Abdominal Ultrasound FAQ

Fasting for at least 6-8 hours before an abdominal ultrasound is required because eating and drinking introduce air into the stomach and bowel. Sound waves cannot penetrate air, which makes it more difficult to get a clear image of the organs in this area. Eating also causes the gallbladder to contract.

Ultrasound scanning is noninvasive (no needles or injections) and is usually painless. It can give a clear picture of soft tissues that do not show up well on x-ray images.

Ultrasound is less expensive than other imaging methods, causes no health problems and may be repeated as often as is necessary if medically indicated.

Ultrasound waves are reflected by air or gas; therefore ultrasound is not an ideal imaging technique for evaluation of the stomach, small intestine and large intestine. Intestinal gas may also prevent visualization of deeper structures such as the pancreas and aorta. Patients who are obese are more difficult to image because tissue attenuates (weakens) the sound waves as they pass deeper into the body.