Abdominal Ultrasound

Abdominal ultrasonography.

• To make an initial assessment of abnormalities in the gallbladder, bile ducts, liver, pancreas, spleen, digestive tract, and abdominal cavity. These abnormalities may include gallstones, cysts, tumors, abscesses, inflammation, enlargement, or changes in body tissues.
• To diagnose the presence of fluid in the abdomen, known as ascites.

• For ultrasound of the liver, gallbladder, pancreas, or digestive tract, you will be asked to fast overnight or for at least six hours prior to the test, which reduces bowel gas that can obscure the image and keeps the gallbladder filled with bile, making it easier to visualize its contents.
• For ultrasound of the stomach, duodenum, or small bowel, you may be given water to drink immediately before the test because these organs are better visualized if they are filled with fluids. A water enema may be used to fill the colon with fluids.
• You remove your clothing before the test and don a hospital gown.

In a new approach known as endoscopic ultrasound, ultrasound is combined with endoscopy. In this case, a miniature ultrasound probe attached to a viewing tube called an endoscope is inserted into the digestive tract (see the description of esophagogastroduodenoscopy below). The method makes it possible to sweep the ultrasound probe over the organ that needs to be examined with minimal interference of other tissues or gas. It is particularly valuable in detecting abnormalities in organs such as the pancreas, which are difficult to examine with regular ultrasound because they are largely covered by the bowel.

The abdominal ultrasonogram is assessed for the size, shape, and composition of different structures. In cirrhosis of the liver, ultrasound may detect changes in the way blood passes through the large vessels entering or leaving the liver. In people with jaundice, it can determine whether the disorder is caused by a blocked bile duct or by disease of the liver cells. Gallstones produce characteristic shadows on a sonogram and can be detected in the gallbladder with near-perfect accuracy.

• If liver or pancreatic disease is suspected, a CT scan may identify abnormalities not seen by ultrasound.
• If disease of common duct of gallbladder is suspected, ERCP may be necessary.