Dr. Adam Geronemus, Vascular and Interventional Radiologist at Miami Cardiac and Vascular Institute, explains varicocele is dilatation or dilated veins within the scrotum. “When the valves don’t function, if the blood flows the wrong way, the veins become dilated. It is a tangle in the scrotum,” he says. Dr. James Benenati, Director of Non-Invasive Vascular Laboratory at Miami Cardiac and Vascular Institute, points out the veins generally work passively by allowing gravity to push the blood back towards the heart, but when those valves malfunction, the blood flows up and it flows back down.