The relationship of testicular stiffness with Johnsen score and sperm retrieval outcome in men with non-obstructive azoospermia.

BACKGROUND: The pathological Johnsen score (JS) is a quantitative histological scoring system used to assess spermatogenesis in men with nonobstructive azoospermia (NOA), while elastic modulus derived from shear wave elastography (SWE) is a diagnostic tool for evaluating spermatogenic dysfunction. In this prospective observational study, we aimed to investigate whether testicular stiffness measured by SWE could serve as a substitute for JS in predicting sperm retrieval outcomes in men with NOA.

METHODS: This prospective cohort study analyzed 140 testes from 115 consecutive outpatient participants with NOA who had sought treatment at the reproductive medical center of a tertiary care hospital between January 2018 and October 2021. Testicular volume, elastic modulus, JS, and sperm retrieval outcomes were calculated. Statistical differences in parameters between the positive and negative sperm retrieval groups were determined using the Mann-Whitney test. Spearman rank correlation analysis was performed to determine the correlations between JS and either testicular volumes or elastic modulus. Receiver operating characteristic (ROC) curves were drawn to evaluate the diagnostic performance of the testicular elastic modulus and testicular volume.

RESULTS: The JS correlated positively with testicular volume and negatively with the maximum elastic modulus (Emax) and mean elastic modulus (Emean), with correlation coefficients of 0.804, -0.686, and -0.456, respectively (P<0.01). There were significant differences in JS, testicular volume, and Emax between participants with positive and negative sperm retrieval of microdissection testicular sperm extraction (micro-TESE) (P<0.01). ROC curves were plotted for JS, testicular volume, and Emax to distinguish between participants with positive and negative sperm retrieval. The areas under the ROC curves (AUCs) were 0.783 [95% confidence interval (CI): 0.707-0.859; P<0.01], 0.737 (95% CI: 0.651-0.823; P<0.01), and 0.729 (95% CI: 0.643-0.814; P<0.01), respectively. When the cutoff value of JS was 4.5, its sensitivity and specificity were 60.3% and 89.6%, respectively. When the cutoff value of Emax was 3.75 kPa, its sensitivity and specificity were 79.1% and 64.4%, respectively. The sensitivity and specificity were 68.5% and 83.6%, respectively when the cutoff value of testicular volume was 8.17 mL. Emax combined with testicular volume improved this diagnostic value, with an AUC of 0.742 (95% CI: 0.657-0.828; P<0.01), and sensitivity and specificity were 83.6% and 68.5%, respectively.

CONCLUSIONS: Our study suggests that the combination of testicular stiffness and volume measurements may serve as a viable alternative to pathological JS in predicting the likelihood of successful sperm retrieval prior to micro-TESE procedures.