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.
Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine; Scott Miller, MD, Urologist in private practice in Atlanta, Georgia. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.