A varicocele occurs when there is a dilatation of the testicular veins within the spermatic cord. Varicoceles are not uncommon, with an incidence of about 15% of all healthy fertile men. Therefore, it is not generally considered necessary (or useful) to surgically repair all varicoceles, especially if the manís semen analysis is normal.
When a varicocele does affect sperm quality, it is thought to do so primarily by exposing the sperm (that is residing in the epididymis or sperm being produced in the testes) to excessive heat.
The testes and the epididymis are normally a few degrees cooler than ďcore body temperatureĒ since they are contained within the scrotal sac (which hangs down from the remainder of the body). However, blood within the bodyís vascular system circulates throughout the body quite often (a normal heart rate is 80 beats per minute) and therefore is maintained at core body temperature. When a varicocele brings a large amount of circulating blood (at core body temperature) very close to stored sperm (in the epididymis) or maturing sperm (in the testes) this can reduce the spermís ability to function properly.