Layering of contrast material in oral cholecystography

Serial erect roentgenograms of the gallbladder during oral cholecystography were taken in 50 patients before and after a fatty meal. In the presence of good opacification, layering of opaque and nonopaque bile was noted in most cases 2 hours after the fatty meal. The degree of layering was related to the extent of gallbladder contraction produced by the fatty meal and the degree to which the gallbladder refilled by the inflow of nonopaque liver bile. The layering phenomenon thus appears to be a manifestation of a normally functioning gallbladder and occurs when the gallbladder refills with fresh nonopaque bile.