The blood vessels of the thigh are divided into arterial vessels and venous vessels, and the symptoms that appear when the blood vessels of the thigh are blocked are different according to the corresponding vessels. If the obstruction is in the arterial vessels of the thigh, the symptoms will be ischemic, such as ischemia in the distal thigh, calf and foot, which can be manifested as local pallor, hypothermia, pain, numbness and abnormal sensation, and these symptoms will be aggravated after walking, and in severe cases, the toes will be bruised or even gangrenous. If the obstructed blood vessel is a vein in the thigh, the main symptom is swelling due to restricted reflux, which is caused by the thrombus blocking the venous return pathway, resulting in corresponding swelling, weakness, reddening of skin color, and increased skin temperature. When a blood vessel obstruction is suspected in the thigh, an ultrasound examination is recommended to determine whether the obstructed vessel is an artery or a vein, and to choose the appropriate treatment method under the guidance of a vascular surgeon.