Symptoms of superior vena cava obstruction syndrome mainly include hematochezia and edema, dyspnea, dizziness, vomiting, and related physical symptoms. 1. Blood stasis and edema: As superior vena cava is located in the middle mediastinum of the body, poor blood circulation in the veins of the upper limbs leads to congestion and swelling of the patient’s head, neck and upper limbs. The bruises and edema on the patient’s body will be more clear and obvious when he/she lowers his/her head, bends over or lies down. 2. Difficulty in breathing, dizziness, vomiting: If the degree of superior vena cava obstruction gradually aggravates, the trachea, right bronchus, hilar and esophagus distributed around the superior vena cava can be compressed, forming the superior vena cava collateral circulation, which leads to headache, dizziness, distension of the head, drowsiness, shortness of breath, blurred vision and other clinical symptoms. In addition, when the patient sleeps, it may be accompanied by loud snoring, and in severe cases, the neck may even become thicker, which will eventually affect the shape of the face gradually. 3. Related signs and symptoms: Through examination, the patient has sublingual varicose veins, swollen neck veins, congestion of the upper limbs, malignant abdominal varicose veins of the lower limbs, and at the same time, the pressure of the superior vena cava is extremely high. Through X-ray fluoroscopy, the patient can be found to have localized shadows in the superior mediastinum and superior vena cava, or through superior vena cava angiography, the initial location of superior vena cava obstruction can be determined, and ultimately, the development of superior vena cava obstruction syndrome can be determined. Patients with superior vena cava obstruction syndrome should go to the hospital promptly for examination and treatment under the supervision of a doctor.