Swelling and pain in the right calf with extensive bruising may be caused by external collision, deep vein thrombosis of the lower extremity, blood system diseases and other factors. 1. External collision: when the calf area is hit by the outside world, it may cause local soft tissue injury or fracture, leading to subcutaneous bleeding, which will result in swelling and bruising. 2. Deep vein thrombosis of the lower limbs: when thrombosis occurs in the deep vein vessels of the lower limbs, it will affect the venous return and circulation of the lower limbs, resulting in swelling and pain in the calves and bruises under the skin. 3. Blood system diseases: Blood system diseases will lead to blood coagulation dysfunction and blood circulation abnormality, which will easily cause swelling and pain in the calf, large bruises and other uncomfortable symptoms. There are other diseases that cause swelling and pain in the right calf, large bruises, such as persistent unrelieved, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, and follow the doctor’s instructions for targeted treatment to avoid delays in the condition.