Stretched penile length and infertility, a new association

Abstract

Male infertility can be associated with secondary sexual characteristics and several findings in the examination of external genitalia. We sought to identify if stretched penile length (SPL) is associated with infertility. Retrospective review of all males age 18-59 presenting to a Men’s health clinic from 2014 to 2017. SPL of patients with infertility were compared to patients with any other complaint such as erectile dysfunction or testicular pain. Patients with Peyronie’s disease, prior penile surgery, or prostatectomy were excluded from our study. Basic characteristics including age, body mass index (BMI), and race were collected. SPL was measured from pubic symphysis to meatus, with penis on maximal stretch by a total of 3 trained providers. T-test and Chi-square test were used to compare baseline characteristics between the two groups (infertile vs. other). Linear regression was used to assess the association between infertility with SPL after adjusting for patient age, BMI, and race. 815 men were included in our study (219 infertile, 596 other). Infertile men were younger than the other group (33.6 vs. 42.5 years, P<0.001). BMI did not significantly differ (29.2 vs 29.5 kg/m2, p=0.57). In both infertile and other group about 85% were white/Caucasian (85.6 vs. 84.3 respectively) but overall the difference in race was statistically significant (p=0.02). The unadjusted mean of SPL in the infertile group was 12.3 cm compared to 13.4 cm in the other group (p<0.001). When adjusted for age, BMI, and race, SPL in infertile group was 12.5 cm compared to 13.4 cm in other (p<0.001, 95% CI: 12.2-12.8 vs. 13.2-13.5 respectively). This is the first study to demonstrate an association between a shorter SPL and infertility. It is unknown if reduced length is a result of genetic or congenital factors associated with infertility such as testicular dysgenesis syndrome or the result of underlying hormonal differences between the two groups. Further investigation is needed to better understand the association of shorter stretched penile length with male infertility.