Symptoms of a blood clot in the calf, also known as deep vein thrombosis, include swelling, pain and tenderness, especially with standing or movement, and warmth or redness in the affected leg, according to WebMD. The leg may also be discolored, have visible surface veins and fatigue easily.
A blood clot can break free from its original site, travel to the lungs and block the small vessels, causing a pulmonary embolism, explains the National Blood Clot Alliance. Sudden shortness of breath, stabbing chest pain, rapid heart rate and an unexplained cough with bloody mucus are symptoms of this life-threatening condition.
Risk factors for deep vein thrombosis include extended bed rest due to illness, injury or surgery, sitting for long periods of time, having previous deep vein thrombosis or pulmonary emboli and having cancer, heart failure or inflammatory bowel disease, according to Mayo Clinic. Other risk factors include inherited blood clotting disorders, pregnancy, the use of birth control pills, smoking, obesity and older age.
While a pulmonary embolism is the most significant complication of deep vein thrombosis, it isn't the only one, notes Mayo Clinic. Postphlebitic syndrome occurs after a blood clot due to damage to the vein from the clot itself. It may not occur for several years after the clot resolves, or it may appear right away. Symptoms include swelling, skin discoloration, pain and skin sores.