Often compared to unsightly varicose veins that develop in the legs, varicoceles are stretched and enlarged veins that become twisted in the scrotum. They usually develop slowly and are more common on the left side of the scrotum. Symptoms can include aching pain, a painless lump in the testicles, scrotal swelling or a bulge in the scrotum. There may also be a twisted growth along the spermatic cord, or the testicle on the side of the varicocele may be smaller than the other testicle.

Varicoceles develop when blood flow to and from the testicles is disrupted. Blood normally flows into the testicles through an artery and leaves through a network of very small veins that feed into a long vein that runs through the abdomen. A series of one-way valves ensures the blood flows on to the heart. Sometimes these valves fail and blood flows back into the testicles, stretching, enlarging and tangling the small veins into varicoceles.

Symptoms may be mild and not require treatment. For severe cases where varicoceles are painful or associated with male infertility, surgical removal—either open or laparoscopic—may be required, or minmally invasive percutaneous embolization may be performed to divert blood flow away from the varicoceles.