The etiology of "white bile" in the biliary tree.

"White bile" is the colorless fluid occasionally found in occluded biliary systems. The absence of pigments in this "bile" was not satisfactorily explained. The objectives of this study were to assess its etiology. In dogs, "white bile" developed whenever both the common bile duct and the cystic duct were ligated. In comparison, dark green ("black") bile occurred when only the common bile duct was ligated leaving the gallbladder in communication with the obstructed ducts. The pressure in extrahepatic ducts containing "white bile" was significantly higher than in those filled with "black bile." Flow in the extrahepatic ducts was assessed by the aid of radioiodinated human serum albumin (RIHSA). When "black bile" was present, the direction of flow was from the extrahepatic ducts into the gallbladder. Whenever "white bile" developed, a reverse flow from the extrahepatic ducts into the liver was observed. Thus, the role of the gallbladder appears to be decompression of the biliary system allowing bile flow from the liver even in obstruction. In the absence of the gallbladder water absorption activity, the colorless secretion of the bile ducts seems to "back wash" into the liver and replace the bile present in the ducts at the time of occlusion.