Testis temperature, infertility, and the varicocele paradox.

The author presents arguments which favor elevated temperature of the testis and adnexae as an important factor in patients with poor semen seen in varicocele and "idiopathic" infertility. This appears to be primarily the result of disturbed thermoregulation due to internal spermatic vein retrograde blood flow. Elevated testis temperature without varicocele may be present in as high as 54% of all patients with "idiopathic" infertility. The prevailing theory in the United States is that the varicocele's bilateral effect is due to a substance noxious to spermatogeneis which is carried to both testes by retrograde internal spermatic vein blood flow and via crossover to the contralateral testis. A review of the published evidence for the crossover does not confirm its presence in the deep circulation of the contralateral testis, but rather its restriction to the superficial contralateral scrotal venous drainage. A simpler explanation for the bilateral effect of varicocele on spermatogenesis and sperm maturation by the epididymis is a gradient to the contralateral testis from the affected testis which results in demonstrable elevated temperature in both.