Incompetent or inadequate valves within the veins along the spermatic cord cause a varicocele. The abnormal valves obstruct normal blood flow causing a backup of blood, resulting in enlargement of the veins. Varicoceles usually develop slowly and usually have no symptoms. Varicoceles are a common cause of infertility in men.
Update Date 10/2/2013
Updated by: Scott Miller, MD, Urologist in private practice in Atlanta, Georgia. Also reviewed by David Zieve, MD, MHA, Bethanne Black, and the A.D.A.M. Editorial team.