[Radiologic and ultrasound detection of gallstones]

Ultrasonography (US) is the method of choice for evaluation of gallbladder stones with an accuracy of 96%. Number, size and calcification can be assessed by virtue of US reflection and attenuation. If more than five stones are present, the accuracy decreases. To determine the calcium content of stones more precisely, computed tomography can be used. This allows an assessment of the success rate of lithotripsy and chemolysis. Oral cholecystography is an alternative method of similar accuracy as US. It provides additional information about the patency of the cystic duct. In the presence of ductal stones, the accuracy of US decreases to 30%, mainly because of overlying bowel gas. Since 8 to 16% of all cases of cholecystolithiasis are accompanied by choledocholithiasis and since this entails a change in treatment, intravenous cholecystocholangiography with an accuracy of more than 90% is the method of choice in this case. Additionally, it provides knowledge on the biliary anatomy preoperatively. It does not, however, replace US, because opacification of the gallbladder is limited with this method. If intravenous cholecystocholangiography fails in case of impaired liver function, transcholecystic cholangiography or, in cases of dilated ducts, percutaneous transhepatic cholangiography can be used. Plain film radiography is not a suitable technique, since only 10 to 15% of all gallstones calcify.