Symptoms of deep vein thrombosis include pain in the leg muscles that worsens when pressure is applied, swelling of the legs, redness or warmth near the affected site, and skin that appears bluish in colour. Deep vein thrombosis is the condition of a Blood clot inside one or more veins deep below the skin surface, such as in the leg. Deep vein thrombosis (DVT) can also occur in some other parts of the body, e.g., the arm and pelvis. Deep vein thrombosis is a Blood clot that forms inside a vein deep in the body.