Varicocele (VAR-ih-koe-seel) describes a condition with swollen and enlarged veins in the scrotum (Figure 1). These veins carry blood from the testicles that is low in oxygen and nutrients. Swelling can happen when blood flows backward in the veins. Varicoceles are similar to varicose veins in the leg.
Varicoceles are common in prepubescent and adolescent boys. They are uncommon in boys younger than age 10 and rarely develop after adolescence. Most varicoceles are found only on the left side because of the way blood drains from the left testicle. In some cases they can also develop above the right or in both testicles.
Varicoceles usually are not painful and do not need treatment. However, treatment might be advised if a varicocele:
Varicoceles can affect fertility by reducing blood flow and raising the temperature of the testicles. This can cause the testicles to produce fewer sperm, and sperm that is produced might not be healthy. Early treatment can help produce healthier sperm and even regrowth of a testicle.