Ultrasound

Ultrasound uses reflected sound waves to produce a picture of structures within the body. It does not use X-rays or other types of possibly harmful radiation.

A small handheld instrument known as a transducer is passed back and forth over the area being examined. It sends out high-pitched sound waves (inaudible to humans) that are reflected back to the transducer. A computer analyzes the sound waves to create a picture displayed on the monitor called a sonogram, echogram or scan.

Purpose
An ultrasound is done to:

• Detect, measure or monitor problems within the body related to disease or injury, including such conditions as gallstones, enlarged spleen, pancreatitis and jaundice. It can also help to determine the cause of blocked flow in a kidney or investigate recurring urinary tract infections. It can be useful as a diagnostic tool for virtually any part of the body, including the head.

How to prepare
If you are having an abdominal MRI:

• Tell your doctor if you have had a barium enema or a series of upper GI (gastrointestinal) tests within the past 2 days. Barium that remains in the intestines can interfere with the ultrasound test.

Other preparations depend on the reason for the abdominal ultrasound test you are having.

• For ultrasound of the liver, gallbladder, spleen, and pancreas, you may be asked to eat a fat-free meal on the evening before the test and then to avoid eating for 8 to 12 hours before the test.
• For ultrasound of the kidneys, you may not need any special preparation. You may be asked to drink 4 to 6 glasses of liquid (usually juice or water) about an hour before the test to fill your bladder. You may be asked to fast for 8 to 12 hours before the test if the liver, gallbladder, spleen, and pancreas are to be evaluated also.
• For ultrasound of the aorta, you may need to avoid eating for 8 to 12 hours before the test.

How It Is Done
This test is done by a doctor who specializes in performing and understanding imaging tests (radiologist) or by an ultrasound technologist.

You will need to remove any jewelry that might interfere with the ultrasound scan. You will need to take off all or most of your clothes, depending on which area is examined (you may be allowed to keep on your underwear if it does not interfere with the test). You will be given a cloth or paper covering to use during the test.

You will lie on your back (or on your side) on a padded exam table. Gel will be spread on your abdomen to improve the quality of the sound waves. The transducer is pressed against your abdomen and moved back and forth over it. A picture of the organs and blood vessels can be seen on a video monitor.

You may be asked to change positions so additional scans can be made. For a kidney ultrasound, you may be asked to lie on your stomach.

You need to lie very still while the ultrasound scan is being done. You may be asked to take a breath and hold it for several seconds during the scanning.

Abdominal ultrasound takes about 30 minutes. You may be asked to wait until the radiologist has reviewed the information. The radiologist may want to do additional ultrasound views of some areas of your abdomen.

How it Feels
You will feel light pressure from the transducer as it passes over your abdomen, but you should feel no discomfort. However, if the test is being done to assess damage from a recent injury, the slight pressure of the transducer may be somewhat painful. You will not hear the sound waves.

Risks
There are no known risks from having an abdominal ultrasound test.