Clinical and seminal parameters associated with testicular microlithiasis and its severity in males from infertile couples

Study question: Is there an association of testicular microlithiasis (TM) and its severity with testicular dysfunction in men from infertile couples? Summary answer: The presence of ≥5 testis microcalcifications per sonogram at the scrotal ultrasonography (US) of infertile males was associated with a more severe testicular dysfunction as compared to males with limited, or without, TM. What is known already: TM, representing an incidental finding in the scrotal US, is associated with male infertility and a higher risk for testicular cancer as compared to that in infertile males without TM. Still, there are unresolved questions on the relation between TM severity and testicular dysfunction in infertile men, as well as on the identification of risk factors for TM. Study design, size, duration: This study was an observational, retrospective, case-control investigation involving males who underwent clinical evaluation, measurement of reproductive hormones, seminal analysis and scrotal US as part of diagnostic work-up for couple infertility at an andrology clinic, between January 2004 and December 2018. One hundred patients, out of the 2112 scored men, were found to have TM during the US evaluation. One hundred male partners from 100 infertile couples without TM, comprising the control group, were selected through a matched analysis by age and date of evaluation to reduce the confounding effect of both age and technique variability all along the long period of observation. Participants/materials, setting, methods: TM was defined as limited TM (LTM) or classical TM (CTM), when the maximum number of hyperecogenic spots per sonogram was <5 or ≥5, respectively. CTM, LTM and control groups were compared for clinical variables, serum levels of FSH, LH, and total testosterone, as well for semen parameters and scrotal US features. Main results and the role of chance: After the exclusion of cases with testicular nodules to eliminate the possible confounding effect of testis cancer on testicular dysfunction, cases with CTM showed a lower mean testis volume (P = 0.03) and a lower sperm concentration (P = 0.03) as compared to the other two groups. A higher FSH level was observed in the CTM group compared to the LTM group (P = 0.02) and in controls (P = 0.009). The multiple logistic regression analysis showed that only a smaller testicle volume exhibited an independent significant association with a higher odds of detecting CTM (odds ratio = 0.84, 95% CI: 0.75-0.94; P = 0.02). No significant differences were observed between groups in the prevalence of risk factors for testicular cancer, or in the prevalence of conditions associated with TM. Limitations, reasons for caution: The retrospective design of the study did not allow conclusions to be drawn about the possible underlying links in the associations of TM with defective spermatogenesis. Wider implications of the findings: Males from infertile couples who exhibit a reduced testicular volume should undergo scrotal US, independent of sperm parameters, to exclude CTM and, eventually, testis cancer, although the association of CTM and current or future testis cancer risk is not yet clear. Evidence is provided here demonstrating that the presence of LTM has no clinical relevance in males from infertile couples.