A transesophageal echocardiogram, or TEE (TOE in the United Kingdom and other countries such as Australia and New Zealand, reflecting the British English spelling transoesophageal), is an alternative way to perform an echocardiogram. A specialized probe containing an ultrasound transducer at its tip is passed into the patient's esophagus. This allows image and Doppler evaluation which can be recorded. It is commonly used during cardiac surgery and is an excellent modality for assessing the aorta, although there are some limitations. It has several advantages and some disadvantages compared with a transthoracic echocardiogram (TTE). Details TEE is a semi-invasive procedure in that the probe must enter the body but does not require surgical (i.e., invasive) cutting for this procedure. Before inserting the probe, mild to moderate sedation is induced in the patient to ease the discomfort and to decrease the gag reflex. Usually a local anesthetic spray (e.g., lidocaine, benzocaine, xylocaine) is used for the back of the throat or as a jelly/lubricant anesthetic for the esophagus. Sedation and anesthesia are required to make the procedure tolerable and safer, as biting the probe, coughing, vomiting, and patient movement would drastically reduce the value of the procedure. Mild or moderate sedation can be induced with medications such as midazolam (a benzodiazepine with sedating, amnesiac qualities), fentanyl (an opioid), or propofol (a sedative/general anesthetic, depending on dosage). Children are anesthetized. Adults are sometimes anesthetized as well if moderate sedation is unsuccessful. Due to the procedure being invasive, sonographers do not perform this procedure unlike transthoracic echo. Once adequate sedation and anesthesia are achieved, the probe is passed through the mouth and into the esophagus. From here, the protocol used for the procedure is highly variable. As the study could be terminated any second (e.g., respiratory compromise, hypotension, intolerance to the probe) the structures of particular interest could be visualized first. For example, if the TEE is ordered to look for mitral regurgitation then the mitral valve may be fully inspected first. At the completion of the study, the probe is removed and patient is monitored for recovery from sedation. Advantages The advantage of TEE over TTE is usually clearer images, especially of structures that are difficult to view transthoracically (through the chest wall). This difficulty with TTE is exemplified with obesity and COPD, as both of these can drastically limit both the window available and the quality of the images obtained through those