I. What is TV mediastinoscopy? Mediastinoscopic surgery is a means of examination for upper mediastinal diseases. Although it has a history of more than 40 years, it is still one of the most important means for diagnosis and treatment of mediastinal diseases as well as preoperative pathological staging of lung cancer because of its irreplaceable advantages such as minimally invasive, safe, and reliable material extraction. Cervical mediastinoscopy: Under general anesthesia, single-lumen threaded tracheal intubation and fixation on the side of the orofacial angle, supine position with the head excessively tilted back, and disinfection and towel laying according to the median sternotomy. A 3-cm transverse incision was made at a transverse finger above the sternotomy, and the broad neck muscle and the cervical white line were incised, and the trachea was revealed by longitudinal separation and distraction of the pre-tracheal muscles on both sides, and the pre-tracheal fascia was incised, and the pre-tracheal space was bluntly separated downward along the midline with the index finger against the trachea to form an artificial tunnel to reach the tracheal bifurcation, and a mediastinoscope was placed along the artificial tunnel. The suspicious masses or enlarged lymph nodes on both sides of the trachea and under the bulge, left and right main bronchus were observed separately. After the lesion or biopsy site is clearly identified, a fine needle puncture is performed to exclude the blood vessels before biopsy. II. What are the advantages of TV mediastinoscopy? Because of its irreplaceable advantages such as minimally invasive, safe and reliable sampling, it is still one of the most important means for diagnosis and treatment of mediastinal diseases and preoperative pathological staging of lung cancer. Which chest diseases can be diagnosed and treated by TV mediastinoscopy? (1) Diagnosis of difficult chest diseases Due to the special anatomical position of mediastinum, there is no natural cavity to connect with the outside world, and at the same time, due to the diversity of mediastinal tissue sources, there are many causes of mediastinal enlarged lymph nodes or masses, and it is difficult to obtain a clear pathological diagnosis by general examination methods, resulting in mediastinal masses, especially mediastinal peri-tracheal lesions, which often become a difficult point in diagnosis and easily lead to misdiagnosis and mistreatment. This makes this type of disease a difficult clinical task. Although chest CT and magnetic resonance imaging (MRI) can clarify the location of mediastinal lesions, the size and shape of the mass, and the relationship with the surrounding organs, the nature of the lesions cannot be determined. In recent years, with the continuous application of PET-CT in clinical practice, although the accuracy of imaging to distinguish benign and malignant tumors has been significantly improved, there are still certain false-positive and false-negative rates, especially for the differential diagnosis of low-grade malignant tumors and chronic granulomatous inflammatory diseases such as mediastinal lymph node tuberculosis and nodular disease, which is difficult to be satisfied. And only the benignity and malignancy can be judged, but not the pathological diagnosis can be clarified. Although transthoracic aspiration cytology examination under the guidance of B ultrasound or CT has the advantages of easy operation, small trauma and good patient tolerance, the accuracy of this method is often unsatisfactory due to the small amount of tissues obtained and the disadvantages of cytology examination itself, and the confirmation rate is reported to be 78%. (2) Preoperative lymph node staging of lung cancer The preoperative PTNM staging of lung cancer patients is of great significance in determining the treatment plan and prognosis. Among them, for patients with non-small cell lung cancer who may be operated, preoperative clarification of mediastinal lymph node (N2) metastasis is even more crucial. At present, it is considered that patients without lymph node metastasis stage I (N0) or only intrapulmonary or hilar stage II (N1) lymph node metastasis can generally be treated by direct surgical resection, while those with ipsilateral (N2) or contralateral (N3) mediastinal lymph node metastasis should not be treated by surgery first. For patients with stage III (N2, N3) lung cancer, the effect of pure surgical treatment is often poor. Several overseas randomized comparative studies on preoperative neoadjuvant chemotherapy plus surgery versus surgery alone for non-small cell lung cancer suggest that preoperative neoadjuvant chemotherapy can increase the 5-year survival rate by about 2 times after surgery. This shows that it is important to clarify preoperatively whether the mediastinal lymph nodes are metastatic, especially in N2, for lung cancer patients. TV mediastinoscopy not only enables these patients to obtain a clear pathological stage before surgery, but also provides the best basis for the formulation of surgical treatment plan for lung cancer. IV. What are the complications of TV mediastinoscopy? Complications of mediastinoscopic surgery mainly include bleeding, nerve injury and pneumothorax, etc. The incidence rate is less than 2.5%. In recent years, with the continuous development of modern science and technology and medical equipment, the emergence of TV mediastinoscopy has greatly improved the clarity of the mediastinoscopic field and increased the safety and accuracy of the operation. At present, TV mediastinoscopy has become a routine method for the diagnosis of difficult mediastinal diseases and the staging of lung cancer in developed countries such as Europe and America. In the past 4 years, due to various reasons, Chinese thoracic surgeons lacked sufficient knowledge about mediastinoscopic surgery, and due to the limitation of technology and equipment, this technology has not been well developed in China, and only a few hospitals have carried out limited mediastinoscopic surgery, which lags far behind developed countries such as the United States and Europe in terms of the number of cases, types of surgery and popularity. As the only specialized hospital for thoracic diseases in the province, the Department of Thoracic Surgery of Nanjing Chest Hospital has rich experience in the treatment of thoracic diseases. We took the lead in introducing TV mediastinoscopy in the province, accumulated rich experience in TV mediastinoscopy surgery, and successively carried out operations such as parasternal mediastinoscopy and single operation hole through intercostal space to treat pleural effusion in the province.