What is a mediastinoscopy?
A mediastinoscopy is a surgical procedure performed to examine the mediastinum. The mediastinum is the space behind the sternum (breastbone) in the middle of the chest that separates the two lungs. It contains lymph nodes, the heart and its great vessels, the trachea, the esophagus, and the thymus gland.
The mediastinum can be visualized by the use of an endoscopic instrument called a mediastinoscope. A mediastinoscope is a lighted, long, thin, flexible tube that can visualize the organs and structures of the mediastinum. It also has the capacity to transmit images onto a TV-like monitor.
The procedure is performed in an operating room under general anesthesia. The surgeon makes a small incision in the neck above the top of the sternum and inserts the mediastinoscope. In addition to directly visualizing the mediastinum, tissue samples of mediastinal lymph nodes may be obtained. These lymph nodes receive lymphatic drainage from the lungs. A biopsy of these lymph nodes helps to identify disease processes that may be present in the mediastinum and the lungs.
The primary reason for mediastinoscopy is to visualize, examine, and biopsy lymph nodes for identification of disease processes in the mediastinum, particularly the staging of lung cancer. Determining the “stage” or the extent to which cancer has spread is important in planning the proper treatment. While positron emission tomography (PET scan) is becoming more useful in staging cancer, mediastinoscopy remains an important diagnostic tool when tissue biopsy is required.
Other related procedures that may be used to diagnose problems of the lungs and respiratory tract are chest X-ray, chest fluoroscopy, bronchoscopy, bronchography, chest ultrasound, lung scan, pleural biopsy, oximetry, pulmonary angiogram, pulmonary function tests, sinus X-ray, thoracentesis, computed tomography (CT scan) of the chest, and PET scan. Please see these procedures for additional information.
Anatomy of the respiratory system
The respiratory system is made up of the organs involved in the interchanges of gases, and consists of the:
The upper respiratory tract includes the:
Ethmoidal air cells
The lower respiratory tract includes the lungs, bronchi, and alveoli.
What are the functions of the lungs?
The lungs take in oxygen, which cells need to live and carry out their normal functions. The lungs also get rid of carbon dioxide, a waste product of the body's cells.
The lungs are a pair of cone-shaped organs made up of spongy, pinkish-gray tissue. They take up most of the space in the chest, or the thorax (the part of the body between the base of the neck and diaphragm).
The lungs are enveloped in a membrane called the pleura.
The lungs are separated from each other by the mediastinum, an area that contains the following:
The heart and its large vessels
The right lung has three sections, called lobes. The left lung has two lobes. When you breathe, the air enters the body through the nose or the mouth. It then travels down the throat through the larynx (voice box) and trachea (windpipe) and goes into the lungs through tubes called main-stem bronchi.
One main-stem bronchus leads to the right lung and one to the left lung. In the lungs, the main-stem bronchi divide into smaller bronchi and then into even smaller tubes called bronchioles. Bronchioles end in tiny air sacs called alveoli.
Reasons for the Procedure
A mediastinoscopy is primarily performed to visualize, examine, and biopsy lymph nodes to aid in determining the stage of lung cancer and potential surgical options. Conditions of the mediastinum that may be detected by mediastinoscopy may include, but are not limited to, the following:
Cancer of the lungs, bronchi, and/or or structures in the mediastinum
Infection or inflammation
Lymphoma - a type of cancer in the lymphatic system; includes Hodgkin disease
Sarcoidosis - a condition that causes small, fleshy, swellings in the tissue around organs, usually in the liver, lungs, and spleen
Thymoma - a tumor of the thymus gland (located behind the breastbone, the thymus is part of the immune system)