Occasionally the images from a standard transthoracic echocardiogram do not provide the level of detail that is needed for some heart conditions, and it is recommended to have a trans-oesophageal echocardiogram. This is very similar to an endoscopy. The ultrasound transducer is mounted on a thin tube that is passed through the mouth to the oesophagus. This means it sits very close to the heart and extremely clear images are obtained. It is necessary to have sedation for this, and the mouth and gullet will be anaesthetised beforehand with a spray.