The presence of swelling and pain in the lower body is most commonly the result of venous system disease. In some patients, it is due to abdominal space-occupying lesions compressing the iliac veins, secondary to deep vein thrombosis of the lower extremities, and also combined with iliac vein thrombosis. Patients will have obvious edema of the lower limbs, irregular low-grade fever, and tense blisters of the limbs, which will also manifest as edema of the lower abdominal wall, and even localized secondary infections. Anticoagulant therapy should be actively carried out, and interventional therapy should also be carried out to intercept the thrombus and prevent the occurrence of fatal pulmonary embolism. Deep vein thrombosis of the lower extremities is commonly associated with bed rest, external pressure on the blood vessels, and endothelial damage, and should be treated early when the diagnosis is clear, and should be reviewed regularly. Some patients have thrombophlebitis due to varicose veins in the lower limbs, which may cause swelling and pain in the lower limbs.