General Information:

• Description: A transmitter is pressed gently against the abdominal wall. Sound waves are emitted from the transmitter and then bounce off of the internal organs. Information can be obtained about the internal organs by studying the appearance of the sound waves as they bounce off of the organs. A radiology technician or doctor at an office or x-ray facility performs the test. A doctor interprets the results. The test takes 30-60 minutes to complete.
• Results: Usually within 2 days, within 1 hour in emergency situations. 
• Variations: Endoscopic ultrasound combines endoscopy and ultrasound. A small ultrasound probe attached to an endoscope (see the description of esophagogastroduodenoscopy) is inserted into the digestive tract via the mouth. This makes it possible to examine organs with minimal interference of other tissues or gas. This method is helpful at identifying abnormalities in the esophagus, stomach, bile duct and pancreas.
• Other Names: Sono or sonography

Indications for the Test:

• Examine the organs of the abdomen
• Sono can examine the liver, bile ducts, gallbladder, pancreas, spleen, appendix, and female organs
• Ascites (collection of fluid in the abdomen) can be detected

Preparation:

• You might be asked to fast overnight or for at least six hours prior to the test
• You might be asked to wear a hospital gown 

Procedure: 

• While lying flat, a clear jelly is applied to the abdomen. Then the probe is rubbed over the abdominal wall. A computer in the ultrasound machine produces the images.

After the Test:

• You may dress and leave.

Factors Affecting Results:

• Several factors may affect the images: movement, obesity, and the presence of gas in the bowel that may overlie the organ of interest.

Advantages:

• The test is quick and painless. 
• The test is noninvasive. 
• The test is particularly good at evaluating the solid organs of the abdomen. 
• The test is easier and less expensive than a CT. 

Disadvantages: 

• The cause of an abnormality may not be apparent from the test. 
• Bowel gas can interfere with obtaining good images. 
• The test is generally less effective at locating small abnormalities in the abdomen. 
• The test is not good at examining the intestines.