An improvement on the standard (transabdominal) ultrasound.

During standard ultrasound the probe is placed externally on the abdomen which limits the resolution of the images. Standard CT images are often not optimal for diagnosing subtle abnormalities in the pancreas and other organs. EUS is an improvement of this technique.

For an EUS, the ultrasound probe is placed in close proximity to the pancreas 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.

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• EUS enables the investigator to identify abnormalities 1 cm or larger. There are small pancreas 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 pancreas 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 is limited by its relatively low accuracy rate (70%) for differentiating between PC and localized pancreatitis. 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.

• In one comparative study of diagnostic methods, the sensitivities for tumors smaller than 3 cm, were 93% EUS, 67% MRI and 53% CT. This study did not include spiral CT, also called helical, which is more accurate than conventional CT. (citation)

• 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.

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