A varicocele is a varicose vein tumor formed by an (unusually swollen vein) or a group of varices, usually located in the scrotum or in the spermatic cord. Usually develops during the course of puberty, most often on the left side of the scrotum, and although it is usually not harmful, in some people it can damage the testicles or decrease sperm production. If testicular varicocele causes infertility, surgery, called varicocelectomy, which involves cutting the affected veins for blood flow is performed. An alternative to surgery is varicocele embolization, which makes a much smaller incision and involves placing a catheter into the vein.