It is a non-invasive diagnostic examination that helps visualize the organs and structures within the chest, such as the lungs, mediastinum (area that contains the heart, thymus, aorta, trachea, esophagus, and lymph nodes), and pleural space (a fluid-filled space). Ultrasound is also helpful in assessing blood flow to chest organs. Your doctor may advise this test to find out the presence of excess fluid in the chest. A chest ultrasound can also be used to see how well your diaphragm moves, look at the heart and its valves, and see areas that are denser than others.