Lower limb vascular ultrasound can check arteries and deep veins of lower limbs, as follows: 1. Arterial vascular ultrasound: It is to assess whether there is atherosclerosis, plaque, aneurysm, stenosis, ischemia, etc. in large arteries. If patients with atherosclerosis, especially diabetic patients, if the ultrasonographer can detect atherosclerosis in time, they can be treated with timely stenting, which can eliminate the risk of amputation; 2. Deep vein ultrasound: it is mainly to check whether there is thrombosis, whether there are varicosities, and whether they are high-risk factors for pulmonary embolism. If a patient with long-term bed-ridden surgery finds swelling and leg pain in lower limbs, it is often venous thrombosis, and ultrasound can observe whether there is venous thrombosis in lower limbs and the location of thrombosis at this time.