Establishing reference values and evaluating diagnostic utility of scrotal ultrasound for azoospermia subtypes: A...

Male infertility is a significant health issue in East Asia, affecting over 12 million men, primarily due to non-obstructive and obstructive azoospermia. Although scrotal color Doppler ultrasonography is widely used to assess male reproductive health, existing diagnostic standards derived from European populations remain unvalidated for Chinese men. This study aimed to establish population-specific reference values and evaluate the diagnostic utility of ultrasonographic parameters in differentiating azoospermia subtypes.

We enrolled 424 men aged 20-45 years, including 245 normozoospermic controls, 135 with non-obstructive azoospermia, and 44 with obstructive azoospermia from Guangdong Province, China. All participants underwent scrotal ultrasound following standardized protocols to measure testicular volume, epididymal dimensions, and hemodynamic parameters. Semen analysis and hormonal profiling were also performed.

Results showed that testicular volumes in fertile men from Guangdong Province, China were significantly smaller than European reference values. Testicular volume was inversely correlated with follicle-stimulating hormone and luteinizing hormone levels and positively correlated with sperm count and concentration, but not with motility or morphology. Men with non-obstructive azoospermia had significantly smaller testicular volumes, while those with obstructive azoospermia showed significant dilation of the epididymal caput.

This study provides the first scrotal ultrasound reference standards for men from Guangdong Province, China and suggests that a two-parameter approach based on testicular volume and epididymal caput diameter may aid in non-invasive differentiation of azoospermia subtypes, potentially reducing the need for invasive biopsies.