Endoscopic Ultrasound

An improvement on the standard (transabdominal) ultrasound.

Ultrasonography of the liver and gallbladder is usually the first radiologic study used to evaluate jaundice or right-upper quadrant (abdominal) pain. During standard ultrasound the probe is placed externally on the abdomen which limits the resolution of the images. Ultrasound often detects large gallbladder cancers, but often misses smaller extrahepatic bile duct cancer. Standard CT images are often not optimal for diagnosing subtle abnormalities in the bile ducts and other organs. EUS is an improvement of this technique.

Procedure:

For an EUS, the ultrasound probe is placed in close proximity to the bile ducts by attaching it to the end of a standard gastrointestinal endoscope and passing the scope in the mouth, down the esophagus and into the stomach and duodenum . This produces a much clearer image than a transabdominal ultrasound.

Accuracy:

• EUS enables the investigator to identify abnormalities 1 cm or larger. There are small bile duct cancers that can be detected with EUS that cannot be visualized currently with a CT scan. Technological improvements are enabling a generation of more accurate images of the bile ducts and such improvements are expected to continue.

• It is the most accurate method for detecting the spread of cancer to the portal vein (not as accurate for arterial involvement).

• EUS will visualize masses of less than 1 cm but often will not be able to determine whether the mass is a cancerous. Fine needle aspiration done in conjunction with EUS may overcome this limitation.

• The main variable in the success of an EUS investigation is the experience of the endoscopist. The technique is difficult and the optimal use of this technique depends on the considerable skill of the endoscopist. Many centers now have endoscopists trained in the technique, but EUS is still not available at all medical centers.

Risks :

When done in conjunction with FNA there is a low risk of complication, 5 out of 124 patients 1.1%), all non-fatal complications. Fever, inflammation, perforation of duodenal or esophageal wall, hemorrhage of cystic tumor.