The resazurin reduction test provides an assessment of sperm activity

OBJECTIVE: The objective of the study was to determine if reduction of the dye resazurin by semen could be correlated with the concentration of motile sperm. DESIGN: After assessment of sperm count and motility, specimens were incubated for 1 hour with resazurin (25 micrograms/mL of semen) and visual color changes indicative of dye reduction noted. SETTING: Specimens were obtained from men seeking care for infertility at one of four sites: (1) University of California, San Francisco (UCSF) In Vitro Fertilization Program; (2) UCSF Andrology Laboratory; (3) a gynecological practice in Maine; and (4) a private andrology laboratory in Southern California. PATIENTS: Individuals were self-selected by their desire to have a semen analysis in conjunction with the diagnosis or treatment of infertility. INTERVENTIONS: None. MAIN OUTCOME MEASURE: The reduction of the dye resazurin and its correlation with motile sperm density. RESULTS: When the motile sperm concentration was greater than or equal to 20 X 10(6)/mL, 86% of specimens produced a positive color change. Conversely, 86% of specimens with a motile sperm concentration of less than 20 X 10(6)/mL either did not change color or changed only over a narrow range. CONCLUSION: Reduction of resazurin offers an assessment of the active sperm in a specimen without the need to do a sperm count or evaluation of motility.