Swollen thigh roots are most often caused by infection and inflammation, especially in the lower extremities, which can easily lead to enlargement of lymph nodes in the inguinal region, and the patient will also have significant pain and fever, which can be gradually reduced after effective anti-infection treatment. Some patients have deep vein thrombosis of the lower extremities, which may manifest as swelling of the limbs, especially iliac vein thrombosis combined with femoral vein thrombosis, and patients may also have fever and severe edema and tense blisters in the distal extremities. Thrombosis includes slow blood flow in the lower extremity, damage to the intima, and hypercoagulability of the blood. After the diagnosis is clear, anticoagulation therapy should be chosen promptly, because the thrombus embolus is dislodged and also prone to the occurrence of pulmonary artery embolism.