In a male with infertility and a left testicle smaller than the right, what is the most common diagnosis?

In this scenario, the most common diagnosis for a male experiencing infertility, along with a notable asymmetry in testicle size (specifically, a smaller left testicle compared to the right), is varicocele. A varicocele is characterized by the enlargement of veins within the scrotum, and it is often associated with fertility issues.

The relationship between varicocele and infertility is well established, as the condition can lead to impaired sperm production and function. The engorgement of the veins can elevate the temperature in the testicular area, negatively impacting spermatogenesis (the production of sperm). Additionally, the affected testicle may exhibit reduced size, which is commonly seen in men with varicoceles.

Diagnosing varicocele typically involves a physical examination, where a size discrepancy between the testicles, particularly in the context of infertility, raises suspicion for this condition. Treating varicocele can potentially improve fertility outcomes for affected individuals.

While other options may present with symptoms related to reproductive health, they do not align as closely with the combination of infertility and asymmetrical testicle size as varicocele does in this context.