Firstly, the most common cause is prolonged postoperative fasting leading to malnutrition, hypoproteinemia and edema, which can be manifested as ascites and lower limb edema. Total parenteral nutrition is needed to improve the patient’s nutritional status, and supplemental human albumin or diuretic therapy can alleviate to disappear. Second, long-term bed rest causes lower extremity lymphatic flow disorders manifested as lower extremity edema, and patients are advised to get out of bed early to promote lymphatic flow can improve the symptoms. Thirdly, we need to be highly alert to the lower limb deep vein thrombosis caused by poor blood viscosity and long-term bed rest in elderly patients, and we need to perform vascular ultrasound examination of lower limb to make a clear diagnosis. In case of lower limb deep vein thrombosis, a filter or even thrombolytic therapy is needed.