Incompetent or inadequate valves within the veins along the spermatic cord cause a varicocele. The abnormal valves interfere with normal blood flow, causing a backup of blood and resulting in enlarged veins. Varicoceles usually develop slowly, with no symptoms. Varicoceles are a possible cause of reduced fertility in men.
Review Date: 1/25/2013
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Senior Physician, Massachusetts General Hospital.