Mediastinoscopy is a type of ‘keyhole’ surgery where only very small cuts (incisions) are made to the body allowing doctors doctors to view the middle of the chest cavity. The mediastinoscope, a thin, tube-like instrument which has a camera built into the end, is inserted into a small incision in the upper chest. This is then linked up to a monitor allowing the surgeon to see pictures of the chest. It allows the surgeon to remove lymph nodes from between the lungs and to test them for cancer or infection. It is also useful for examining the outside surface of the large tubes of the airways or for evaluating tumors or masses in the middle chest.