A technique for standardization and quality control of subjective sperm motility assessments in semen analysis

Abstract

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 μm/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.