A varicocele is abnormal dilation and enlargement of the scrotal venous pampiniform plexus which drains blood from each testicle. While usually painless, varicoceles are clinically significant because they are the most commonly identified cause of abnormal semen analysis, low sperm count, decreased sperm motility, and abnormal sperm morphology.The testicular veins originate in the testicle and form the pampiniform plexus. Venous blood then travels up through the inguinal canal as part of the spermatic cord, forms the internal spermatic or testicular vein and terminates in the abdomen. The right internal spermatic vein terminates directly into the low-pressure inferior vena cava while on the left side, it joins with the relatively high-pressure left renal vein. This anatomy explains why the majority of clinically detectable varicoceles are on the left side.