monitor and eventually to standardize the subjective assessment of sperm motility in conventional semen analysis.
Design:
Quality control study running over 2 years.
Setting:
University infertility clinic and andrology laboratory.
Patient(S):
Randomly chosen patients attending the clinic.
Main Outcome Measure(S):
Conventional semen analysis with sperm motility assessed by grading according to the World Health Organization (WHO) criteria and analysis of individual sperm tracks with a computer-aided sperm analysis (CASA) system. Formulas were established to identify, from the track data, the threshold velocity values for distinguishing between motility grades a and b and motility grades b and c for each technician.
Result(S):
The subjective thresholds above which technicians categorized sperm as WHO grades a and b were determined by CASA to be 61 +/- 1 and 11 +/- 1 micron/s (straight-line velocity), respectively. Agreement among three to five technicians over 2 years was reasonable (coefficient of variation < 20%), but threshold values were variable.
Conclusion(S):
Agreement within and between laboratories in the assessment of sperm motility grades could be achieved by agreeing on designated values for threshold velocities for grade a and b sperm. On the basis of such values, CASA analysis could be used to provide the expected percentages of grades a, b, and c forms for quality control samples recorded and distributed on videotapes, against which technicians could adjust their subjective assessments.