The value of radiology in predicting gallstone type when selecting patients for medical treatment.

Since medical treatment of gallstones is confined to cholesterol-rich stones, the ability of clinical radiographs to predict gallstone type was tested prospectively by comparing the preoperative radiological appearance of gallstones from 57 unselected patients with cholelithiasis coming to cholecystectomy with the subsequent analysis of the stones both by X-ray diffraction and by chemical techniques. Fifty-two per cent of the patients had 'non-functioning' gallbladders which failed to opacify after at least two contrast examinations and 25 out of 50 had radioopaque stones. Of the 25 patients with radiolucent stones, the stones in 20 ((80%) were predominantly cholesterol in type but radiology was misleading in five; three contained 40-55% calcium salts but were still radiolucent while two were amorphous and contained less than 10% cholesterol by weight on chemical analysis. While radiology was sometimes misleading when the stones were small and irregular, large radiolucent stones with a smooth profile were invariably cholesterol-rich stones. The results also show that in men calcified stones were commoner than in women and that in older women the gallstones contained more calcium salts and less cholesterol than in younger women less than 50 yr). This paper analyses critically the value and limitations of clinical radiology in predicting gallstone type.