Varicocele is an abnormal enlargement of the veins in the scrotum draining the testicles. The testicular blood vessels originate in the abdomen and course down through the inguinal canal as part of the spermatic cord on their way to the testis. Up-ward flow of blood in the veins is ensured by small one-way valves that prevent backflow. Defective valves, or compression of the vein by a nearby structure, can cause dilatation of the veins near the testis, leading to the formation of a varicocele.