A varicocele is an abnormal enlargement of the spermatic vein within the scrotum. This can result from poor valve function, causing a build up of blood as it struggles to travel through the failing scrotal veins. Varicoceles present in a similar way to a more commonly known condition called varicose veins, which occur in the legs.

Currently, doctors are unsure of the exact risk factors that contribute to the development of  varicoceles. Men of any age can experience varicoceles, and they have been shown to occur as early as puberty. Men who are overweight or obese could be at a higher risk of suffering from varicoceles, but there have not been enough studies to say this conclusively. There is a higher likelihood of varicocele forming on the left scrotum but can occasionally occur on both sides.