Ultrasound is a painless and noninvasive diagnostic imaging method that does not expose the patient to radiation. It employs high-frequency sound waves to help doctors visualize the internal organs and, in cases of pregnancy, the unborn fetus on a computer monitor. Having an ultrasound requires the patient to lie on a table while a radiology technician or their physician glides a hand-held “transducer” over the area that is being examined. Also known as sonography, this form of testing can assist in the diagnosis of such conditions as gallbladder disease, certain cancers, thyroid problems, and abnormalities affecting the prostate and genitals. It can also help in evaluating the blood vessels, and is frequently employed to guide other medical procedures such as a fine needle biopsy. While most ultrasound tests are conducted using a transducer that remains outside the body, several types are conducted internally. These include transrectal and transvaginal ultrasounds as well as transesophageal echocardiograms. Depending on which procedure you receive and what condition is being evaluated, most ultrasounds require less than an hour to complete.