Ultrasound in resuscitation is a necessary tool for evaluating the emergent and unstable patient presenting to the ED. When compared to plain radiography in the diagnosis of free fluid in the thoracic, cardiac, or abdominal cavities, ultrasound is more accurate and time efficient. Severe hypoxia, hypotension, dyspnea, chest pain, ECG abnormalities, tachyarrhythmias, and high-risk conditions such as malignancy and renal failure are a few of the indications to image cardiothoracic structures and their functioning. Cardiac sonography is considered the gold standard of cardiac diagnostic and functional testing. Transesophageal echocardiography (TEE) holds the advantage over transthoracic echocardiography (TTE) of being able to look at the major pulmonary arteries. Unlike other diagnostic imaging modalities, ultrasound is limited by the operator's ability to perform bedside ultrasound. Ultrasound does not allow the physician to distinguish fluid type such as blood and urine, or to evaluate the retroperitoneum.