Ultrasound is an imaging modality which allows non-invasive visualization of internal organs such as the heart, liver, and kidney. The probe of the ultrasound unit emits ‘echos’ or ultrasound waves which are variably passed through various tissue densities and translated into an image. Most people are familiar with ultrasound images due to maternity ultrasound imaging when families are growing.
Fluid such as blood or urine shows up black in the ultrasound image, and organs of various density are more less gray/white relative to fluid depending on their structure. There are characteristic patterns for certain organs, such as the ‘bean shape’ of the kidney. Air/gas, such as in the lungs, cannot transmit the ultrasound waves and therefore the lungs cannot be imaged unless they collapsed.
The ultrasound can be used to image organs for suspected or known structural abnormalities, as well as visualizing masses and effusions. Urinary stones, gall bladder stones, free blood, nodules, and cancerous tumors can be seen. Given the patient has normal clotting function, fine needle aspirates can be performed. The heart can also be imaged, with a view of valvular structures and tracking of blood flow.
Benefits of ultrasound are non- invasive nature vs surgery or endoscopy. It is superior to radiography in terms of evaluating cardiac function, but most often be used in conjunction with other tests such as ECG.