Testicular ultrasound (TU) score: a new proposal for a scoring system to predict testicular function

Background Testicular ultrasound (US) is routinely employed in the evaluation of reproductive and sexual function. However, its use for characteristics other than testicular volume is hampered by a lack of information on the prognostic value of its findings, which to date have only been incorporated in a score proposed by Lenz et al. in 1993. Objectives We sought to explore whether testicular US examination can predict the quality of spermatogenesis and provide information on testicular endocrine function. Materials and methods We retrospectively reviewed 6210 testicular US examinations, finally selecting examinations from 2230 unique men. The following variables were considered: bitesticular volume and testicular asymmetry, parenchymal echotexture, echogenicity and presence of microlithiasis, solid lesions and varicocele. Concurrent fasting hormonal data were available for 1160 men, while 979 had a semen sample available from the same day as the US exam. Results We derived a new US score, termed TU score, that can predict both impaired spermatogenesis (AUC 0.73, sensitivity 72%, specificity 61%, p <0.001) and hypogonadism (AUC 0.71, sensitivity 71%, specificity 53%, p <0.001) more accurately than the Lenz's score. In a multivariate analysis, a reduced sperm composite index (defined as total spermatozoa x total motility x normal forms) was independently predicted by bitesticular volume and by inhomogeneous echotexture, while hypogonadism was independently predicted also by reduced echogenicity and presence of microlithiasis. Discussion and conclusions We describe the testicular US characteristics that are independently associated with impaired spermatogenesis and hypogonadism and propose the TU score as a simple screening method for use in subjects referred for testicular US.