The only sensation the patient experiences is the transducer, which sends and receives sound, being moved over the skin. Ultrasound is not good at looking at or through bones, so fractures are best diagnosed with X-rays. Ultrasound does not travel through air, so it is not useful in situations where much gas is present or in examining the lungs. In order to look at the pelvic organs, the bladder must be full. This allows the sound to be transmitted better and also pushes gas in the intestines out of the way to give the radiologist clearer pictures of the uterus and ovaries.
Food can cause the gallbladder to empty, so it can t be examined for gallstones.
Also, most people swallow air when they eat and air prevents ultrasound from being transmitted. No one has ever shown ultrasound to cause problems. Your radiologist and radiology technologist have the training to use the least amount of ultrasound possible to get the information they need. They also use the most expensive and highest quality equipment available to do your examination. Though your technologist is trained to perform the exam, only your radiologist can tell for sure what the pictures mean.