An Ultrasound Examination, also known as Ultrasonography or Echosonography, is an imaging technique that allows internal body structures to be seen by recording echoes of ultrasonic waves. Unlike x-rays, which can be potentially dangerous, ultrasound waves are considered to be entirely safe. Ultrasound equipment directs a narrow beam of high frequency sound waves into an area of interest. The sound waves may be transmitted through, reflected or absorbed by the tissue toward which they are pointed. As the beam strikes the interface or boundary between two tissues, some of the ultrasound waves are absorbed and others are reflected back. These reflected sound waves are converted into electrical impulses that are displayed on a monitor. This gives a 2-dimensional “picture” of the tissues under examination.
The technique is invaluable for the examination of internal organs and was first used in veterinary medicine for pregnancy diagnosis. However, the technique is also extremely useful in evaluating heart conditions and identifying changes in abdominal organs. Ultrasonography is very useful in the diagnosis of cysts and cancers. Ultrasound guided cystocentesis is also a helpful tool for urine collection, which allows precise placement of the needle into the bladder. Ultrasound examinations are of little value in examining organs that contain air. Ultrasound waves will not pass through air and therefore it cannot be used to examine the lungs.
Anesthesia is not usually needed for most ultrasound examinations. This is one of the great advantages of ultrasound. The technique is non-invasive but does involve clipping an area of hair and applying a water-soluble jelly on the skin. The technique is totally painless and most pets will lie comfortably while the scan is being performed. Occasionally, if the pet is very frightened or fractious, a sedative may be necessary.