Venous circulation is comprised of superficial veins and deep veins. If a blood clot blocks a vein, you may experience:

• Tenderness or swelling of the affected extremity
• Pain and/or a cramping feeling
• Fever
• Discoloration of the skin, in severe cases

If a deep vein becomes blocked with a blood clot, a serious medical condition called deep vein thrombosis can occur and result in severe circulation problems in the extremity involved. Left untreated, the blood clot can break away and travel to the lungs, a condition called pulmonary embolus. Severe breathing problems or even death can occur if a pulmonary embolus is not promptly treated.

Causes of venous blood clots can include:

• Recent surgery
• A major illness resulting in prolonged bed rest
• Traumatic injury
• Sitting for long periods of time, such as on long trips in a car or airplane
• Certain medications and diseases which make you more susceptible to blood clots