Assessment of testicular volume: A comparison of fertile and sub-fertile West African men

Abstract

Background: While the semen analysis appears to be the cornerstone in the evaluation of testicular function, the testicular volume has long been associated with testicular function. However, racial variations in testicular volume do exist. Neither the critical minimum testicular volume that guarantees adequate function, nor the optimal testicular volume that indicates peak testicular function are also known.
Objective: To evaluate the relationship between testicular volume and function using scrotal ultrasound scan in black West African men.
Patients and methods: The study examined 236 subjects over a period of one year. The subjects comprised of 136 patients with diagnosis of male infertility, as well as 100 healthy individuals as control. The relevant clinical history of each patient was extracted from their case notes. All the subjects had their testes examined using a high frequency (7.5 mHz) linear transducer of an ultrasound scanner. The results were expressed as percentages and tests of significance were done using the chi-square and Student’s t-test. A P-value < 0.05 was considered statistically significant.
Results: The mean testicular volume for the sub-fertile patients was 15.32 ml while it was 19.89 ml in the control group. There was a statistically significant difference between the testicular volumes in fertile and infertile men at different age groups, while there was an inverse relationship between testicular volume and severity of oligospermia. This was, however, not directly linear as a mean testicular volume of 18–20 ml was associated with highest semen density. Volumes higher than 20 ml and lower than 18 ml were associated with reduced sperm density. There was also a sharp decline in sperm density when the mean testicular volume reduced from 14 ml to 13 ml. Severe oligospermia (<5 million/ml) was associated with mean testicular volume less than 12 ml.
Conclusion: Testicular volume on scrotal ultrasound correlates well with severity of oligospermia in men with sub-fertility. While the critical mean testicular volume necessary for adequate spermatogenesis has not been determined, it appears there is an optimal testicular volume of 18–20 ml at which spermatogenesis is at its peak in sub-fertile Nigerian men.

KEYWORDS: Optimal testicular volume; Male infertility; Ultrasound; West Africans