Varicose and Spider Veins Varicose veins and spider veins can cause varying degrees of discomfort. Symptoms may be mild, but if left untreated, advanced problems can develop. Deep Vein Thrombosis (DVT) DVT is a blood clot, or thrombus, within a vein of the leg. A DVT is dangerous because clots in the legs can potentially travel through the veins to the lungs. Pulmonary Embolism (PE) When a clot reaches the lungs, it is known as a pulmonary embolism (PE). Chronic Venous Disease Patients with a history of blood clots in their legs (DVT) or a long history of varicose veins can develop chronic venous disease. Pelvic Congestion Syndrome In women, pelvic congestion syndrome is caused by poorly functioning veins in the ovaries and pelvic region. Varicocele In men, varicocele is caused by poorly functioning veins in the scrotum and pelvic region.