Diagnosis of Pneumomediastinum
A doctor will take a medical history and perform a physical examination to diagnose pneumomediastinum. They will probably listen to the chest with a stethoscope.

Imaging tests are usually required to see the lungs, airways, and mediastinum. They may include:

Chest X-ray: This test takes pictures of the chest and upper abdominal organs to look for the underlying cause of the air leakage.

CT scan: A CT scan takes a detailed image of the chest so a doctor can check for air in the mediastinum. The scan can show the extent of the pneumomediastinum or confirm cases when a chest X-ray is inconclusive.

Ultrasound: This test uses sound waves to look for air outside the lungs. It can provide instant results and does not use X-rays. A medical gel is placed on the skin so that the ultrasound wand can visualize structures inside the chest cavity.

Other less commonly used tests may be done to identify or confirm an underlying medical condition. These include:

Bronchoscopy: This procedure examines the airways of the lungs, using a thin tube fitted with a light and camera. The tube is inserted through the nose or mouth until it enters the bronchi and small airways of the lungs.

Endoscopy: During this procedure, a tube is passed down the throat or nose into the esophagus, stomach, or upper intestine.

Esophagogram: This test involves someone drinking material that contains barium to coat their esophagus. An X-ray is taken to see the outline of the esophagus and upper digestive tract.