Ultrasound of the hepatobiliary-pancreatic system.

Ultrasound (US) remains an excellent first line investigation of the gallbladder and for indicating diagnoses and defining levels of extrahepatic biliary obstruction and screening for liver metastases. It is extremely useful in assisting interventional procedures and assessing the status of hepatic vessels. As a nonoperative procedure, endoscopic ultrasound (EUS) can accurately locate and locally stage pathology of the pancreas and periampullary region and even provide reliable biopsy evidence in experienced hands. A limitation, of course, is its field-of-view restriction, which prevents identification of distant metastatic disease. This restriction is not present with laparoscopic ultrasound (LUS), which apart from being an operative procedure, has all the other advantages of EUS and in addition can identify nodal, hepatic, and extrahepatic metastatic spread. Greater use of intraoperative biopsy should assist in identifying nodal disease but requires the readily available services of a pathologist. Local disease may be even more definable using the newer technology of intraductal ultrasound (IDUS). Intraoperative ultrasound (IOUS), whether direct or via the laparoscope, is now an indispensable tool for all surgeons who want to perform hepatobiliary-pancreatic surgery at the highest level.