The National Institutes of Health (NIH) defines a varicocele as a widening of the veins along the cord that holds up a man's testicles.
According to KidsHealth.org, the spermatic cord, the structure containing arteries, veins, nerves, and tubes, provides a connection and circulates blood to and from the testicles. Veins carry blood flowing from the body back toward the heart, and valves in the veins keep the blood flowing one way and stop it from flowing backward.
Sometimes these valves fail and some blood flows in reverse. This backed-up blood can collect in pools in the veins, which then causes them to stretch, enlarge or become swollen creating a varicocele.
Medical News Today reports approximately 15 percent of men have a varicocele. NIH says they’re more common in men ages 15 - 25. KidsHealth.org says they mostly occur during puberty because at that time, testicles grow rapidly and need more blood delivered to them.
It’s common to experience no signs or symptoms. NIH lists symptoms as enlarged, twisted veins in the scrotum (often described as feeling "like worms”), a painless testicle lump, scrotal swelling, or a bulge within the scrotum.
Medical News Today says in some cases there may be dull or sharp pain, or a sensation of heaviness. The pain may also get worse later in the day or decrease when lying down.
KidsHealth.org says symptoms tend to occur during hot weather, after heavy exercise, or when a male has been standing or sitting for an extended time.
The Mayo Clinic says varicoceles may cause atrophy of the affected testicle and can be a cause of low sperm production and decreased sperm quality. It's not clear how varicoceles affect fertility.
The testicular veins cool blood in the testicular artery, helping maintain the proper temperature for optimal sperm production. By blocking blood flow, a varicocele may keep the local temperature too high, affecting sperm formation and movement.
NIH says initial treatment may be a scrotal support or snug underwear. However, if there is pain, testicle shrinkage, or sperm count and quality is affected, Medical News Today says surgery may be performed.