A transesophageal echocardiogram (TEE) is a test that uses sound waves to produce images of the heart in the exact same way that a transthoracic or "regular" echocardiogram does. However, with a transesophageal echocardiogram the probe is passed through the patients mouth into the esophagus (tube that carries food to the stomach) into position behind the heart. From this position excellent images of the heart can be obtained in patients that may not have adequate images from a transthoracic echocardiogram.
During the test patients are generally sedated by another physician and sleep through the procedure. These test are done routinely on patients in the operating room during surgical procedures and often during interventional procedures in the catheterization laboratory. They are also done as outpatients in teenagers and adults when needed if transthoracic imaging is not adequate.