Purpose: Overall, male factor infertility (MFI) accounts for up to 50% of etiologies of couple’s infertility, with almost 30% of MFI cases being idiopathic in nature. Idiopathic MFI does not support a tailored treatment work-up in clinical practice. To investigate rates of and characteristics of men presenting for idiopathic versus unexplained primary infertility as compared with same-ethnicity, age-comparable fertile men. Materials and Methods: Demographic, clinical and laboratory data from 3,098 primary infertile men consecutively evaluated were analyzed and compared with those of 103 fertile controls. Idiopathic male infertility (IMI) was defined for abnormality at semen analysis with no previous history of diseases affecting fertility and normal findings on physical examination and genetic and laboratory testing. Unexplained male infertility (UMI) was defined as infertility of unknown origin with completely normal findings at semen analysis. Descriptive statistics and logistic regression models tested the association between clinical variables and idiopathic infertility status. Results: Overall, 570 (18.5%) and 154 (5.0%) patients depicted criteria suggestive for either IMI or UMI, respectively. Groups were similar in terms of age, BMI, CCI, recreational habits, hormonal milieu, and sperm DNA fragmentation indexes. Conversely, testicular volume was lower in IMI (p<0.001). Vitamin D3 levels were lower in IMI vs. UMI vs. fertile controls (p=0.01). At multivariable logistic regression analysis only vitamin D3 deficiency (OR, 9.67; p=0.03) was associated with IMI. Characteristics suggestive for IMI versus UMI were observed in almost 20% and 5% of men, respectively. Overall, clinical differences between groups were slightly significant and certainly not supportive of a tailored management work-up. Conclusions Current findings further support the urgent need of a more detailed and comprehensive assessment of infertile men to better tailoring their management work-up in the everyday clinical setting.

Substances of abuse (SoA), as well as smoking and alcohol consumption, are well known for their impact on male fertility status, erectile function, and ejaculation. We assessed SoA consumption habits in a cohort of men seeking medical attention for uro-andrological purposes. Data from 7447 men seeking medical attention for the first time for uro-andrological purposes were analyzed. A complete medical and sexual history was collected for each patient. Smoking, alcohol, and SoA consumption were investigated. Descriptive statistics was used to describe the whole cohort. The primary motivations for their evaluation were lower urinary tract symptoms (LUTS), erectile dysfunction (ED), and infertility in 1912 (25.7%), 2944 (39.5%), and 2591 (34.8%) men, respectively. Previous use of SoA was reported by 378 (5.1%) men, and 190 (2.6%) individuals were current users. Patients seeking medical attention for infertility were more frequently current SoA users (107; 4.1%) than men with ED (66; 2.2%) and LUTS (17; 0.9%) (both P < 0.001). Current users of SoA were younger than those with past or no SoA history (P < 0.001). Current SoA users were more frequently smokers (P < 0.001) and alcohol consumers (P < 0.001) than those with a previous history or those who had never tried SoA. In conclusion, approximately 3% of men seeking medical attention for uro-andrological purposes were current SoA consumers. Infertile men reported a higher use of SoA than those with ED or LUTS. Current SoA users were younger and more frequently concomitant smokers and alcohol consumers compared to those who did or had never used SoA.

Testicular volume (TV) is considered a good clinical marker of hormonal and spermatogenic function. Accurate reference values for TV measures in infertile and fertile men are lacking. We aimed to assess references values for TV in white-European infertile men and fertile controls. We analyzed clinical and laboratory data from 1940 (95.0%) infertile men and 102 (5.0%) fertile controls. Groups were matched by age using propensity score weighting. TV was assessed using a Prader orchidometer (PO). Circulating hormones and semen parameters were investigated in every male. Descriptive statistics, Spearman's correlation, and logistic regression models tested potential associations between PO-estimated TV values and clinical variables. Receiver operating characteristic (ROC) curves were used to find TV value cutoffs for oligoasthenoteratozoospermia (OAT) and nonobstructive azoospermia (NOA) status in infertile men. The median testicular volume was smaller in infertile than that of fertile men (15.0 ml vs 22.5 ml; P < 0.001). TV positively correlated with total testosterone, sperm concentration, and progressive sperm motility (all P ≤ 0.001) in infertile men. At multivariable logistic regression analysis, infertile status (P < 0.001) and the presence of left varicocele (P < 0.001) were associated with TV < 15 ml. Testicular volume thresholds of 15 ml and 12 ml had a good predictive ability for detecting OAT and NOA status, respectively. In conclusion, infertile men have smaller testicular volume than fertile controls. TV positively correlated with total testosterone, sperm concentration, and progressive motility in infertile men, which was not the case in the age-matched fertile counterparts.