Pathophysiology of varicocele in male infertility in the era of assisted reproductive technology.

Varicocele is the most common and treatable cause of male infertility. Studies of a rat experimental left varicocele model and human testicular biopsy samples have shown the involvement of various factors in its pathophysiology. Among them, oxidative stress plays a major role in impairing spermatogenesis and sperm function. Therefore, in addition to palpation, scrotal ultrasonography and color Doppler ultrasound, evaluation of testicular oxidative stress (e.g. scrotal temperature is a surrogate parameter) is recommended to enable diagnosis and suitable treatment of varicocele. Varicocelectomy increases the fertilization, pregnancy and live birth rates, indicating improved sperm function; it is therefore important even in couples undergoing intracytoplasmic sperm injection. Routine sperm-function tests are warranted to monitor the sperm quality after varicocelectomy and consequent improvement in the outcomes of assisted reproductive technology. Furthermore, the indications of varicocelectomy in assisted reproductive technology should be widened.