The varicocele: a critical analysis of experimental and clinical data.

A number of reports have shown that serotonin has a detrimental effect on spermatogenesis and androgen synthesis. Serotonin has 2 mechanisms of action on the testicle: 1) vasoconstrictive changes and 2) direct alterations of testicular metabolism and endocrine activity. The data in animals with the experimental varicocele clearly mimic the human situation. All of the seminal parameters except volume are decreased after creating the varicocele. In many infertile patients with a varicocele serotonin may be the inciting factor that results in subfertile semen parameters. This is corroborated by the presence of elevated serotonin levels in spermatic vein plasma of certain patients with a varicocele. More data comparing the relationship between spermatic vein and peripheral blood serotonin levels in patients with and without a varicocele are needed. This investigation also is being pursued in patients undergoing inguinal operations for lesions other than a varicocele.